Surface Plasmon Resonance (SPR) phenomena may be used in conjunction with interrogation of a microarray carrying a variety of reactive or potentially reactive regions of interest (ROI)s. SPR is an advanced optical technology that measures changes in refractive index caused by the binding of molecules to a reflective surface. SPR has developed into a powerful tool in the bioanalytical field to measure binding constants—a critically important variable in understanding how effectively two biomolecular compounds bind to one another. For instance, SPR can observe how well a drug compound binds to a target molecule of interest.
SPR has the ability to generate a binding constant of a biomolecular interaction because it can measure the kinetics of the interaction. This may allow a researcher to view the moment at which an agent begins to bind, as well as when, or whether, the compounds disassociate. Such sensitivity may allow a researcher to view weak binding interactions—biomolecular interactions in which two species bind to one another, turn on a signal pathway, and quickly dissociate. The observation of these biomolecular binding events is a key element in biochemical and pharmaceutical research and development.
According to an embodiment, an SPR analysis apparatus may include a modular, compartmentalized design configured with separate volumes for modules having disparate environmental constraints.
According to an embodiment, an SPR analysis apparatus may include one or more fluid reservoirs equipped with a non-contact fluid level sensor.
According to an embodiment, a prism mounting assembly for an SPR optics module may include a spill plate substantially sealed and including at least one spill well configured to substantially prevent spilled liquid from entering the SPR optics module.
According to an embodiment, a prism mounting assembly for an SPR optics module may include a plurality of pins aligned to register at least two lower surfaces of a prism.
According to an embodiment, a flow cell module for an SPR analysis apparatus may include a thermoelectric heater-cooler configured to maintain a selected temperature of fluids flowing through an SPR flow cell.
According to an embodiment, a method for mounting a flow cell in an SPR analysis apparatus may include coupling the flow cell into a flow cell carrier and coupling the flow cell carrier into a flow cell mounting assembly.
According to an embodiment, an SPR flow cell may include a top plate having orifices configured for ingress and egress of fluids to and from the flow cell.
According to an embodiment, an SPR analysis system may include a prism having a relatively high refractive index configured to couple to a microarray substrate having a relatively low refractive index.
The following discussion is presented to enable a person skilled in the art to make and use the claimed invention. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the generic principles herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention as defined by the appended claims. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein.
In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. Other embodiments may be used and/or and other changes may be made without departing from the spirit or scope of the disclosure.
The SPR analysis apparatus 101 is configured to detect and/or characterize molecular binding interactions in a label-free format. The optics assembly 108 may simultaneously address thousands of spots on the microarray. Each spot may provide sensitivity to a particular chemical or biochemical binding event. The first component of the binding pair (also referred to as a ligand) is typically immobilized on the microarray and the second component of the binding pair, typically referred to as an analyte, is flowed past the microarray through a flow cell volume. Typically, the second component of the binding pair may be pumped from a microwell via the autosampler. The chemical binding pairs may include, for example, an antigen-antibody pair, a peptide-peptide pair, a protein-DNA pair, a protein-RNA pair, or complementary strands of DNA or RNA.
The SPR analysis apparatus 101 may be used to determine a range of scientifically valuable observations. For example, specificity of binding pairs may be used to identify unknown molecules in a sample. Kinetic rate parameters, such as an association constant (ka) that characterizes association of an analyte with a ligand and a dissociation constant (kd) that characterizes dissociation of an analyte from a ligand may be determined. Binding affinity, e.g., the strength of the binding interactions, such as may be characterized by an equilibrium constant Ka=ka/kd may also be determined.
The SPR analysis apparatus 101 may provide label-free detection. In contrast to other systems that use tagged molecules, label-free detection may use an unaltered analyte. This may be useful compared to labeled systems in that steric hinderance, binding affinities, and other functional aspects of the analyte are typically not altered by the addition of a molecular tag. Especially in the case of unknown analytes, label-free detection also allows detection of unknown molecules without requiring a priori functionalization or otherwise reacting the unknown molecules to add molecular tags.
The SPR analysis apparatus 101 may also be configured to provide high-throughput analysis with up to or greater than about 5,000 simultaneous data points per run. The high-throughput may be leveraged to provide high-content analysis with up to 5,000 unique ligands per microarray. That is, the system 101 may be configured to interrogate microarrays with each ROI holding a unique ligand having a corresponding unique affinity for analytes.
An electronics module 208 includes a microprocessor and/or microcontroller, memory, communications hardware, sensor interfaces, driver electronics, a power supply, and other components configured to interface with other portions of the SPR analysis apparatus 101, 201.
The fluid supply volume 104 includes room for seven reagent bottles 206 (
The electronics module 208 includes control circuitry coupled to receive control data from the computer system 302 and responsively control other portions of the SPR analysis apparatus 101, including an autosampler 204, a fluidics module 210, and an optics module 108. The electronics module 208 may include a conventional microprocessor-based controller including memory (e.g., RAM, ROM, etc.), a microprocessor, input/output circuitry, user interface hardware, one or more ASICs, one or more gate arrays or FPGAs, programmable array logic (e.g., PAL, etc.), one or more analog-to-digital converters, one or more digital-to-analog converters, one or more motor drivers, one or more sensor interfaces, and/or other devices in operative communication via one or more buses and physically connected using a printed circuit board.
The electronics module 208 of the SPR analysis apparatus 101, 201 includes one or more thermal control modules 304 for one or more of the flow cell modules 106 and the optics module 108. A second thermal control module 306 (which may optionally be integrated with the thermal control module 304) may provide temperature control for the well plate sample array of the autosampler 204. SPR operates by measuring the response of photon reflectivity vs. conversion from photons to surface plasmons responsive to small variations in local refractive index that result from binding (or not) and unbinding of an analyte from an immobilized ligand. Since the refractive index of fluids typically varies according to temperature, accurate and precise temperature control may be important.
Typically, one or more thermocouples, thermisters, or other temperature measurement apparatuses may be located in thermal contact with components of each of the flow cell 106, optics module 108, and well plate of the autosampler 204. The autosampler 204 well plate and the flow cell 106 may be thermostatically controlled to common desired fluid temperature. Alternatively, the autosampler 204 well plate may be controlled to a temperature that is offset from the flow cell 106 to compensate for systematic changes in temperature during delivery of the fluids from the well plate to the flow cell. Optionally, the autosampler 204 pipet, tubing and/or components in the fluidics module 210, other reagents 206 in the fluid supply volume 104, and tubing between the fluidics module 210 and flow cell module 106 may include temperature measurement and/or control apparatuses that are controlled by a thermal control module 304 and/or 306. The optics module 108 may be thermostatically controlled to maintain the same temperature as the flow cell module 106. According to an embodiment, the optics module 108 may be thermostatically controlled to a temperature slightly higher than the temperature of the fluids, for example 1° to 2° Celsius higher than the temperature of the fluids in the flow cell 326, to avoid condensation on optical surfaces.
The thermal control modules 304 and 306 may operate to heat and/or cool the autosampler 204, flow cell module 106, and optics module 108. For example, for operation above ambient temperature, thermal control may be performed by selectively heating components. According to an embodiment, a thermo-electric (TE) heater/cooler may be used to heat or cool the components. In some cases, energy from the light source 308 may provide radiant heating of the optics module 108 and/or the flow cell module 106. In cases where radiant heating is significant, at least some surfaces may be cooled while other surfaces are heated. For example, the autosampler 204 sample well may be heated, and the flow cell module 106 may be cooled to maintain a consistent temperature between the components. As an alternative to local TE heating/cooling, the flow cell module 106 and/or other temperature-controlled components may be heated or cooled by a circulating fluid that is maintained at a controlled temperature by a remote temperature control apparatus that is controlled by temperature control module or modules 304 and/or 306.
Three TE heater/coolers are respectively located above the flow cell in the flow cell module 106, beneath the well plate in the autosampler 204, and in the optics compartment 108. Temperature values may be set between 4° C. and 40° C. using a method setup function in an apparatus control software application running on the computer 302. To ensure the samples and buffer entering the flow cell are at the same temperature, tubing between the injection valve 346 and the flow cell 326 has a thin lining and is constructed from a heat-conducting material. All fluids are first circulated through this tubing along the TE heater/cooler before entering the flow cell 326.
A TE heater/cooler located in the optics compartment 108 may speed up system warm-up time. If the system is turned on from a cold state, the optical components such as the camera and LED light source will heat up until they reach equilibrium. The heater speeds the process of reaching temperature equilibrium, which is necessary for a stable baseline.
The optics module 108, including a light source 308, a camera 310, and one or more drive motors 312 are controlled by an optics drive control module 314 in the electronics module 208. The light source 308 and collimation and/or polarizing optics 316 are configured to provide substantially collimated illumination 318. An optical coupler 320, which may be a flat or curved surface prism having an optical coupler refractive index, for example, is aligned to receive the illumination beam 318. The optical coupler 320 couples rays of the beam 318 to corresponding points on an SPR coupling surface (not shown) of a microarray 322. Optionally, a coupling fluid, gel, or film 324 is disposed between the optical coupler 320 and the microarray 322 to eliminate air surfaces and reduce corresponding insertion losses. The one or more drive motors 312 drive the light source 308 and camera 310 to respective incident and reflection angles θ and θ′, which nominally are set equal to one another.
U.S. patent application Ser. No. 11/562,197 (attorney docket number 2648-005-03), entitled “SURFACE PLASMON RESONANCE SPECTROMETER WITH AN ACTUATOR DRIVE ANGLE SCANNING MECHANISM”, invented by Hann-Wen Guan, et al., filed Nov. 21, 2006, is to the extent not conflicting with this disclosure, incorporated by reference herein. This application includes information about angle control and actuation of an SPR optics module 108, according to an embodiment.
Typically, the microarray 322 includes a substrate (not shown) having a substrate refractive index, the substrate supporting the SPR coupling surface. Typically, the SPR coupling surface is a thin metal film, often gold, that is thin enough for an evanescent wave portion of the impinging beam to penetrate through to a region extending about 200 μM above the top surface of the SPR coupling surface. (The orientation of the optics module 108, the microarray 322, and the flow cell module 106 may be reversed, rotated, or may otherwise differ from the depiction of
Ligands are typically covalently bound to the upper surface of the SPR coupling surface (or to one or more binding layers such as a thin layer of titanium, titanium dioxide, and/or a self-assembled monolayer (SAM)) in a pattern of regions of interest (ROIs). The ligands include functionalized portions that preferentially bind to one or more analytes or potential analytes, the ligands and the functionalized portions typically lying well within the evanescent wave penetration. For example, a first ligand located in a first ROI may preferentially bind to a first protein or other molecule, (first analyte) and a second ligand located in a second ROI may preferentially bind to a second protein or other molecule (second analyte). When the first analyte is present in fluid flowing through the flow cell 326 over the surface of the microarray 322, at least a portion of the first analyte binds to the first ligand in the first ROI. If the second analyte is missing from the fluid, then substantially no binding to the second ROI may occur. The presence of the first analyte bound to the first ROI typically lowers the refractive index in the region of the evanescent penetration, while the lack of the second analyte bound to the second ROI keeps the ROI at a value similar to the bulk fluid. Rays of the beam 318 that evanescently penetrate into the region above the first ROI thus encounter a lower refractive index than rays that penetrate into the region above the second ROI. The higher refractive index of the second ROI tends to reflect the impinging photons of the beam 318. The lower refractive index of the first ROI tends to cause conversion of the photons to surface plasmons, thus reducing the apparent reflectivity of the first ROI.
Since the refractive index dip is proportional to analyte loading on the ROI, the reflectivity of the ROIs (e.g. in steady state) may indicate an analyte presence or concentration in the fluid. Similarly, the reflectivity may be monitored vs. time to detect the rate of analyte binding characterized by an association constant ka or a rate of analyte unbinding characterized by a dissociation constant kd. Similarly, the reflectivity of the ROI may indicate an equilibrium constant Ka=ka/kd.
The intensity of reflected rays may be modulated according to the local indices of refraction within regions of interest (ROIs) (not shown) on the top surface of the SPR coupling surface of the microarray 322. Reflected light 328 is then launched from the optical coupler 320 through imaging optics 330 to a detector 310. According to an embodiment, the detector 310, which may be referred to as a camera, may include a focal plane detector such as a charge-coupled device (CCD) or complementary metal-oxide semiconductor (CMOS) imager array. The camera 310 outputs a corresponding detection signal or detection data (not shown) such as an electrical detection signal or detection data that is transmitted to the electronics module 208 and from the electronics module 208 to the computer system 302. According to an embodiment, signals or data from the camera 310 are passed through the electronics module 208 with minimal or no signal conditioning in order to best preserve the original reflected light values received by the camera 310.
The detection signal or data signal from the camera 310 may be processed by the computer system 302 to generate a bitmapped, vector, or other image of the reflection pattern of the SPR coupling surface of the microarray 322. According to an embodiment, the signal from the camera 310 is returned as a video data stream that is received by a video processing circuit board in the computer system 302 and managed by an SPR system control application running on the computer 302.
The precision and accuracy of the video output by the camera is a function of the stability of the light source 308. A light source monitor module 332 in the electronics module 208 monitors the status of the light source 308. The light source monitor module 332 may monitor electrical current dissipated by the light source 308, temperature of the light source 308, and/or may monitor light energy emitted by the light source, for example by using a photodiode or phototransistor coupled to a light tap. The light source monitor module 332 may provide data related to the operation of the light source 308 to the computer system 302 and/or to a user interface 334. According to an embodiment, the light source monitor module 332 may include a feedback or feed-forward control circuit, for example including a proportional-integral-differential (PID) controller, to drive the light source 308 to a constant and/or desired light output. Some embodiments include a variable-output source such as an incandescent source in the light source 308. According to an embodiment, the light source module 308 is a light-emitting diode (LED) light source configured to output a narrow wavelength range with substantially constant output. According to an embodiment the LED light source 308 may be configured to output one or more wavelengths in the red and/or infrared wavelength range. According to an embodiment, the LED light source is configured to output light at one or more of about 633, 635, 655, 670, 720, 780, 850, 880, 910, and/or 940 nanometers wavelength.
The electronics module 208 is further configured to control the movement and selection of fluids for flow through the flow cell 326. A pump control module 336 is configured to control and drive pumps 338 and 340 in the fluidics module 210. A valve control module 342 is configured to control and drive valves including a sample injection valve 344, a selection valve 346, and a reagent selector valve 348, the latter being configured to select from among reagents 206 such as buffer solution or water. An autosampler control module 350 is configured to control the autosampler 204. The fluidics subsystem 210, including approaches to its control, is described in U.S. patent application Ser. No. 12/339,017, entitled “SPR APPARATUS WITH A HIGH PERFORMANCE FLUID DELIVERY SYSTEM”, invented by Gibum Kim, et al., filed Dec. 18, 2008, and incorporated by reference herein.
The autosampler 204 is driven by the autosampler control module 350 for analyte delivery. The autosampler 204 is configured to receive a 96-well plate and has the option of loading up to eight individual (1.5 mL) microcentrifuge tubes. The autosampler 204 is also equipped with a wash station for needle cleansing and a sample cooling block located beneath the 96-well plate holder. The autosampler control module 350 automatically washes the sample injector with high-pressure water between injections.
The autosampler temperature control module 306 controls the samples in the well plate via a thermal electric cooler (TEC) located below the well plate. The temperature is set to a standard 4° C. A user may also disable the chiller by using an Apparatus Setup function in system control software running on the computer 302.
The system status module 334 of the electronics module 208 includes feedback such as pressure monitoring and monitoring of valve and pump handshaking with the respective drive modules. Based on signals and/or data received the system status module 334 may report status to the computer system 302, illuminate one or more status LEDs or other user interface apparatuses, modify operation of the other control modules 336, 342, and/or 350, or shut down the system 101, such as to prevent damage or an unsafe condition.
The system status module 334 may include status indicators such as LEDs located on the front panel of the SPR apparatus 101. A power indicator displays green when the system is turned on. A temperature indication is made by flashing the green power indicator while the system is warming up. The power indicator is lit solid green when the system is at operating temperature. A “system ready” indicator is illuminated solid green to indicate that the apparatus is ready to run a fluidic sequence. A flashing green “system ready” LED indicates that an experiment or fluidic recipe is in progress. A “system error” indicator does not illuminate during normal operation except for briefly flashing at start-up. The “system error” indicator flashes red if there is a parameter fault such as a wrong method, insufficient analyte, or waste level fault. The “system error” indicator is illuminated solid red if there is a system fault. System faults may include a disruption in a pump valve or overpressure in the fluidics module 210, a problem in the optics module 108 such as drive motor 312 fault or light source 308 temperature or current spike, or a communication error. Other interface portions include a Power Switch located on the back panel of the apparatus 101, 201 and a connection to the computer system 302. According to one embodiment, a video output and a universal serial bus (USB) connection are provided.
Finally, a waste level monitoring module 352 may be configured to monitor the amount of fluid received in a waste container 212 depicted in
In the flow cell module 106, the body 502 may be configured for hinged attachment 504 to a prism mounting assembly 401. As described above, the prism mounting assembly 401 may include a spill plate 404 configured to couple to a prism 320 and including at least one spill well 406. The body 502 may be configured for releasable hinged attachment 504 to a prism mounting assembly 401 and may include a body release mechanism 506 configured to release the body 502 from the prism mounting assembly 401. The flow cell mounting assembly 508 may further include a carrier release mechanism 510 configured to release the flow cell carrier 510 from the flow cell mounting assembly 508.
In the flow cell module 106, the thermoelectric heater-cooler (not shown) may be operatively coupled to an electronics module 208 of the SPR analysis apparatus 101, 201 to return at least one signal corresponding to a temperature of the flow cell 326. The thermoelectric heater-cooler (not shown) may be further configured to receive at least one signal corresponding to a command to heat or cool the fluids in the tubing (not shown) flowing to the flow cell 326 and/or to heat or cool fluids in the flow cell 326 itself.
The flow cell may be mounted in the flow cell module 106 of the SPR analysis apparatus 101, 201 by a method including coupling the flow cell 326 into a flow cell carrier 510, and coupling the flow cell carrier 510 carrying the flow cell 326 to a flow cell mounting assembly 508 of the body 502 configured to provide fluid to the flow cell 326.
Prior to mounting the flow cell 326 to the flow cell carrier 510, a top plate 520 may be assembled to a microarray 322 to form a flow cell 326 including a flow volume over the microarray 322. The assembly of the top plate 520 to the microarray 322 may be performed with a flow cell assembly jig (not shown) provided as an accessory to the SPR analysis apparatus 101, 201. The top plate 520 may be coupled to the microarray 322 using a pressure sensitive adhesive (not shown). The SPR flow cell 326 may include a substrate 522 including a microarray 322, and a top plate 520 defining a volume over the microarray 322. The top plate 520 may be joined to the substrate 522 and may include respective orifices 514, 516 for ingress and egress of fluids to and from the volume.
Conventionally, the substrate 522 of the flow cell 326 may be formed from a glass that is indexed-matched to the prism 320. According to an embodiment, the substrate 522 of the flow cell 326 may be formed substantially from a relatively low refractive index glass having a refractive index of about 1.5. In contrast, the prism 320 to which the SPR flow cell 326 may be coupled has a higher refractive index of about 1.72. The low index substrate 522 may be formed from BK-7 or Soda-Lime glass and the prism may be formed from SF-10 glass.
The substrate 522 is compatible with most microarray printers and has the dimensions 25.1 mm width, 75.4 mm length, and 1.0 mm thickness. One end of the substrate 522 has a designated area for labeling including an item number for the slide, a lot (batch) tracking number, and an area for a user to write on or affix an additional label. Each substrate is supplied with a cover slide. When stored at room temperature, the cover slides have a lifetime of over six months. When placed together, the slide and cover slide form the flow cell. The channel in the flow cell is designed to provide a fluid plug path that minimizes the effects of dispersion from one sample to the next. The flow cell 326 is described in U.S. patent application Ser. No. 11/846,883, entitled “MICROFLUIDIC APPARATUS FOR WIDE AREA MICROARRAYS”, invented by Gibum Kim, et al., filed Aug. 29, 2007; and in U.S. patent application Ser. No. 11/846,908, entitled “METHOD FOR UNIFORM ANALYTE FLUID DELIVERY TO MICROARRAYS”, invented by Gibum Kim, et al., filed Aug. 29, 2007, both of which are incorporated by reference herein.
The video and sensorgram display module 802 may receive a previously recorded sensorgram, or alternatively may generate a sensorgram from the video image. The sensorgram may be generated by monitoring changes in brightness of one or more groups of pixels during an experimental run, the one or more groups of pixels corresponding each of one or more ROIs on a microarray. An ROI selection module 804 is operable to receive user selection of ROIs within the video display, or alternatively may automatically select ROIs for display. For example, a sensorgram showing avid binding or other significant activity in an experimental run may be identified by the SPR apparatus control software application and marked, for example as tagged information in a video file, and used to select a corresponding ROI for display in the video image. A data tip module 806 may be configured to receive data from a GenePix Array List (GAL) file, an analyte information file, and/or a microarray history file; and correlate the data to provide data tip output including identification of ROIs likely to show activity. A sensorgram mapper module 808 is configured to track changes in brightness of selected ROIs to generate sensorgram data to be displayed by the sensorgram display. A spot collection hierarchy management module 810 may be configured to generate a hierarchy of spot collections, for example based on the GAL file or output from the data tip module 806. A histogram module 812 may be configured to assemble spot collection histograms for display to the user, for example in combination with the sensorgram viewer.
A manual sensorgram fitting module 814 may be provided to allow users to manually fit data to one or more of at least one kinetics models, avid binding models, and or equilibrium models. A data segmenter module 816 receives user input to define regions for fitting. For example the user may choose data segments corresponding to different analytes of interest. Alternatively, the data segmenter module 816 may provide automatic segmentation based on data trends in a sensorgram. A baseline zeroing module 818 may receive user input or automatically normalize one or more data segments by setting a baseline to a desired value such as zero. A cropping module 820 may receive user input or automatically crop a series of data to reduce the display to an area of interest. An alignment module 822 may provide time-axis alignment of multiple data series and/or time align a data series to a curve. A curve fit module 824 may allow a user to map association and/or dissociation curves to the data. For example, curve fit module 824 may provide an associate and/or dissociation curve superimposed over the data. The user may manipulate the shape of the curve by dragging and dropping portions of the curve, spline tools, or other graphical manipulation tools to provide an “eye fit” to the data. The resultant shape of the curve may be used to generate curve parameters according to a selected kinetic model. A fit protocol module 826 may save manipulations performed by the user and/or automatically by software as auto-fit protocols. The auto-fit protocols may be subsequently be replicated in software to automate manual input from the user.
An layout grid display module 828 may be configured to display sensitivity spots (e.g. GAL overlays) over a grid corresponding to the ROIs. A spot collection mapping module 830 may be configured to map the ROIs under the sensitivity spots. The modules 828 and 830 may be further configured to receive user input and/or automatically adjust the sensitivity spots to the apparent locations of the ROIs on the grid. According to embodiments, the apparent height and vertical spacing of the ROIs may change with SPR angle. The layout grid display module 828 may be configured to automatically adjust the locations of sensitivity spots responsive to angle and/or responsive to changes in the microarray image. According to an embodiment, the layout grid display module 828 includes an image processor configured to analyze the image of the microarray and compensate for distortion. According to another embodiment, the layout grid display module 828 may calculate the positions of sensitivity spots responsive to angle data received from the SPR analysis apparatus 101, 201 and/or from the SPR analysis apparatus control software application 601. This may provide dynamic changes in measurement spot placement during angle sweeping operations.
An automatic sensorgram fitting module 832 may be configured to provide automatic fitting of a sensorgram to a curve. A spot and analyte fit selection module 834 may be configured to receive user input or may be configured to automatically determine ROIs and analytes to fit (e.g., based on output from the data tip module 806). A sensorgram fit parameter selection module 836 may be configured to receive fit parameter input from a user, or alternatively may generate sensorgram fit parameters (for example from the protocols generated by the fit protocol module 826, or from correlation to a curve shape library). A sensorgram fitting module 838 may be configured to run an analysis to fit ROI brightness data to a sensorgram curve according to parameter determined by the sensorgram fit parameter module 836. For example, the sensorgram fitting module 838 may use regression analysis to provide a best fit. A fitted sensorgram display module 840 may be configured to display a sensorgram fit curve generated by the sensorgram fitting module 838 over the sensorgram data.
A kinetic analysis module 842 may be configured to analyze the fitted sensorgram curve generated by the sensorgram fitting module 838 to determine kinetics parameter values. The kinetic analysis module 842 may be configured to receive a kinetics model selection from a user. Alternatively, the kinetic analysis module 842 may automatically determine a kinetic model. For example the kinetic analysis module 842 may be configured to receive GAL and/or analyte information, and compare the GAL and/or analyte information to reference data via a global data mining module 848 (described below) to determine a reference kinetic model to use for a ligand/analyte pair. Alternatively, the kinetic analysis module 842 may be configured to compare the fitted sensorgram curve to a curve library to determine the likelihood of a given kinetic model being the correct model, and select the most likely correct model. Alternatively, the kinetic analysis module 842 may be configured to perform kinetic analysis using a plurality of kinetic models, and determine the best fit model, for example using regression analysis.
The kinetic analysis module 842 may alternatively provide a kinetic analysis based on the sensorgram data itself, rather than on a fitted sensorgram curve. The kinetic analysis module 842 may optionally and/or selectively use analysis acceleration protocols to speed the kinetic analysis. For example, the kinetic analysis module 842 may depopulate a data set corresponding to a desired parameter accuracy. For example, if a user only needs three significant digits in a parameter (and inputs that information to the fit parameter selection module 836), the kinetic analysis module 842 may remove a portion of the input data that would not change the parameter within three significant digits.
A kinetic results generator module 844 is configured to output a kinetic analysis results file including the kinetic parameters output by the kinetic analysis module 842. A kinetic table display module 846 may be configured to assemble information from the kinetic analysis results file, a GAL file, an analyte file, and/or other data sources, and output a report including the assembled data.
According to an embodiment, the SPR data analysis application 801 may include a global data mining module 848 configured to interface with the Internet. The module may optionally publish data from local experiments, e.g., a report generated by the kinetic table display module 846, and/or receive data from remote experiments.
The data analysis module software 801 may be used to display and analyze experimental data and video (.avi) files that result from conducting proteomic experiments using the SPR test apparatus 101, 201. The data analysis module may be used, for example, by chemists in laboratory environments focusing on antibody drug discovery. Such activities involve the relative ranking of affinities and investigation of the dynamics of surface plasmon resonance (SPR) binding interactions for a large number of antibody samples.
Typically, the Data Analysis Module 801 may be installed on a separate computer from the computer 302 used to run the SPR system 301. This may be recommended since users of the SPR apparatus control software 601 and the Data Analysis Module 801 may typically perform independent functions. Moreover, installation of both software applications 601, 801 on a single computer may not result in the highest productivity from the system.
The data analysis module 801 enables the precise alignment and fit of spot collections mediated by segmented analytes, and the viewing of these collections on a sensorgram. Measured over time, association and dissociation rates as well as the maximum change in intensity can be used to calculate affinity and concentrations. The data analysis module 801 may also display tabular data of relevant kinetic and binding parameters across analyte series of interest to maximize data mining opportunities. Multiple sensorgram plots of different spot collections and analyte series is provided for comparison and inclusion in reports. Because the relative affinities of thousands of target biomolecules for multiple analytes may be calculated quickly, a faster, more cost-effective, and accelerated method for the discovery of new biomolecules such as antibodies and biomarkers is provided.
The data analysis module 801 gives users the option of organizing a collection of spots in the microarray 322 using hierarchical classes. A user may define a plurality, for example up to four, arbitrary classifications of spots within a microarray 322. A given spot may be a member of a set, family, group, and series. The hierarchy 901 is organized with subsets as illustrated in
A spot set 902 is a collection of spots that are closely related in a user-defined way. For example, the spot set 902 may be likely to be plotted together for analysis at the end of an experiment. For example, several spots of the same protein, printed at different concentrations, may comprise a set 902. Alternatively, a set 902 may be a collection of peptides that are similar, for example having single amino acid substitutions at a particular amino acid in the sequence. The spots that make up a set 902 do not have to be located contiguously on the microarray 322, and may be located anywhere within the printable area.
Spots may be organized further as families 904 that are members of a set 902. Families 904 are also collections of spots that are closely related in another user-defined way. A set 902 may be made up of zero, one, or many families 904. In turn, a family 904 may be comprised of zero, one, or many groups 906, and each group 906 may be comprised of zero, one, or many series 908. The spots that make up a family 904, group 906, or series 908 do not have to be located contiguously on the microarray 322 and may, for example, be located anywhere within the printable area.
According to an example, a researcher has a library of antibodies she wants to array. To track how the proteins are spotted and facilitate the data analysis, the researcher may categorize the collection based on the nature of the antibodies and how they are treated experimentally. For example, the array could be organized as follows:
Alternatively, another researcher may choose to organize a microarray 322 based on how the samples were expressed, purified, prepared for spotting (e.g., types of buffers), printed (e.g., printer settings), etc.
Another feature available from all tabs is a menu bar 1014. Menus may, for example, allow access to data files to be analyzed, data analysis options, video file or source selection, and help files. Video controls 1016 are used to control video file playback. The SPR analysis software application 701, 801 may be used separate from data collection. This separation may reflect the way experiments are typically run where data may be collected at one time and/or location, and the collected data subsequently analyzed at a different time and/or location. Alternatively, the data analysis software application 701, 801 may be run in real time with data collection. For real time applications at least some of the video controls 1016 may be replaced or augmented by SPR apparatus 101, 201 controls.
For separate operation, referring to
Referring to
Typically, a GenePix Array List (GAL) file may be loaded to provide definition for spots or regions of interest (ROI) that are on a given microarray. The GAL file is a text file that is generated by a microarray printer, the text file specifying the location, size, and name of each protein spot on the array. The header of each GAL file contains structural and positional information. Data records in each GAL file contain name and detailed identifier information from each spot. A GAL file may be selected, for example, from the file menu in the menu bar 1014. When a GAL file is selected, the spot collection directory 1008 and/or the selected for analysis list 1010 may be automatically populated. The GAL file may be loaded by accessing a File >Open command on the menu bar 1014, or optionally by selecting a “Load GAL File” button on a video setup screen shown below. Loading a GAL file is optional.
Proceeding to Step 1106, the microarray spots may be aligned to analysis software sensitivity regions. Optionally, the GAL file may be used to calibrate the image.
The microarray spots are aligned by adjusting the image position buttons 1204, 1206, 1208, and 1210 arranged around the microarray video image 1202. This is done to align GAL overlays over the ROIs. The GAL overlays indicate the pixels or areas in the video image 1202 that will be used to track changes in surface plasmon resonance, the changes being expressed as changes in apparent reflectivity and, as described above, corresponding to an amount of analyte bound to a ligand printed on a given ROI. Adjusting the image position buttons 1204, 1206, 1208 and 1210 moves the GAL overlays relative to the microarray video image 1202. Generally, it is advisable to adjust the GAL overlays to be positioned near the center of each corresponding spot on the microarray. Adjustment of the GAL overlays may be used to drive an update of the GAL file to improve the accuracy of ROI position information included in the GAL file. This may be done dynamically, automatically, or responsive to a user selecting an “Apply GAL Calibration” button in a group of GAL alignment buttons 1212. Optionally, GAL overlays may be adjusted numerically using GAL overlay values in GAL overlay numeric input fields 1214. The numeric input fields 1214 may be expressed as pixel values.
Optionally, the data analysis software application 701, 801 may include image processing software configured to optimize the alignment between the ROIs and corresponding GAL overlays. Optionally, the data analysis software application 701, 801 may use angle θ and θ′ information in the GAL file to automatically align or partially align the GAL overlays to the ROIs.
For embodiments where a GAL file is not provided, for example, GAL overlays may be generated and a GAL file generated. To generate GAL overlays, or where existing GAL overlays are not very accurate to start with, the user may select buttons “Alight Top/Left Spot” and “Align Bottom/Right” in the GAL alignment buttons 1212. Intermediate GAL overlays may then be generated between the top left and bottom right ROIs in the image. A Reset button 1216 cancels GAL overlay alignment performed in the current session and restores starting positions of the GAL overlays.
Referring again to
During spot selection, a selected spot may be highlighted and its identifying data given, as shown by spot 1302 in
Referring again to
Referring again to
Referring again to
The measurement details sub-tab 1502 includes a dialog box that includes a cartoon of the measurement area 1512 of selected ROI on the microarray and its satellites 1514. Using the Intensity Sensor Configuration tools in the dialog box 1502, the user may configure an ROI and its satellites. Such adjustment may be made by dragging and dropping the measurement indicators and/or by entering data in data entry boxes 1516. The ROI and satellite configuration may made to individual ROIs and/or may be applied to all ROIs via the “Apply Configuration Globally” button 1518. Parameters that may be customized with the measurement details tools include spot and satellite locations, spot and satellite sizes, and spot and satellite shapes. One or more spots and/or satellites may also be selected to be hidden (e.g., ignored). For example, if the microarray has a smear or a satellite or spot is in the path of a bubble, the data may be ignored to reduce any aliasing in the data.
Satellites are used for background subtraction. Background subtraction may be valuable to account for differences in image intensity that are not due to binding. The satellite measurements are generally taken in regions corresponding to a non-specific binding (NSB) resistant background surrounding the printed analyte. For example, if a sample containing an analyte is injected at a temperature different than the buffer solution, or if the bulk index of refraction of the sample is otherwise different than the buffer solution, then the SPR intensity may change substantially uniformly as the sample flows over the microarray. Such uniform changes may be observed in an unconfounded way by observing the response of the satellites. If the fluid contains an analyte that an ROI is selected to bind, then the intensity of the ROI will be affected both by the analyte binding and by the bulk change in refractive index. The SPR analysis software 701, 801 is configured to subtract changes in response of the satellites from the response of the ROI. This subtraction thus compensates for changes in SPR response not related to analyte binding.
As an alternative to manual editing of spots and satellites, the SPR analysis software 701, 801 may include an image analysis software module and/or other modules that automatically configure the measurement spot and its satellites, for example using considerations disclosed above.
Returning to
Optionally, a kinetics modeling module may include automatic kinetics model selection and be configured to select a kinetics model to best fit SPR data. For example one or more sets of SPR data may be fit to each of a plurality of kinetics models. The fitting to a plurality of kinetics models may, for example, be computed using a corresponding plurality of regression analyses. The kinetics model providing the best fit to the data, optionally including one or more additional constraints, may then be nominated as the proper kinetics model. Additional curve-fitting and regression analysis of corresponding to additional experimental runs of the association and dissociation reactions may be used to prove or disprove the nominated kinetics model. Alternatively, the nominated kinetics model may be accepted as the proper kinetics model without additional experimental data.
Proceeding to step 1120, a video analysis may be run. Returning to
The “reference subtracted” window 1506 shows the association and dissociation curves with the satellite values subtracted from the spot value. The scale is also expanded because the reference subtraction removed the steep increase in reflectivity at the beginning of the run corresponding to system start-up (and light source warm-up). The scale of both plot windows is selected automatically by a plotting module of the software to maximize sensitivity while keeping the curves within range. The dissociation of the analyte is somewhat easier to see in the “reference subtracted” window 1506. The two association/dissociation curves result in different responses because the analyte was at a higher concentration in the second injection.
Returning to
Returning to
Generally, the SPR data analysis program described herein provides a graphical user interface to a plurality of software modules configured to receive SPR data from an SPR analysis apparatus 101, 201 and generate kinetics modeling, ad-hoc experimental output, screening for avid binders, and/or other functions. Optionally, one or more of the above-described functions may be run automatically and substantially without user intervention. Accordingly, the user-initiated or user-mediated steps described above also describe software-initiated or software-mediated steps.
Within the apparatus setup dialog box 1701, a degasser control 1740 may be used to turn the fluidics module degasser on or off. A flow cell temperature control 1728 may be selected to turn flow cell temperature control on or off. A flow cell temperature set point control 1730 may be adjusted to a desired flow cell temperature, and a flow cell temperature indicator 1732 is configured to display the actual temperature of the flow cell or tubing leading to the flow cell. Similarly a well plate temperature control 1734, well plate temperature set point control 1736 and well plate temperature indicator 1738 indicates the actual temperature of the autosampler well plate.
“Next” and “back” buttons 1742 may be used by a user to be automatically guided through the setup and/or apparatus run process, according to an embodiment. Pressing the “next” button advances the screen to the next screen where interaction with the apparatus control application 601 is indicated in the workflow flowchart of
Referring again to
Proceeding to steps 1612 and 1614, the user accesses the fluid supply volume 104 and checks the reagent bottles 206 (visible in
Proceeding to step 1620, the user may build experiment recipes and determine what samples to load into the SPR analysis apparatus 101, 102.
For example, referring to step 1626 of
According to an example, “location” identifies a decimal bottle number containing a reagent. “Name” is a free-form alphanumeric description of the reagent. “Concentration” is a concentration of the reagent. “Association flow rate” is the flow rate of the fluid in a microliters/second decimal value at which the reagent is pumped through the flow cell during an association phase. “Association duration” is the length of time in decimal seconds during which the reagent is pumped through the flow cell during the association phase. “Dissociation flow rate” is the flow rate of the fluid in a microliters/second decimal value at which the reagent is pumped through the flow cell during a dissociation phase. “Dissociation duration” is the length of time in decimal seconds during which the reagent is pumped through the flow cell during the dissociation phase. “Date” is the date the reagent was put in the reagent bottle. In step 1628 the user may navigate to the next screen by pressing the next button 1742, or the user may alternatively navigate using other controls. Proceeding to step 1630, the user prepares and loads analyte fluids, for example by loading an autosampler 204 well plate or by loading individual samples into a sample holder. The samples loaded correspond to the analyte data entered in the analyte table in step 1624.
Proceeding to step 1638 of
The “prime system” button 1912 is selected in step 1640. Responsive to receiving a prime system command, a prime module the apparatus control software 601 commands one or more of the pumps in the fluidics module 210 to fill tubing to the flow cell 326 and the flow cell 326 itself and flush the tubing and flow cell 326 with running buffer solution. Proceeding to step 1642, the user navigates to the “load and prime analytes” screen by selecting the sub-tab “load analytes” 1914 to reach a screen that looks similar to screen 1901 of
The process of
Similarly, according to embodiments, instructions such as graphical instructions, written instructions, and/or video instructions may be provided on other apparatus control software 601 screens. The SPR apparatus control software 601 may thus provide self-contained training for use of the SPR analysis apparatus 101, 201 to a novice or experienced user.
Proceeding to step 1656, the user may accept default values or may enter flow rate and duration in the flow rate and duration controls 2006.
Proceeding to step 1664 of
The user sets the SPR angle sweep by entering the end position (in millimeters) 2112 for the optics angle and movement increment (in tenths of a millimeter) 2113. A smaller increment may provide greater accuracy. The user then clicks the start button 2116. The optics position will move from 0 to the end position 2113, followed by a brightening of the image region 2107.
Proceeding to step 1666, the user may select the SPR curves & parking angle tab 2104.
Proceeding to step 1672, the user accesses the assign ROI screen 2301, shown in
Proceeding to steps 1676 and 1678, the user is ready to run an experiment.
Proceeding to step 1682, if a user sees a problem with a run, the user may press the interrupt process to stop the experimental run. The user may repeat any and/or all of the steps 1602 through 1680.
Proceeding to step 1686, if there is no abort or interrupt command received by the SPR apparatus control program 601, a run module of the program 601 sequences through a series of commands to the SPR analysis apparatus 101, 201 configured to drive a sequence of pump and valve actuations in the fluidics module to run the reagents and analytes defined in the method setup screen 1801 of
Proceeding to steps 1690, 1691, 1692, and 1693, and in reference to
Those skilled in the art will appreciate that the foregoing specific exemplary processes and/or devices and/or technologies are representative of more general processes and/or devices and/or technologies taught elsewhere herein, such as in the claims filed herewith and/or elsewhere in the present application.
While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
This application claims priority benefit under 35 U.S.C. § 119(e) from, and to the extent not inconsistent with this application, incorporates by reference herein U.S. Provisional Patent Application Ser. No. 61/072,333; filed Mar. 27, 2008; entitled “SURFACE PLASMON RESONANCE SYSTEM AND APPARATUS FOR INTERROGATING A MICROARRAY”; invented by Paul Boeschoten, R. Todd Schwoerer, Michael Cicirelli, Timothy Londergan, Christopher A. Wiklof, Sunny Zhang, Frank Metting, Keith Hoffman, Shuxin Cong, Larry Gill, Markus Tarin, John Cabrer, Gibum Kim, Christina Boozer, and Pietro Brandani. This application is related to U.S. patent application Ser. No. TBD (attorney docket number 2648-023-03); filed the same day as this application; entitled “USER INTERFACE AND METHOD FOR USING AN SPR SYSTEM”; invented by Paul Boeschoten, Christina Boozer, Pietro Brandani, John Cabrer, Michael Cicirelli, Shuxin Cong, Larry Gill, Keith Hoffman, Gibum Kim, Timothy Londergan, Frank Metting, R. Todd Schwoerer, Markus Tarin, Christopher A. Wiklof, and Sunny Zhang.
Number | Date | Country | |
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61072333 | Mar 2008 | US |