Portable and Cartridge-Based Surface Plasmon Resonance Sensing Systems

Abstract

This specification discloses various improvements in the field of SPR sensing systems. One improvement relates to a portable SPR sensing system, e.g., a system contained within a suitcase that can be hand-carried to a monitoring site. Another improvement relates to a portable, cartridge-based SPR sensing system. In this system, selected portions of the system's electrical and fluidics systems are allocated between a base unit and a removable/disposable cartridge. Other improvements relate to methods or protocols for operating an SPR sensing system. Such methods provide for the elimination of false positives and increased sensitivity, e.g., by using secondary antibodies with specificity for different target epitopes and by sensor element redundancy. In addition, protocols are provided for the detection of small molecules. Such protocols may employ a competition type assay where the presence of the analyte inhibits the binding of antibodies to surface immobilized analyte, or a displacement assay, where antibodies bound to the analyte on the sensor surface are displaced by free analyte.

1 . A portable surface plasmon resonance (SPR) sensing system, comprising:
 a portable housing;   sensing means for detecting the presence of predefined agents in a fluid medium using SPR, wherein at least a portion of said sensing means is contained within said portable housing.   
     
     
         2 . A system as recited in  claim 1 , wherein said predefined agents comprise biological agents. 
     
     
         3 . A system as recited in  claim 1 , wherein said predefined agents comprise chemical agents. 
     
     
         4 . A system as recited in  claim 1 , wherein said sensing means comprises an electrical system and a fluidics system. 
     
     
         5 . A system as recited in  claim 4 , wherein said electrical system comprises at least one SPR sensor, an air pump for pressurizing said fluidics system, and a peristaltic pump. 
     
     
         6 . A system as recited in  claim 4 , wherein said fluidics system comprises an injection port; a first valve in fluid communication with the injection port; a pressurized buffer reservoir; a sample loop in fluid communication with the buffer reservoir; a flowcell in fluid communication with said sample loop; a second valve in fluid communication with said flowcell; and a waste reservoir in fluid communication with said second valve. 
     
     
         7 . A system as recited in  claim 6 , further comprising a degasser in fluid communication with the sample loop. 
     
     
         8 . A system as recited in  claim 4 :
 wherein said electrical system comprises at least one SPR sensor, a digital signal processor (DSP), a temperature controller, an air pump, and a peristaltic pump;   wherein said fluidics system comprises an injection port; a first valve in fluid communication with the injection port; a pressurized buffer reservoir; a sample loop in fluid communication with the buffer reservoir; a flowcell in fluid communication with said sample loop; a second valve in fluid communication with said flowcell; and a waste reservoir in fluid communication with said second valve; and   wherein said peristaltic pump is situated between said flowcell and said waste reservoir; said air pump is arranged so as to pressurize said buffer; and said SPR sensor is coupled to said flowcell so as to place a sample fluid in said flowcell in contact with said SPR sensor.   
     
     
         9 . A system as recited in  claim 8 , further comprising a degasser in fluid communication with said sample loop and said flowcell, said degasser comprising a gas-permeable hydrophobic hollow fiber, wherein bubbles and dissolved gases are able to exit through pores in walls of the hollow fiber; and pressure sensors disposed at opposite ends of said hollow fiber. 
     
     
         10 . A system as recited in  claim 8 , further comprising a concentrator in fluid communication with said sample loop and said flow cell. 
     
     
         11 . A system as recited in  claim 8 , wherein said fluidics system further comprises a third valve in fluid communication with said sample loop. 
     
     
         12 . A system as recited in  claim 8 , wherein said electrical system further comprises a digital signal processor (DSP). 
     
     
         13 . A system as recited in  claim 8 , wherein said electrical system comprises a plurality of multi-channel SPR sensors. 
     
     
         14 . A system as recited in  claim 1 , wherein said system comprises a disposable cartridge constructed to be removably inserted into said housing, said cartridge containing portions of said sensing means. 
     
     
         15 . A system as recited in  claim 14 , wherein said sensing means comprises: a base unit electrical system and a base unit fluidics system contained within said base unit housing; and a cartridge electrical system and a cartridge fluidics system contained within said disposable cartridge; and wherein said disposable cartridge comprises a thermally insulating plastic casing; a sample injection port coupled to said cartridge housing; a plurality of SPR sensors contained within said casing; and at least one battery contained within said casing, said at least one battery providing power for electrical components contained in the cartridge and the base unit housing when the cartridge is mated with the base unit. 
     
     
         16 . A system as recited in  claim 6 , wherein said first and second valves are electronically-controllable zero dead-volume valves. 
     
     
         17 . A system as recited in  claim 8 , wherein said first and second valves are electronically-controllable zero dead-volume valves. 
     
     
         18 . A system as recited in  claim 6 , wherein a flow channel leading to said flow cell is characterized by a volume that is designed in accordance with the flow rate to provide a desired time in which a sample fluid reaches said flow cell 
     
     
         19 . A system as recited in  claim 8 , wherein a flow channel leading to said flow cell is characterized by a volume that is designed in accordance with the flow rate to provide a desired time in which a sample fluid reaches said flow cell. 
     
     
         20 . A system as recited in  claim 1 , wherein said sensing means comprises an electrical system and a fluidics system;
 said electrical system comprising a plurality of multi-channel SPR sensors, an air pump for pressurizing said fluidics system, a peristaltic pump, and a temperature control system;   said fluidics system comprising an injection port; a first zero dead-volume valve in fluid communication with the injection port; a pressurized buffer reservoir; a sample loop in fluid communication with the buffer reservoir; a flowcell in fluid communication with said sample loop; a second zero dead-volume valve in fluid communication with said flowcell; a waste reservoir in fluid communication with said second valve; and a degasser in fluid communication with the sample loop; and   wherein said peristaltic pump is situated between said flowcell and said waste reservoir, and said SPR sensors are coupled to said flowcell so as to place a sample fluid in said flowcell in contact with said SPR sensors.