Digital lspr for enhanced assay sensitivity

Abstract

Systems, methods, and devices related to detecting a presence of an analyte and/or determining a concentration of analytes are provided. An analyte may be provided on an LSPR-active surface. The LSPR-active surface may comprise sensitivity enhancing labels. The analyte may induce a local change near the LSPR-active surface. The LSPR-active surface may be imaged with an imaging device for images before, during, or after a reaction takes place. Local regions of interest within the images may be analyzed to detect the local changes.

What is claimed is: 
     
         1 . A method for detecting an analyte in a sample, comprising:
 capturing a series of two or more images of a sensor surface, wherein the sensor surface is capable of sustaining a localized surface plasmon resonance;   selecting one or more corresponding regions of interest in the series of two or more images;   measuring a change in color within the selected regions of interest over the series of two or more images; and   detecting an analyte based on the measured change in color.   
     
     
         2 . The method of  claim 1 , wherein a limit of detection for detecting the analyte is better than 1 ng/mL. 
     
     
         3 . The method of  claim 1 , wherein a limit of detection for detecting the analyte is better than 1 pg/mL. 
     
     
         4 . The method of  claim 1 , wherein a limit of detection for detecting the analyte is better than 1 fg/mL. 
     
     
         5 . The method of  claim 1 , further comprising determining a concentration of the analyte based on the measured change in color. 
     
     
         6 . The method of  claim 1 , wherein the change in color is a change in RGB value of pixels in the corresponding regions of interest. 
     
     
         7 . The method of  claim 1 , wherein the measured change in color is a change in color of light reflected from the sensor surface. 
     
     
         8 . The method of  claim 1 , wherein each of the selected regions of interest is an area of the sensor surface of about or less than 5 um 2 . 
     
     
         9 . The method of  claim 1 , wherein each of the selected regions of interest is a grid of 3×3 pixels. 
     
     
         10 . The method of  claim 1 , wherein the series of two or more images are captured before and after the local analyte-induced change occurs. 
     
     
         11 . The method of  claim 1 , wherein the analyte is selected from the group consisting of a peptide, a protein, an oligonucleotide, a DNA molecule, an RNA molecule, a virus, a bacterium, a cell, a lipid molecule, a carbohydrate molecule, a small organic molecule, a drug molecule, or an ion. 
     
     
         12 . The method of  claim 1 , wherein the sensor surface is contacted with a primary binding component, the analyte, and a secondary binding component sequentially or simultaneously, wherein the secondary binding component is a sensitivity enhancing label. 
     
     
         13 . The method of  claim 12 , wherein the sensitivity enhancing label is an enzyme that catalyzes a conversion of a reactant to an insoluble product, thereby forming a precipitate on the sensor surface. 
     
     
         14 . The method of  claim 13 , wherein the sensitivity enhancing label catalyzes a reaction that results in a deposition of a polymer, a biopolymer, a chemical compound, or an enzymatic reaction product selected from a group consisting of inorganic compounds, organic compounds, chemiluminescent compounds, and fluorescent compounds. 
     
     
         15 . The method of  claim 12 , wherein the sensitivity enhancing label is a metallic nanoparticle that is capable of inducing plasmon-plasmon coupling between the metallic nanoparticle and the sensor surface. 
     
     
         16 . The method of  claim 1 , wherein the one or more corresponding regions of interest is randomly selected. 
     
     
         17 . The method of  claim 16 , wherein a plurality of corresponding regions of interest is selected. 
     
     
         18 . The method of  claim 17 , wherein the plurality of corresponding regions of interest is 10 or more corresponding regions of interest. 
     
     
         19 . The method of  claim 17 , wherein the plurality of corresponding regions of interest is 100 or more corresponding regions of interest. 
     
     
         20 . The method of  claim 1 , wherein an integration time required for capturing the series of two or more images is less than 50 ms. 
     
     
         21 . The method of  claim 1 , wherein the analyte is present in the sample in an amount of 100 ng/mL or less. 
     
     
         22 . The method of  claim 1 , wherein the analyte is present in the sample in an amount of 1 ng/mL or less. 
     
     
         23 . The method of  claim 1 , wherein the analyte is present in the sample in an amount of 1 pg/mL or less. 
     
     
         24 . The method of  claim 1 ,  13 ,  15 , or  21  further comprising receiving a report comprising a result of the method and making a healthcare decision based on the reported result, wherein the sample is a patient sample. 
     
     
         25 . A system for detecting an analyte in a sample, the system comprising:
 a sensor surface, wherein the sensor surface is capable of sustaining a localized surface plasmon resonance;   an optical imaging device, wherein the optical imaging device is capable of capturing a series of two or more images; and   a processor, wherein the processor is capable of selecting one or more corresponding regions of interest in the series of two or more images, measuring a change in color within the selected regions of interest, and detecting an analyte based on the measured change in color.   
     
     
         26 . The system of  claim 25 , wherein a limit of detection for detecting the analyte is better than 1 ng/mL. 
     
     
         27 . The system of  claim 25 , wherein a limit of detection for detecting the analyte is better than 1 pg/mL. 
     
     
         28 . The system of  claim 25 , wherein a limit of detection for detecting the analyte is better than 1 fg/mL. 
     
     
         29 . The system of  claim 25 , wherein the processor is capable of determining a concentration of the analyte based on the measured change in color. 
     
     
         30 . The system of  claim 25 , wherein the change in color is a change in RGB value of pixels in the corresponding regions of interest. 
     
     
         31 . The system of  claim 25 , wherein the sensor surface is opaque and reflects light. 
     
     
         32 . The system of  claim 25 , wherein each of the corresponding regions of interest is an area of the sensor surface of about or less than 5 um 2 . 
     
     
         33 . The system of  claim 25 , wherein each of the corresponding regions of interest is a grid of 3×3 pixels. 
     
     
         34 . The system of  claim 25 , wherein the series of two or more images are captured before and after the change in color. 
     
     
         35 . The system of  claim 25 , wherein the analyte is selected from the group consisting of a peptide, a protein, an oligonucleotide, a DNA molecule, an RNA molecule, a virus, a bacterium, a cell, a lipid molecule, a carbohydrate molecule, a small organic molecule, a drug molecule, or an ion. 
     
     
         36 . The system of  claim 25 , further comprising a fluidic system for delivery of a sample and assay reagents to the sensor surface, wherein the assay reagents comprise a primary binding component and a secondary binding component, and wherein the secondary binding component comprises a sensitivity enhancing label. 
     
     
         37 . The system of  claim 36 , wherein the sensitivity enhancing label is an enzyme that catalyzes a conversion of a reactant to an insoluble product, thereby forming a precipitate on the sensor surface. 
     
     
         38 . The system of  claim 37 , wherein the enzyme catalyzes a reaction that results in a deposition of a polymer, a biopolymer, a chemical compound, or an enzymatic reaction product selected from a group consisting of inorganic compounds, organic compounds, chemiluminescent compounds, and fluorescent compounds. 
     
     
         39 . The system of  claim 36 , wherein the sensitivity enhancing label is a metallic nanoparticle that is capable of inducing plasmon-plasmon coupling between the metallic nanoparticle and the sensor surface. 
     
     
         40 . The system of  claim 25 , wherein the processor is capable of randomly selecting one or more corresponding regions of interest in the series of two or more images. 
     
     
         41 . The system of  claim 40 , wherein the processor is capable of selecting a plurality of corresponding regions of interest. 
     
     
         42 . The system of  claim 41 , wherein the plurality of corresponding regions of interest is 10 or more corresponding regions of interest. 
     
     
         43 . The system of  claim 41 , wherein the plurality of corresponding regions of interest is 100 or more corresponding regions of interest. 
     
     
         44 . The system of  claim 25 , wherein an integration time of the optical imaging device is less than 50 ms. 
     
     
         45 . The system of  claim 25 , wherein the analyte is present in the sample in an amount of 100 ng/mL or less. 
     
     
         46 . The system of  claim 25 , wherein the analyte is present in the sample in an amount of 1 ng/mL or less. 
     
     
         47 . The system of  claim 25 , wherein the analyte is present in the sample in an amount of 1 pg/mL or less. 
     
     
         48 . The system of  claim 25 ,  37 ,  39 , or  45 , wherein the sample comprises a patient sample and the detection of the analyte is used for clinical diagnostic applications. 
     
     
         49 . A computer readable medium including code for causing a computer to execute a method comprising:
 selecting one or more corresponding regions of interest, in each of a series of two or more images of a sensor surface, wherein the sensor surface is capable of sustaining a localized surface plasmon resonance;   measuring a change in color by comparing the color for corresponding regions of interest in the series of two or more images; and   determining presence of an analyte based on the measured change in color.   
     
     
         50 . The computer readable medium of  claim 49 , wherein the one or more corresponding regions of interest is randomly selected. 
     
     
         51 . The computer readable medium of  claim 50 , wherein a plurality of regions of interest is selected. 
     
     
         52 . The computer readable medium of  claim 49 , wherein the change in color is a change in RGB value of pixels within the corresponding region of interest. 
     
     
         53 . The computer readable medium of  claim 52 , wherein the change in RGB value is measured according to the formula D=√{square root over ((ΔR) 2 +(ΔG) 2  (ΔB) 2 )}{square root over ((ΔR) 2 +(ΔG) 2  (ΔB) 2 )}{square root over ((ΔR) 2 +(ΔG) 2  (ΔB) 2 )} wherein ΔR, ΔG, and ΔB correspond to changes in red, green and blue pixel values in an image. 
     
     
         54 . The computer readable medium of  claim 49  further comprising calculating a moment for the distribution of changes in RGB or greyscale values. 
     
     
         55 . The computer readable medium of  claim 49 , further comprising using pattern mining algorithms to delineate areas of the sensor surface that exhibit different responses to contact by the analyte.