Assay apparatuses, methods and reagents

ASSAY APPARATUSES, METHODS AND REAGENTS 192157/2

ASSAY APPARATUSES, METHODS AND REAGENTS

FIELD OF THE INVENTION

The invention relates to apparatuses, systems, methods, reagents, and kits for conductingassays. Certain embodiments of the apparatuses, systems, methods, reagents, and kits of theinvention may be used for conducting automated sampling, sample preparation, and/or sampleanalysis in a multi-well plate assay format. For example, they may be used for automated analysis ofparticulates in air and/or liquid samples derived therefrom. WO 2008/057111 PCT/US2006/049049 2

BACKGROUND OF THE INVENTION

Numerous methods and systems have been developed for conducting chemical,biochemical, and/or biological assays. These methods and systems are essential in avariety of applications including medical diagnostics, food and beverage testing, 5 environmental monitoring, manufacturing quality control, drug discovery, and basic scientific research.

Multi-well assay plates (also known as microtiter plates or microplates) havebecome a standard format for processing and analysis of multiple samples. Multi-wellassay plates can take a variety of forms, sizes, and shapes. For convenience, some 10 standards have appeared for instrumentation used to process samples for high- throughput assays. Multi-well assay plates typically are made in standard sizes andshapes, and have standard arrangements of wells. Arrangements of wells include thosefound in 96-well plates (12x8 array of wells), 384-well plates (24 xl6 array of wells),and 1536-well plates (48 x 32 array of wells). The Society for Biomolecular Screening 15 has published recommended microplate specifications for a variety of plate formats(see http://www.sbsonline.org). A variety of plate readers are available for conducting assay measurements inmulti-well plates including readers that measure changes in optical absorbance,emission of luminescence (e.g., fluorescence, phosphorescence, chemiluminescence, 20 and electrochemiluminescence), emission of radiation, changes in light scattering, andchanges in a magnetic field. U.S. Patent Application Publications 2004/0022677 and2005/0052646 of U.S. Patent Applications 10/185,274 and 10/185,363, respectively, ofWohlstadter et al. describe solutions that are useful for carrying out singleplex andmultiplex ECL assays in a multi-well plate fonnat. They include plates that comprise a WO 2008/057111 PCT/US2006/049049 3 plate top with through-holes that form the walls of the wells and a plate bottom that issealed against the plate top to form the bottom of the wells. The plate bottom haspatterned conductive layers that provide the wells with electrode surfaces that act asboth solid phase supports for binding reactions as well as electrodes for inducing 5 electrochemiluminescence (ECL). The conductive layers may also include electricalcontacts for applying electrical energy to the electrode surfaces.

Despite such known methods and systems for conducting assays, improvedapparatuses, systems, methods, reagents, and kits for conducting automated sampling,sample preparation, and/or sample analysis in a multi-well plate assay format are 10 needed.

SUMMARY OF THE INVENTION

We describe apparatuses for conducting assays in a multi-well plate format thathave one or more of the following desirable attributes: i) high sensitivity, ii) large 15 dynamic range, iii) small size and weight, iv) array-based multiplexing capability, v)automated operation (including sample and/or reagent delivery); vi) ability to handlemultiple plates, and vii) ability to handle sealed plates. We also describe componentsthat are useful in such an apparatus, and methods for using such an apparatus andcomponents. They are particularly well suited for, although not limited to, use for 20 autonomous analysis of environmental, clinical, or food samples. The apparatus andmethods may be used with a variety of assay detection techniques including, but notlimited to, techniques measuring one or more detectable signals. Some of them aresuitable for electrochemiluminescence measurements and, in particular, embodimentsthat are suitable for use with multi-well plates with integrated electrodes (and assay 192157/2 methods using these plates) such as those described in U.S. Publications 2004/0022677 and 2005/0052646 of U.S. Applications 10/185,274 and 10/185,363, respectively, of

Wohlstadter et al., and US Patent No. 7,807,448 of Glezer et al. entitled "Assay Modules

Having Assay Reagents and Methods of Making and Using Same” 5 An apparatus is provided for measuring a signal from wells of sealed multi-well assay plates comprising a) a seal removal tool for removing seals from wells of the multi-well plates, and b) a detection system for measuring the signal from wells of said multi-well plate.

The seal removal tool may function by i) piercing sealing films with a 10 probe with a seal piercing tip, ii) grabbing and removing caps on wells, iii) peeling sealing films from the tops of wells, or iv) removing the seal with a coring tool.

In one embodiment, the seal removal tool is a piercing probe that comprises i) a piercing section with external surfaces that taper to a vertex so as to form a piercing tip at one end of a piercing direction (the axis of translation during a piercing operation) 15 and ii) a seal displacement section, arranged adjacent to the piercing section along the piercing direction. In certain specific embodiments, the seal displacement section has a cross-sectional shape, perpendicular to the piercing direction, that is selected to substantially conform to the shape of the openings of the wells on which the probe willoperate. The probe may be slightly undersized relative to the well opening so as to 20 allow the probe to slide into the well opening, and press or fold the pierced seal againstthe well walls. Such an approach may be used to remove the seal as a barrier to detectingassay signals in the well using detectors (for example, light detectors and/or light imaging systems) situated above the well. The appropriate clearance may be WO 2008/057111 PCT/US2006/049049 5 selected based on the thickness of a specific film and/or may be selected to be less thanabout 0.1 inches, less than about 0.2 inches, or less than about 0.3 inches.

In one example of a piercing tool, the cross-sectional shape of the sealdisplacement section is a circle. In another example, it is a square or a square with 5 rounded comers. The piercing section may be conical in shape. Alternatively, it mayinclude exposed cutting edges that, e.g., extend in a radial direction from the tip andcan act to cut the seal during piercing and aid in reproducibly folding the seal againstthe well walls. In one specific example, the tip is pyramidal in shape, the edges of thepyramid providing exposed cutting edges. 10 In certain embodiments, the piercing probe is spring loaded such that the maximal downward force, along said piercing direction, of the probe on a plate seal isdefined by the spring constant of a spring. The probe may also comprise a plate stopsection adjacent to said seal displacement section that defines the maximum distance oftravel of said piercing probe into said wells. In one specific example, the stop section is 15 a region of the probe with a width that is too large to enter a well and the maximumdistance is defined by the distance at which the stop section hits the top of the well.

The apparatus may further comprise a pipetting probe. In one embodiment, thepiercing probe has a through-hole parallel to the piercing direction. The through-holeis, optionally, off-set from the piercing tip, and the pipetting probe is movably located 20 in the through-hole such that it can be withdrawn into the piercing probe when thepiercing probe is being used to remove a well seal and it can be extended from thepiercing probe during pipetting operations. The piercing probe and pipetting probemay be controlled independently, e.g., by separate motors. Alternatively, one motormay be used to drive both probes. In one example, the piercing probe comprises a plate WO 2008/057111 PCT/US2006/049049 6 stop section as described above and the pipetting probe is coupled to the piercing probeby a spring. The spring is selected to have a spring constant such that i) when theprobes are not exerting force on an object, the pipetting probe is withdrawn into thethrough-hole in the piercing probe, ii) translation of the pipetting probe toward a well 5 results in the co-translation of the piercing.probe and allows for the delivery ofsufficient force to displace a seal on the well, and iii) continued translation past themaximal distance of travel of the piercing probe results in compression of the springand extension of the pipetting probe from the piercing probe into said well where itmay be used to pipette liquids into and out of the well. 10 A method is provided of using the apparatuses comprising seal removal tools (described above), the method comprising removing a seal from a well of a multi-wellplate and detecting said signal from said well. Removing a seal may include piercingthe seal on a well of a multi-well plate and, optionally, cutting the seal into sections(e.g., with using cutting edges on a piercing tip) and folding the sections against the 15 internal walls of the well. The method may further include one or more of: pipetting asample into the well, pipetting an assay reagent into the well, removing a liquid fromthe well, washing the well, illuminating the well, or applying an electrical potential toelectrodes in the well. Additionally, the method may further comprise repeating someportion or all of the process described above on one or more additional wells of the 20 plate. A reagent cartridge is provided which may be used to deliver reagent used byand store waste generated by a multi-well plate analysis apparatuses. According to oneembodiment, a reagent cartridge comprises a cartridge body that encloses an internalvolume. The cartridge body has a reagent port and a waste port for delivering reagent WO 2008/057111 PCT/US2O06/049O49 7 and receiving waste. The reagent cartridge also comprises reagent and wastecompartments in the cartridge body that are connected, respectively, to the reagent andwaste ports. The volume of the compartments are adjustable such that the relativeproportion of the volume of the cartridge body occupied by reagent and waste can be 5 adjusted, e.g., as reagent is consumed in assays and returned to the cartridge as waste.The total internal volume of the cartridge body may be less than about 2, less thanabout 1.75, less than about 1.5, or less than about 1.25 times the volume of liquid storedin the body, e.g., the volume of reagent originally provided in the cartridge, thusminimizing the space required for waste and reagent storage, and allowing for 10 convenient one-step reagent replenishment and waste removal. In certain embodiments, the apparatus has a reagent cartridge slot configured to receive thecartridge, and provide fluidic connection to the waste and reagent ports, optionally via“push-to-connect” or “quick connect” fittings.

The reagent and waste compartments may be provided by collapsible bags 15 located in the cartridge body. Alternatively, one of the reagent and waste compartments may be provided by a collapsible bag and the other may be provided bythe cartridge body itself (i.e., the volume in the cartridge body excluding the volumedefined by any collapsible bags in the cartridge body). In addition to the first reagentand waste compartments, the reagent cartridge may further comprise one or more 20 additional collapsible reagent and/or waste compartments connected to one or moreadditional reagent and/or waste ports.

Methods of using the reagent cartridges are provided. The method comprisesremoving reagent from the reagent compartment and introducing waste into the wastecompartment. In certain embodiments, at least about 70%, at least about 80%, or at WO 2008/057111 PCT/US2006/049049 8 least about 90% of the reagent volume is reintroduced into the reagent cartridge as waste.

Liquid dispensers are provided. The dispenser may be used to add or removeliquids from the wells of a multi-well plate. An assay apparatus is provided that 5 includes the dispenser. One embodiment of the liquid dispenser comprises a pipettingprobe comprising a vertical tube element. The dispenser also comprises a probe guidethat supports the tube element in a vertical orientation, and configured to allow saidtube element to move vertically in the guide between a fully extended position and afully retracted position. The dispenser further comprises a spring element coupled to 10 the vertical tube element and probe guide that biases the tube element to the fully extended position (i.e., extended downward). A vertical translation stage is attached tothe probe guide to raise and lower the probe.

The tube element has a lower opening through which fluid is dispensed oraspirated. In one embodiment, the lower opening is a blunt tube end. Optionally, the 15 end may be slotted to allow movement of fluid through the opening when the openingis pressed against a flat surface. In certain embodiments, the dispenser comprises twoor more tube elements. In one specific example different reagents are dispensedthrough different tube elements. In another specific example, one tube element is usedto dispense reagent and another tube element is used to aspirate waste. Multiple tube 20 elements may be configured in a variety of arrangements, for example, as parallel tubes or concentric tubes. A method is provided for using the liquid dispenser for adding or withdrawingfluid from a container, e.g., a well of a multi-well plate. One method comprises a)lowering the pipetting probe into the container by lowering the translation stage until WO 2008/057111 PCT/US2006/049049 9 the probe touches a bottom surface of the container, b) continuing to lower thetranslation stage such that said tube element pushes against the spring and retracts intothe probe guide to a position between said fully extended and fully retracted positions,c) adding fluid to and/or withdrawing fluid from the container through the pipetting 5 probe, and d) raising the pipetting probe out of said container by raising said translationstage.

In a specific embodiment employing a container with a piercable seal, themethod may further comprise lowering the translation stage until the probe contacts andpierces the seal. In addition, piercing the seal may further comprise e) lowering the 10 translation stage until the pipetting probe contacts the plate seal, f) continuing to lowerthe translation stage such that the tube element pushes against the spring and retracts inthe probe guide to the fully retracted position, and g) continuing to lower the translationstage such that the pipetting probe pierces the plate seal and the tube element returns tothe fully extended position. 15 An apparatus is provided for conducting luminescence, assays in multi-well plates. One embodiment comprises a light-tight enclosure that provides a light-freeenvironment in which luminescence measurements may be carried out. The enclosureincludes a plate translation stage for translating a plate horizontally in the enclosure tozones where specific assay processing and/or detection steps are carried out. The 20 enclosure also includes an enclosure top having one or more plate introductionapertures through which plates may be lowered onto or removed from the platetranslation stage (manually or mechanically). A sliding light-tight door is used to sealthe plate introduction apertures from environmental light prior to carrying out luminescence measurements. WO 2008/057111 PCT/US2006/049049 10

The apparatus may also comprise a light detector which may be mounted withinthe light-tight enclosure or, alternatively, it may be mounted to a detection aperture onthe enclosure top (e.g., via a light-tight connector or baffle). In certain embodiments,the light detector is an imaging light detector such as a CCD camera and may also 5 include a lens. The apparatus may also comprise pipetting systems, seal piercing systems, reagent and waste storage containers, tube holders for sample or reagent tubes,fluidic stations for delivering/removing samples/ reagents/waste, etc. Thesecomponents may be conventional components such as components known in the art.Alternatively, the apparatus may employ specific components as described herein. 10 Furthermore, the apparatus may comprise computers or other electronic systems forcontrolling operation the apparatus including, e.g., operating motorized mechanicalsystems, and triggering and/or analyzing luminescence signals.

Another embodiment of an apparatus for conducting luminescence assays inmulti-well plates comprises a light-tight enclosure comprising i) one or more plate 15 elevators having plate lifting platforms that can be raised and lowered, ii) a light-tightenclosure top having one or more plate introduction apertures positioned above theplate elevators and a detection aperture, the enclosure top comprising a sliding light-tight door for sealing the plate introduction apertures, and iii) a plate translation stagefor translating a plate in one or more horizontal directions. The plate translation stage 20 comprises a plate holder for supporting the plate which has an opening under the plate to allow plate elevators positioned below the plate holder to access and lift the plate.

Furthermore, the plate translation stage being configured to position plates below the detection aperture and to position the plates above the plate elevators. WO 2008/057111 PCT/US2006/049049 11

The apparatus further comprises one or more plate stackers and a light detector.The plate stackers are mounted on the enclosure top above the plate introductionapertures and are configured to receive plates from or deliver plates to the plateelevators. The light detector is mounted on the enclosure top and coupled to the 5 imaging aperture with a light-tight seal.

Certain specific embodiments of the apparatus may further comprise a pipettingsystem for delivering liquids to or removing liquids from the wells of an assay plate inthe apparatus. In one specific embodiment, the pipetting system comprises a pipettingprobe mounted on a pipette translation stage for translating said pipetting probe in a 10 vertical direction and, optionally, in one or more horizontal directions. Furthermore,the enclosure top has one or more pipetting apertures and the sliding light-tight doorhas one or more pipetting apertures. The sliding light-tight door has a pipettingposition where the pipetting apertures in the enclosure top align with the pipettingapertures in the sliding light-tight door. The pipette translation stage is mounted on the 15 enclosure top and configured such that, when the sliding light-tight door is in the pipetting position, the pipetting probe may be lowered to access wells positioned underthe pipetting apertures in the enclosure top.

Another optional component of the apparatus is a seal removal tool such as aplate seal piercing probe. In one example, the enclosure top and sliding light-tight door 20 have piercing probe apertures and the light-tight door has a piercing position where thepiercing apertures in the door and top align. The piercing probe is mounted on theenclosure top and configured such that, when the sliding light-tight door is in thepiercing position, the piercing probe may be lowered so as to pierce seals on wellspositioned under the piercing apertures in the enclosure top. Advantageously, when 192157/2 12 both the piercing probe and the pipette probe are present, both may be driven with asingle translation stage, e.g., as described above for the integrated pipetting/piercingtool. In an alternate embodiment, a pipette translation stage supporting the pipetteprobe comprises a probe translation element and the pipette translation stage is 5 configured to travel horizontally and grab the piercing probe with the probe translationelement, and to travel vertically to lower and raise said piercing probe.

Additional optional components of the apparatus are plate contacts for makingelectrical contact to the plates and providing electrical energy to electrodes in wellspositioned under said light detector (e.g., for inducing ECL). 10 A method is also provided for using the apparatus for conducting luminescence assays in multi-well plates. The plates may he conventional multi-well plates. In certainembodiments, plates adapted for use in electrochemiluminescence assays are employedas described in U.S. PatentNos. 7,842,246; 6,977,722; and 7,858,321. In assaymethods that detect ECL from one well at a time, the electrode and electrode 15 contacts in these wells are adapted to allow application of electrical energy to electrodes in only one well at a time. The apparatus my be particularly well-suited forcarrying out assays in plates containing dry reagents and/or sealed wells, e.g., asdescribed in U.S. Patent No. 7,807,448 of Glezer et al. entitled "Assay ModulesHaving Assay Reagents and Methods of Making and Using Same," 20 In one embodiment, the method comprises: a) introducing a plate to a plate stacker, b) opening the light-tight door, c) lower the plate from the plate stacker to theplate holder on the plate translation stage, d) sealing the light-tight door, e) translatingthe plate to position one or more wells under the light detector, e) detectingluminescence from the one or more wells, f) opening the light-tight door, g) translating WO 2008/057111 PCT/US2006/049049 13 the plate to a position under a plate stacker, and h) raising the plate to the plate stacker.The method may further comprising translating said plate carriage to position one ormore additional wells under said light detector and detecting luminescence from saidone or more additional wells. The method may also, optionally, comprise one or more 5 of: i) pipetting sample/or reagent into or out of one of said wells, ii) removing sealsfrom one or more of said wells, or iii) applying electrical energy to electrodes in one ormore of said wells (e.g., to induce electrochemiluminescence).

Where the apparatus comprises a pipetting probe, and the enclosure top andsliding door includes pipetting apertures, the method may further comprise: sliding the 10 sliding light-tight door to the pipetting position and using the pipetting probe tointroduce and/or remove reagent and/or sample from one or more wells of the plate.Where the apparatus comprises a seal piercing probe, and the enclosure top and slidingdoor includes piercing apertures, the method may further comprise: sliding the slidinglight-tight door to the piercing position, aligning a well of the plate under the piercing 15 probe, and piercing a seal on the well. They may be repeated to seal additional wells ofthe plate. In one embodiment, a seal on a well of a plate is pierced with the sealpiercing tool prior to being accessed by a pipetting probe. In another embodiment, thewell is first accessed by a pipetting probe (which pierces the seal to form one or moresmall holes or tears in the seal. The well is then subsequently pierced with the piercing 20 probe to fully displace the seal and allow for unencumbered detection of signal from the well.

The light detector may be a conventional light detector such as a photodiode,avalanche photodiode, photomultiplier tube, or the like. Suitable light detectors alsoinclude arrays of such light detectors. Light detectors that may be used also include WO 2008/057111 PCT/US2006/049049 14 imaging systems such as CCD and CMOS cameras. The light detectors may alsoinclude lens, light guides, etc. for directing, focusing and/or imaging light on thedetectors. In certain specific embodiments, an imaging system is used to imageluminescence from arrays of binding domains in one or more wells of an assay plateand the assay apparatus reports luminescence values for luminescence emitted fromindividual elements of said arrays.

An environmental monitoring system is also provided that comprise an analytedetection module and an air sampling system. The air sampling system processes air toconcentrate particulate matter in the air and suspend the particulates in a liquidsuspension. The detection module is an apparatus for conducting luminescence assaysin multi-well plates as disclosed herein. In operation, the air sampling systemprocesses air for a certain period of time and delivers sample to the analyte detectionmodule, which then carries out assays for one or more target analytes in one or morewells of an assay plate and, on completion of the assay, reports results. The airsampling system, detection module, and interface between the two components,preferably, is designed to operate in an autonomous fashion. At selected intervals oftime, additional samples are delivered from the air sampling system to the detectionmodule and analyzed in unused wells of the assay plate. The assays may be scheduledto be run in a serial fashion. Alternatively, the assays may be scheduled to be run in astaggered fashion in which some steps overlap. Through the use of multi-well plates(and plate stackers that hold multiple multi-well plates) long periods of autonomousoperation can be achieved without requiring replenishment of consumables. WO 2008/057111 PCT/US2006/049049 15

BRIEF DESCRIPTION OF DRAWINGS

Figure 1 shows an assembled view of multi-well plate reader 100.

Figure 2 shows a view of plate reader 100 that exposes embodiments of the light detection and fluidic components. 5 Figure 3 shows one embodiment of a light detection system 160 of plate reader 100.

Figure 4 shows embodiments of certain fluidic and seal piercing components.Figure 5 shows an embodiment of a sample/waste station 300.

Figures 6a-6c show an embodiment of a spring-loaded pipette probe 400. 10 Figures 7a-7b show an embodiment of a plate seal piercing probe 225.

Figure 8 shows an embodiment of an integrated plate seal piercer/pipettor 500.Figures 9a-9c show top views of an embodiment of light-tight enclosure 110 of plate reader 100 and illustrates the operation of sliding light-tight door 150 (shown incross-hatch). 15 Figure 10 shows a view of the mechanical components present in one embodiment of light-tight enclosure 110 of plate reader 100.

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The Detailed Description section provides descriptions of certain embodiments 20 of the invention that should not be considered limiting but are intended to illustratecertain inventive aspects. Figure 1 shows an isometric view of one embodiment ofmulti-well plate reader 100. Plate reader 100 has a light-tight enclosure 110 and afluidic/imaging system enclosure 130. Input and output plate stackers 122 and 120,respectively, hold plates 105 for use in assays (plates are shown as having optional WO 2008/057111 PCT/US2006/049049 16 plate seals). Plate stackers 120 and 122 have plate release latches 125 that are springloaded to allow plates raised from the light-tight enclosure below (using a plate elevatorthat is not shown in this view) to be captured in the stack. The latches in the input stack122 can also be directed to be released to allow plates to be released from the stack to a 5 plate elevator below (not shown). Window 140 provides an optical path for a bar codereader in fluidic/imaging system enclosure 130 to read bar codes on plates in inputstacker 122. Optionally, a plate stack cover (not shown) may be mounted over the platestack to protect plates in the stacks from the environment. The plate stack cover mayinclude heaters and/or coolers (e.g., a thermoelectric heater/cooler) and/or a desiccant 10 chamber to maintain the plate stack under controlled temperature and/or humidity.

Figure 2 is a view of plate reader 100 without the cover of fluidic/imagingsystem enclosure 130 and plates 105. The view shows sliding light-tight door 150 which provides a light-tight seal to plate introduction apertures in the top of light-tightenclosure 100 located under plate stackers 120 and 122. Motor 155 is coupled via belt 15 to a linear screw drive (not shown) that opens door 150. The views provided of platereader 100 illustrate the use of certain specific translation mechanisms to move avariety of components of the apparatus including door 150; while the specificmechanisms chosen may have certain inventive advantages, the description is notmeant to be limiting and one skilled in the art will be able to select from a variety of 20 conventional single or multiple axis translation mechanisms. It should also 6e notedthat to simplify the drawing, electronic circuit boards are not shown.

Imaging system 160 is mounted on an imaging aperture in the top of light-tightenclosure 110 and can image luminescence from plates in enclosure 110. Pump 170 isa used to drive fluids through the integrated pipetting system. One skilled in the art WO 2008/057111 PCT/US2006/04904!) 17 will be able to select appropriate pumps for use in the system including, but not limitedto diaphragm pumps, peristaltic pumps, and syringe (or piston) pumps (as shown).Pump 170 also comprises a multi-port valve to allow the pump to push and pull fluidsfrom different fluidic lines. Alternatively, multiple pumps can be used to 5 independently control fluidics in different fluidic lines. A bar code reader 180 androtating mirror 185 are used to scan bar codes from plates in input plate stacker 122.Fluidic station 200 is used to deliver sample to the apparatus, wash the integratedpipettor, and dispose of waste from the pipettor. Piercing tool 225 is used to pierce anddisplace seals on wells of sealed plates so as to allow for unblocked imaging of the 10 wells. Pipetting probe translation stage 250 provides horizontal and vertical translationof dual pipetting probe 260.

Figure 3 is another view of plate reader 100 that focuses on the components ofimaging system 160 and shows camera 162 mounted on the top of light-tight enclosure110 via camera bracket 164. Lens 166, coupled to camera 162, is used to provide a 15 focused image of luminescence generated from plates in enclosure 110. Diaphragm168 sealed to lens 166 and an aperture in the top of enclosure 110, and allows imagingsystem 160 to image light from enclosure 110 while maintaining enclosure 110 in alight-tight environment protected from environmental light. Suitable cameras for use inimaging system 160 include, but are not limited to, conventional cameras such as film 20 cameras, CCD cameras, CMOS cameras, and the like. CCD cameras may be cooled tolower electronic noise. Lens 166 is a high numerical aperture lens which may be madefrom glass or injection-molded plastic. The imaging system may be used to image onewell or multiple wells of a plate at a time. The light collection efficiency for imaginglight from a single well is higher than for imaging a group of wells due to the closer WO 2008/057111 PCT/US2006/049049 18 match in the size of the CCD chip and the area being imaged. The reduced size of theimaged area and the increase in collection efficiency allows for the use of smallinexpensive CCD cameras and lenses while maintaining high sensitivity in detection.Particularly advantageous, for their low cost and size, is the use of non-cooled cameras 5 or cameras with minimal cooling (preferably to about -20°C, about -10°C, about 0°C,or higher temperatures).

Figure 4 shows enlarged views of plate seal piercing tool 225, pipettortranslation stage 250, and sample/waste station 300. Pipettor translation stage 250comprises dual probe pipettor 260 which is mounted on motorized vertical translation 10 stage 280 which is, in turn, mounted on horizontal translation stage 270. Horizontaltranslation stage 270 uses a motor and belt drive to move vertical translation stage 280along a linear guide rail, and moves pipettor 260 horizontally between piercing tool 225and sample/waste station 300. Vertical translation stage 280 uses motorized linearscrew drive to raise and lower dual probe pipettor 260. The range of motion allows 15 probes 260 to access fluid in the sample/waste station and to access (through aperturesin the top of light-tight enclosure 110, not shown) wells of plates located in enclosure 110.

Dual probe pipettor 260 includes fluidic connection for connecting both probesto fluidic lines. The use of two probes allows one probe to be used to deliver liquid to 20 the wells and one probe to be used to remove waste. Alternatively, the two probes maybe used to deliver to different reagents from two different fluidic lines. Verticaltranslation stage 280 includes piercing probe translation element 265 which is shaped toslide into slot 227 on piercing tool 225. By using pipettor translation stage 270, probetranslation element may be moved so as to contact and grab piercing probe 225 at slot WO 2008/057ΙΠ PCT/US2006/049049 19 227 via yoke 265. Up and down movement of vertical stage 280 can then be used tocontrol the vertical position of piercing probe 225.

Figure 5 shows two views of sample/waste station 300. Station 300 has threeopen compartments defined on its upper surface: sample compartment 310, waste 5 compartment 320, and washing compartment 330. Sample compartment 310 is influidic connection with fluidic connector 312. Sample delivered to fluidic connector312 (e.g., from an air sampling system) fills sample compartment 310 and is madeavailable to pipettor 260. Waste compartment 320 drains to fluidic connector 322 andprovides a receptacle for pipettor 260 to deliver waste. Washing compartment 330 can 10 be used to wash the surface of pipettor 260; pipettor 260 is inserted in compartment 330and the fluidic system is directed to dispense wash fluid which flows along the outsidesurface of pipettor 260 before overflowing into waste compartment 320.

Compartments 310, 320, and 330 are countersunk into well 305 such that any overflowin compartments 310 and 330 is directed to waste and does not overflow station 300. 15 Fluidic sensors 314 and 324 are included to monitor fluid levels in compartments 310and 320, and ensure proper operation. Suitable fluid sensors include but are not limitedto optical reflectance and capacitance sensors.

Reagent block 340 is simply used to provide a connection between an externalliquid reagent source (connected to fluidic connector 344) and pump 170 (connected to 20 fluidic connector 342). Reagent block 340 is monitored using fluid sensor 346 to ensure delivery of the liquid reagent. The liquid reagent may be omitted if not neededfor a particular application. Non-exclusive examples of possible uses for the liquidreagent include use as a working fluid for the pump and fluid lines, as a wash buffer forwashing assay wells, and/or as a read buffer for providing the optimal environment for WO 2008/057111 PCT/US2006/049049 20 luminescence measurements. In one embodiment, it-is an electrochemiluminescenceread buffer. Waste and liquid buffers may be stored in external or internal bottles.Alternatively, they may be stored in a reagent cartridge, e.g., as described herein.

One skilled in the art will understand that one or more of the functional 5 components in sample/waste station 300 (e.g., one of the compartments, the reagentblock, the sensors, etc.) may be omitted or may be provided in a separate part. Inaddition, the sample compartment may be complemented or replaced by other methodsof providing samples. For example, a tube rack and/or source plate station may beincorporated in the instrument. Such embodiments may be configured so that the travel 10 of probe 260 is sufficient to access such tubes or the wells of such source plates. The rack or plate holder may also have an axis of motion to help provide access to all tubesand wells. In one embodiment, the horizontal motion of the probe in the widthwisedirection (i.e., from side to side relative to the base of the instrument) and movement ofthe tube or plate holder in the lengthwise direction (i.e., from front to back) provides 15 access to arrays of tubes in a tube rack and/or wells held in a source plate in a plate holder.

Figure 6a shows a detailed view of a pipetting probe tip 400 which may be usedon one or both of the probes on pipettor 260. Probe 400 is a hollow tube with a bluntend with slots 410 cut into the tip around the circumference of the probe, allowing for 20 fluid to be aspirating and dispensed from the probe when the probe is in contact with asurface. Rectangular slots are shown, but it is clear that alternative geometries,including triangular or semicircular openings, may also be used. There may be one ormore slots around the circumference of the probe tip. The slots may be arranged in asymmetrical pattern, or the slots may be placed on a particular side of the probe WO 2008/057111 PCT/US2006/049049 21 (asymmetrical) so that liquid is aspirated from a preferred direction, i.e., in order to pullliquid from a meniscus around the bottom edge of the well.

Optionally, the pipetting probes used in the apparatuses are spring loaded sothat they can contact a surface without damaging the surface or the probes. Figures 6b 5 and 6c show liquid dispenser 420 which shows an alternative probe embodiment thatmay be used. Liquid dispenser 420 comprises pipetting probe 424 having vertical tubeelement 425 and probe guide 430 that is configured to allows tube element 425 to movevertically in guide 430 between a fully extended position (Figure 6b) and a fullyretracted position (Figure 6c). As shown, a large diameter region of probe 424 is 10 confined between two position stops defined by inner surfaces of guide 430 althoughone skilled in the art will be able to design alternate configurations of position stops.Dispenser 420 also comprises spring element 440 which is compressed between asurface of guide 430 and ledge (or collar) 435 on vertical tube element 425 so that inthe absence of external force on the bottom of the probe, said tube element stays in the 15 extended position. The dispenser also comprises a vertical translation stage attached toguide 430 (not shown) that allows raising and lowering guide 430.

In one embodiment of a pipetting operation using dispensor 420, guide islowered such that probe 424 is lowered into a container until it touches the bottomsurface. Lowering continues such that tube element 425pushes against spring 440, and 20 retracts into probe guide 430 to a position between the fully extended and fully retracted positions. Fluid is added or removed from the well and probe 424 is raisedout of the well. In a specific example employing a container with a piercable seal, themethod may further comprise lowering the translation stage until probe 424 contactsand pierces the seal. In addition, piercing the seal may further comprise e) lowering the WO 2008/057111 PCT/U S2006/049049 22 translation stage until pipetting probe 424 contacts the plate seal, f) continuing to lowerthe translation stage such that the tube element 425 pushes against spring 440 andretracts into probe guide 430 to the fully retracted position, and g) continuing to lowerthe translation stage such that pipetting probe 424 pierces the plate seal and tube 5 element 425 returns to the fully extended position.

Figures 7a-7b show two views of piercing probe 225 from apparatus 100.

Piercing probe 225 comprises a piercing section 450 with external surfaces that taperto a vertex to form piercing tip 451 at one end of a piercing direction (the direction inwhich the probe moves to pierce a well, in this case the long axis of the probe). 10 Piercing probe 225 also comprises a seal displacement section 452 arranged adjacent topiercing section 450 along the piercing dimension. Displacement section 452 conformsto, but is slightly undersized, relative to the shape of the openings of the wells it isintended to pierce (in this case, square wells with rounded comers). After piercingsection 450 pierces a seal, displacement section 452 pushes the plate seal against the 15 well walls and prevents the seal from interfering with the detection of signals in thewell. Piercing probe 225 also comprises plate stop section 454 adjacent todisplacement section 452. Stop section 454 is sized so that it can not enter the targetwells and thus defines the maximal travel of probe 225 into a target well.

As noted above, displacement section 452 conforms to the shape of the wells it 20 is intended to pierce. The cross-sectional area (perpendicular to the piercing direction)may take on any well shape including, but not limited to, round, elliptical, polygonal(regular or not), and polygonal with rounded comers. In one specific example it issquare or square with rounded edges. Piercing section 450 may take on shapes thatinclude, but are not limited to, conical shapes and pyramidal shapes. As shown in WO 2008/057111 PCT/US2006/049049 23

Figure 7a, it has a square pyramidal shape with edges 453 extending in a radialdirection from tip 451. The edges of the pyramid, advantageously, fonn cutting edgesthat help to cut a seal into sections during a piercing operation. For example, thepiercing probe as shown in Figures 7a-7b is designed to pierce a seal on a rounded 5 square well, cut the seal diagonally to form four triangular seal sections and fold thesesections against the walls of the well. Cutting edges may also be raised from thesurface, e.g., piercing system may be basically conical in shape but have raised cuttingedges that extend from the conical surface. An apparatus is also provided for analyzinga multi-well plate that includes a piercing probe and a sealed plate. Suitable plates 10 include plates sealed with a sealing film (for example, an adhesive, heat sealed, or sonicwelded film). The film may comprise materials including, but not limited to, plasticsand metal films or a combination of both. In one specific embodiment, the seal is ametal foil (which may be coated with a sealing layer such as heat sealable or adhesivecoating or film) such as a heat sealable or adhesive aluminum foil. 15 As shown in Figure 7b, piercing probe 225 is spring loaded to provide a restorative force and to limit the maximum force that can be applied to a plate.

Piercing probe 225 comprises a probe shaft 460 that slides within an aperture in probeguide 470, probe guide 470 being fixedly mounted on the top of light tight enclosure110 (see Figure 2). Compression spring 461 provides a restorative force that biases 20 probe shaft 460 to be full raised into probe guide 470. The restorative force is providedbetween i) pin 464 which is fixedly held in shaft 460 and ii) pin 462 which is fixedlyheld between guide 470 and the top of enclosure 110 but can move freely in slot 463 ofshaft 460 (slot 463 defining the range of motion of probe shaft 460 relative to guide470). Probe 225 is designed to be moved in the piercing direction by application of WO 2008/057111 PCT/US2006/049O49 24 force to plunger 465 (for example, by grabbing slot 227 with probe displacementelement 265 (see Figure 4) and translating probe displacement element 265 in a verticaldirection). A second compression spring (not shown) between plunger 465 and pin 464limits the force that may be applied with piercing probe 225; if excessive force is 5 applied, the plunger will compress the second compression spring instead of movingshaft 460 relative to guide 470. Pin 466 in slot 467 defines the maximal travel ofplunger 465 in shaft 460.

Figure 8 shows alternate embodiments of piercing and pipetting probes that areintegrated into one unit. Figure 8 shows a seal piercer/pipettor 500 that comprises a 10 seal piercing probe 510 having a seal piercing section 520 with a seal piercing tip 521,a seal displacement section 522, and a plate stop section 524. Piercer/pipettor 500 alsocomprises a piercing probe guide 540 having a cylindrical opening in which probe 510can slide along the piercing direction. Piercing probe 510 also has a through-hole 525parallel to the piercing direction and, in one example, off-set from piercing tip 521. 15 Pipette probe 530 is movably-located in through-hole 525 and fixedly attached to guide540 such that movement of piercing probe 510 away from guide 540 causes pipettingprobe 530 to extend from piercing probe 510, and movement of piercing probe 510toward guide 540 causes pipetting probe 530 to withdraw into piercing probe 510.Compression spring 545 in guide 540 acts to push piercing probe 510 away from guide 20 540, and to retract pipetting probe 530 (the maximal displacement of piercing probe 510 being limited by physical stops, specifically collar 526 on probe 510 and ledge 547on guide 540.

In operation, plate guide 540 is lowered toward a sealed well such that piercingprobe 510 pierces and displaces the seal on the well. The spring constant of WO 2008/057111 PCT/US2O06/O49049 25 compression spring 545 is selected such that the seal can be pierced without substantialcompression of spring 545 (and pipetting probe 530 remains retracted in through-hole525 and co-translates with piercing probe 510). Continued lowering of guide 540results in plate stop section 524 contacting the top surface of the well, preventing 5 further translation of piercing probe 510, and resulting in compression of spring 545and extension of pipetting prove 530 into the well.

Figures 9a-9c show top views of light-tight enclosure 110 of apparatus 100 (seeFigures 1-2) after removing most of the components mounted on top of enclosure 110.Figure 9 shows three views (a-c) with sliding light-tight door 150 in three different 10 positions (for clarity, exposed surfaces of door 150 are shown in cross-hatch). InFigure 9a, door 150 is in the fully sealed position so as to fully seal plate introductionapertures 626, piercing probe aperture 630, and pipetting probe apertures 640 in the topof enclosure 110. Light detection aperture 610 is unblocked allowing detection and/orimaging of light emitted from wells positioned underneath aperture 610. This view also 15 shows plate contact mechanism 615 mounted on the bottom of enclosure 110 underaperture 610. Plate contact mechanism 615 is designed for use with plates havingelectrodes within the wells and electrode contacts to these electrodes patterned on thebottom of the plates; plate contact mechanism 615 providing electrical contact to theelectrode contacts of the wells positioned under aperture 610. 20 In Figure 9b, sliding door 150 is partially opened to align piercing probe and pipetting probe apertures in sliding door 150 with corresponding apertures 630 and 640in the top of enclosure 110. With the door in this position, the piercing and pipettingprobes can access wells positioned under the appropriate apertures. Multiple pipettingapertures are provided so that a pipetting probe can access multiple locations in a well WO 2008/057111 PCT/US2006/049049 26 or multiple wells in plate without repositioning the plate. In Figure 9c, sliding door 150is fully opened, fully opening plate introduction apertures 626 and allowing the transfer t of plates between plate stackers 120 and 122, and plate elevator 625.

Figure 10 shows the mechanical components present in light-tight enclosure 5 110. Plate translation stage 710 is mounted at an elevated position within enclosure 110, and provides a plate holder 720 and holding plate 730. Translation stage 710comprises linear guides and motors that provide two horizontal axis of translation toplate holder 720, and allows plate holder 720 to cover most of the horizontal area withenclosure 110. Plate holder 720 supports plate 730 at the edges and is open in the 10 center so that plate elevator 740 and contact mechanism 750 may contact the bottom ofplate 730 through plate holder 720. When plate holder 720 is positioned over one ofplatforms 745 on elevator 740, the motor driven scissor mechanism of elevator 740may operate to raise the platform, and lift plate 730 from plate holder 720 and up to aplate stacker mounted on the top of enclosure 110. Similarly, when plate holder 720 is 15 positioned over contact mechanism 750, the motor driven scissor mechanism of contactmechanism 750 may operate to raise electrical contacts 755 so that they contactelectrode contacts on the bottom of plate 730, and allow application of electricalenergy, through said contacts, to electrodes in the wells of plate 730, for example, to induce electrochemiluminescence at those electrodes. It should be noted that the 20 motion systems described for moving plates, electrical contacts, probes, etc. are notlimited to the specific mechanisms depicted herein, although these mechanisms mayhave specific advantages. It is well within the purview of one in the art to select otherconventional mechanism for accomplishing the desired movement of components. 192157/2 27

In one embodiment, translation stage 710 may be used to achieve rapid one or two axis oscillation of plate holder 720 and, thereby, to shake and mix the contents of a plate on the plate holder. The shaking profiles can range from continuous single-axis shaking to duty-cycled orbital shaking. One example includes shaking with the axes at 5 two different frequencies. The system may also provide for sonication to enhance mixing during sample incubation, for example, as described in the U.S. Patent No. 6,413,783 of Wohlstadter et al.

In one embodiment, the light tight enclosure includes a light source located underneath the imaging aperture and below the elevation of the plate holder. This 10 arrangement allows for the use of fiducial holes or windows in plates to be used to correct for errors in plate alignment. Light from the light source is passed through thefiducials and imaged on the imaging system so as to determine and correct for thealignment of the plate. Advantageously, plates formed from plate bottoms mated to a platetop (e.g., plates with screen printed plate bottoms mated to injection-molded plate 15 tops as described in U.S. Patent Nos. 7,842,246 and 6,977,722) advantageously include fiducials patterned (e.g., screen printed) or cut into the platebottom to correct for misalignment of the plate bottom relative to the plate top. In onespecific embodiment, the plate top on such a plate includes holes (e.g., in the outsideframe of the plate top) aligned with fiducials on the plate bottom to allow imaging of 20 the fiducials. Accordingly, the imaging of light generated under a plate may be used tocommunicate the exact position of the plate to the image processing software and also toprovide for a camera focus check. The plate may then be realigned using a two-axispositioning system. Thus, a plate positioning method is provided comprising: (1) providinga plate having light-path openings; (2) illuminating plate from the bottom; (3) WO 2008/057111 PCT/US2006/049049 28 detecting light coming through light-path openings; and (4) optionally, realigning theplate.

The apparatuses, systems, method, reagents, and kits may be used forconducting assays on environmental samples. They may be particularly well-suited forconducting automated sampling, sample preparation, and analysis in the multi-wellplate assay format.

One embodiment is an autonomous environmental monitoring systemcomprising (1) a sample collection module; (2) optionally, a sample processing module;and (3) a biological agent detection module, wherein the modules are fluidicallyconnected, or in one example connectable, to allow for sample transfer betweenmodules. According to one embodiment, an autonomous environmental system allowsfor multi-week periods of sustained operation requiring reduced human interaction.

The biological agents that may be detected include viral, bacterial, fungal, andparasitic pathogens as well as biological toxins. The agents themselves may bedetected or they may be detected through measurement of materials derived from theagents including, but not limited to, cellular fragments, proteins, nucleic acids, lipids,polysaccharides, and toxins.

In one embodiment, the autonomous environmental monitoring system samplesair, suspends particulate matter from the air sample in a collection fluid therebycreating a liquid sample, and performs an assay for one or more biological agentsincluding viruses, bacteria, and toxins. The assay can be conducted in a singular ormultiplexed assay format.

Some examples of biological agents include, but are not limited to, vacciniavirus, Brucella spp., botulinum toxin A, ricin, staph enterotoxin B (SEB), Venezuelan WO 2008/057111 PCT/US2006/049049 29 equine encephalitis (VEE), Yersinia pestis (YP), Bacillus anthracis (BA), Coxiellaburnetii (CB), and Francisella tularensis (FT).

In one embodiment, the system also comprises a computer that receives andprocesses data from a biological agent detection module. The computer recognizes in 5 the data the positive identifications and, optionally, increases the frequency ofconducting tests, transmits the data to alert the appropriate authorities, and further,optionally, automatically alerts nearby additional autonomous environmentalmonitoring system which automatically increase frequency of analysis and/or lowerdetection limits to identify presence of biological agents. 10 Thus, a network is also provided of autonomous environmental monitoring systems. According to one embodiment, each autonomous environmental monitoringsystem in the network may automatically determine individualized detection thresholdlimits by accounting for the background data at individual sites through acquiringsampling of the background at that specific location over the period of operation. The 15 acquired background level information is used to track average background level andthe standard deviations of the background level, and dynamically adjust the detection threshdlds limit for a site location of an individual autonomous environmental monitoring system.

According to one embodiment, a sample collection module is capable of 20 collecting and processing environmental samples such as suspensions of particles filtered, or otherwise concentrated, out of air samples. Air sampling systems that maybe used include filter based collectors, impactors, virtual impactors, and wettedcyclones. Examples of standard sample collection modules that can be used includesystems described in U.S. Patents 6,888,085; 6,887,710; 6,867,044; and 6,567,008. WO 2008/057111 PCT/US2006/049049 30

Additionally, or alternatively, the sample collection module may be configured tocollect, concentrate, and/or process other classes of samples such as water samples, soilsamples, clinical samples, environmental swipes, etc., environmental sludges, foodsamples, beverages, samples that comprise suspensions of dirt, or biological samples. 5 Clinical samples that may be analyzed include, but are not limited to, feces, mucosalswabs, physiological fluids and/or samples containing suspensions of cells. Specificexamples of biological samples include blood, serum, plasma, tissue aspirates, tissuehomogenates, cell cultures, cell culture supernatants (including cultures of eukaryoticand prokaryotic cells), urine, and cerebrospinal fluid. 10 A device for suspending particulate contained in the aerosolized particulate stream in a collection fluid may utilize a sonicator, a vortex mixer, a shaker, a simplemixer, or other means for optimizing contact between a fluid and an air sample.

According to one embodiment, a surfactant can be added to the collection fluidto prevent loss of biological agents to particles (including, but not limited to, paper, 15 debris, and dust) in the collector solution. Useful surfactants include, but are notlimited to ionic or non-ionic detergents or surfactants (e.g., classes of non-ionicdetergents/surfactants are known by the trade names of BRJJ, TRITON, TWEEN,THESIT, LUBROL, GENAPOL, PLURONIC, TETRONIC, and SPAN). According toanother embodiment, biological agents adsorbed on particulate, for example cellulose- 20 based debris, are released back into solution by treatment with a carboxylic acid, forexample, acetic acid, or citric acid.

According to one embodiment, detection of biological agents is improved byphysical or chemical processing of the sample. The processing can be used to (1) WO 2008/057111 PCT/US2006/049049 31 concentrate biological agents in the sample, (2) lyse and/or fragment the biologicalagents, and (3) expose binding sites that would otherwise remain inaccessible. A device may include a concentrator system to concentrates biological agentssuspended in the liquid sample by filtration, affinity separation and/or centrifugation. 5 The filtration concentrator system may employ a filter selected to retain bacterial andviral particles while excising excess fluid. In one example, filtration concentratorsystem employs filters that retain biological molecules, such as proteins, toxins, nucleicacids, polysaccharides, and lipids. The system may also provide for biological agentremoval from the filter and re-suspended in solution, for example by flowing buffer 10 solution in the reverse direction and/or sonication.

The centrifugation concentrator system separates biological agents from thefluid by removing excess fluid following the centrifugation. The system also providesfor re-suspension of the concentrated biological agents in a smaller volume of fluidfollowing excess fluid removal. 15 According to one embodiment, the system employs affinity concentration unit comprising an affinity resin capable of binding to biological agents. Examples of theaffinity resin include, but are not limited to, hydrophobic interaction resins (C4-C18,poly-, polyethyl-, and polymethyl-aspartamide). The resin can be convenientlypackaged in columns, cartridges, or used as loose beads. The system provides for 20 biological agents removal from the affinity media by elution with a release solvent.

According to one embodiment, at least one analyte can be concentrated through immobilization on the surface of at least one microparticle, or a plurality ofmicroparticles (for example, a plurality of magnetically responsive microparticles),either passively (e.g., by non-specific binding) or via binding interactions with a WO 2008/057111 PCT/US2006/049049 32 binding partner of the analyte (e.g., an antibody that binds the analyte) or via chemicallinkage such as via covalent bonds (e.g., reaction with an NHS-ester) and/or by reactionwith an appropriate linker, or via one or more specific binding reagents, and/or by a combination thereof. 5 In one embodiment, an ultrasonic lysis system is incorporated into the sample processing module, e.g., a system as described in U.S. Patent 6,413,873 of Wohlstadteret al. Alternatively, the sample processing module may comprise a chemical lysissystem. Chemical lysis by detergents, acids, bases, or other lysing agents can be usedto break open vegetative bacteria, spores, and viral particles. An acidic or basic 10 solution used for chemical lysis can then be neutralized prior to sample delivery to theanalyte detection module. According to one embodiment, lysis system is incorporatedupstream of a separator comprising a concentrator system. Alternatively, lysis followsremoval of biological agents from a concentrator unit.

The sample processing module may further include a partial purification 15 system, capable of removal of undesirable and in some examples interfering matter.

For example, the partial purification system may include a filter permeable tobiological molecules, but impervious to large particulate. The module may also includea chemical partial purification system (for example, a system for precipitating nucleicacids using alcohols). 20 According to one embodiment, a biological agent detection module comprises a reader for reading electrochemiluninescence (ECL) from multi-well plates. Forexample, ECL-based multiplexed testing is described in U.S. Publications2004/0022677 and 2004/0052646 of U.S. Applications 10/185,274 and 10/185,363,respectively; U.S. Publication 2003/0207290 of U.S. Application 10/238,960; U.S. WO 2008/057111 PCT/US2006/049049 33

Publication 2003/0113713 ofU.S. Application 10/238,391; U.S. Publication2004/0189311 ofU.S. Application 10/744,726; and U.S. Publication 2005/0142033 ofU.S. Application 10/980,198.

In one embodiment, the biological agent detection module has an integrated 5 pipettor and a fluidic manifold for receiving samples and buffers, and distributing themto the wells of a plate. According to one preferred embodiment, the module allows toinduce and measure ECL from only one well at a time.

One example of the analyte detection module, picture in Figure 1, demonstratesthe arrangement in a compact instrument of a mechanical system for storing and 10 moving plates, a light detector for measuring luminescence (including ECL), a fluidicinterface and pipetting system for transferring samples to the plates, and the electronic boards that drive the module.

According to one embodiment, the analyte detection module has threesubsystems: (1) light detection, (2) liquid handling, and (3) plate handling. Each 15 subsystem may, optionally, have a built-in error detection component to ensure reliableoperation and to reduce the probability of false positives. A method is also provided for conducting assays for biological agents including,but not limited to, biological warfare agents. In one embodiment, the method is abinding assay. In another embodiment, the method is a solid-phase binding assay (in 20 one example, a solid phase immunoassay) and comprises contacting an assay composition with one or more binding surfaces that bind analytes of interest (or theirbinding competitors) present in the assay composition. The method may also includecontacting the assay composition with one or more detection reagents capable ofspecifically binding with the analytes of interest. The multiplexed binding assay WO 2008/057111 PCT/US2006/049049 34 methods according to preferred embodiments can involve a number of formatsavailable in the art. Suitable assay methods include sandwich or competitive bindingassays format. Examples of sandwich immunoassays are described in U.S. Patents4,168,146 and 4,366,241. Examples of competitive immunoassays include those 5 disclosed in U.S. Patents 4,235,601; 4,442,204; and 5,208,535 to Buechler et al. In oneexample, small molecule toxins such as marine and fungal toxins can beadvantageously measured in competitive immunoassay formats.

Binding reagents that can be used as detection reagents, the binding componentsof binding surfaces and/or bridging reagents include, but are not limited to, antibodies, 10 receptors, ligands, haptens, antigens, epitopes, mimitopes, aptamers, hybridizationpartners, and intercalaters. Suitable binding reagent compositions include, but are notlimited to, proteins, nucleic acids, drugs, steroids, hormones, lipids, polysaccharides,and combinations thereof. The term “antibody” includes intact antibody molecules(including hybrid antibodies assembled by in vitro re-association of antibody subunits), 15 antibody fragments, and recombinant protein constructs comprising an antigen bindingdomain of an antibody (as described, e.g., in Porter & Weir, J.Cell Physiol,, 67 (Suppl1):51-64,1966; Hochman et al., Biochemistry 12:1130-1135,1973; herebyincorporated by reference). The term also includes intact antibody molecules, antibodyfragments, and antibody constructs that have been chemically modified, e.g., by the 20 introduction of a label.

Measured, as used herein, is understood to encompass quantitative andqualitative measurement, and encompasses measurements earned out for a variety ofpurposes including, but not limited to, detecting the presence of an analyte, quantitatingthe amount of an analyte, identifying a known analyte, and/or determining the identity WO 2008/057111 PCT/US2006/049049 35 of an unknown analyte in a sample. According to one embodiment, the amounts thefirst binding reagent and the second binding reagent bound to one or more bindingsurfaces may be presented as a concentration value of the analytes in a sample, i.e., theamount of each analyte per volume of sample. 5 Analytes may be detected using electrochemiluminescence-based assay formats.

Electrochemiluminescence measurements are preferably carried out using bindingreagents immobilized or otherwise collected on an electrode surface. Especiallypreferred electrodes include screen-printed carbon ink electrodes which may bepatterned on the bottom of specially designed cartridges and/or multi-well plates (e.g., 10 24-, 96-, 384- etc. well plates). Electrochemiluminescence from ECL labels on the surface of the carbon electrodes is induced and measured using an imaging plate readeras described in copending U.S. Applications 10/185,274 and 10/185,363 (both entitled“Assay Plates, Reader Systems and Methods for Luminescence Test Measurements”,filed on June 28, 2002, hereby incorporated by reference). Analogous plates and plate 15 readers are now commercially available (MULTI-SPOT® and MULTI-ARRAY™plates and SECTOR® instruments, Meso Scale Discovery, a division of Meso ScaleDiagnostics, LLC, Gaithersburg, MD).

In one embodiment, antibodies that are immobilized on the electrodes within theplates may be used to detect the selected biological agent in a sandwich immunoassay 20 format. In another embodiment, microarrays of antibodies, patterned on integratedelectrodes within the plates, will be used to detect the plurality of the selectedbiological agents in a sandwich immunoassay format. Accordingly, each well containsone or more capture antibodies immobilized on the working electrode of the plate and,optionally, in dry form labeled detection antibodies and all additional reagents WO 2008/057111 PCT/US2006/049049 36 necessary for analysis of samples, and for carrying out positive and negative controls.

In one example, arrays having multiple binding surfaces within a single well allow toreplicate tests to significantly reduce false positive identification. A positive control method is provided to identify conditions or samples that 5 may cause false negative measurements by interfering with the generation of signal.According to this aspect, positive control method comprises contacting sample with abinding reagent (e.g., an antibody) to a positive control substance (for example, to anon-toxic positive control substance) that is not expected to be observed inenvironmental samples; then contacting the sample with a labeled detection reagent (for 10 example, an antibody) against the positive control substance and a controlled amount ofthe positive control substance, and measuring the signal. The positive control should,therefore, always provide a constant positive signal regardless of the sample. Asignificantly reduced signal may indicate that the sample interferes with the antibodybinding reactions or the signal generating process, or may indicate a malfunction in the 15 plate or instrument. A negative control method is provided employing a capture reagent (e.g., anantibody) that is not matched with a detection reagent. The method comprisescontacting a sample with a capture reagent in the presence of mismatched detectionreagent and measuring signal. The negative control should, therefore, provide a 20 negative signal regardless of the sample. A significantly elevated signal from thenegative control indicates the presence of a material in the sample, such as a cross-linking agent, that is causing the non-specific binding of non-matched detectionreagents to the negative control capture reagent. WO 2008/057111 PCT/US2006/049049 37 A method is provided using a mixture of non-specific antibodies from the samespecies (e.g., polyclonal mouse, rabbit, goat, etc.) as specific capture antibodies toidentify any non-specific binding effects that would otherwise provide false positiveidentification. This mixture may be selected to include the species of the antibodies 5 used in the actual test measurements. A method is provided using at least two different pairs of capture and detectionreagents (e.g., antibodies) in alternating independently addressable wells to reduce thefrequency of false positive identifications. Accordingly, the first binding reagent pair isused as a primary identification, which, if positive, triggers the confirmation test using 10 the second binding reagent pair. The pairs may target the same marker or epitopes of abiological agent or, alternatively, they may further increase the orthogonality of the twomeasurements by targeting different markers or epitopes of a biological agent. Anarrangement of at least two different antibody pairs in alternating well may beparticularly advantageous. According to this aspect, the pairs are alternating as a 15 primary identification set, thereby eliminating the need to dedicate wells as confirmation tests. Instead, if a sample is suspected to be positive based on.the mostrecent test (based on either the first or the second pair), confirmation is simplyperformed by running the subsequent test well.

The reliability of detection method may be further improved by providing two 20 or more different capture antibodies in a single well, wherein (a) the two or moredifferent antibodies recognize the same marker and/or epitope of the same biologicaltarget; and/or b) the two or more different antibodies recognize different markers and/orepitopes of the same biological target. WO 2008/057111 PCT/US2006/049049 38

One method for the detection of biological agents comprises (1) collecting anair sample using sample collection module (by the way of example, collecting aerosolsin an air sample by using integrated an aerosol sampling system); (2) suspending theaerosols in a liquid; (3) optionally, transferring the aerosol suspension into a sample 5 processing module; (4) optionally, concentrating and/or partially purifying the aerosolin the sample processing module (by the way of example, partially purifying byremoving large particles); (5) transferring a liquid sample to a well of a multi-wellplate, (6) adding at least one detection antibody against the same agents; (7) conductingan assay measurement and identifying samples that are positive for a biological agent; 10 (8) optionally, performing a confirmation test by repeating (5)-(7); and (9) issuing an alert warning. Optionally, detection reagents are present in the wells in dry form and(6) may be omitted. In this case, addition of the sample results in reconstitution of thedried reagents. In one embodiment, step (5) includes transferring the sample to the wellthrough the use of an integrated pipetting system. 15 Step (5) may comprise pumping the liquid sample into a sample chamber (e.g., sample compartment 310 of instrument 100) and using a pipetting system (e.g., probe260 of instrument 100) to transfer the sample to a well of a plate ), e.g,, a plate in light-tight enclosure 110 of instrument 100). In one embodiment, instrument 100 asdescribed above is used to carry out this operation as well as one or more (or all) of the 20 subsequent analysis steps ((6)-(9)).

In one embodiment, the plate has an immobilized array of binding reagents (e.g., antibodies or nucleic acids) and bioagents in the sample bind to the correspondingimmobilized reagent and a corresponding labeled detection reagent to form a sandwichcomplex. In some, the array is formed on an electrode and detection is carried out WO 2008/057111 PCT/US2006/049O49 39 using an ECL measurement. In one embodiment, after addition of an ECL read buffer,labels on the electrode are induced to emit ECL by applying a voltage to the workingelectrode, and the emitted ECL is imaged with a CCD camera. Optionally, washingmay be added prior to the ECL measurement to provide advantages in assay sensitivity, 5 particularly for optically turbid samples generated by aerosol samplers in dirty environments. Image analysis is used to determine the location of the emitted light onthe array and, thus, the identity of the agents in the sample. Image analysis alsoprovides the intensity of the emitted light from each element of the antibody array andallows for precise quantitation of each bioagent. to Patents, patent applications, and publications cited in this disclosure are incorporated by reference in their entirety.

The present invention is not to be limited in scope by the specific embodimentsdescribed herein. Indeed, various modifications of the invention in addition to thosedescribed herein will become apparent to those skilled in the art from the foregoing 15 description and accompanying drawings. Such modifications are intended to fall withinthe scope of the claims. A claim which recites "comprising” allows the inclusion of other elements to bewithin the scope of the claim; the invention is also described by such claims reciting thetransitional phrases “consisting essentially of’ (i.e., allowing the inclusion of other 20 elements to be within the scope of the claim if they do not materially affect operation ofthe invention) or “consisting of* (i.e., allowing only the elements listed in the claimother than impurities or inconsequential activities which are ordinarily associated withthe invention) instead of the “comprising” term. Any of these three transitions can be used to claim the invention. CTOD&ran PPU/a , DTixan rw:n οτα inia^o pnow pnizn irn πτ qaoa,Ρ’ηη ηχΰ" laoana ma’na no^maa np’-ion .zruwan rwao mpnan ρπίΛ oxnmοιηπη Pi?

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