Graphene-based nanosensor for identifying target analytes

Abstract

A microdevice for monitoring a target analyte is provided. The microdevice can include a field effect transistor comprising a substrate, a gate electrode, and a microfluidic channel including graphene. The microfluidic channel can be formed between drain electrodes and source electrodes on the substrate. The microdevice can also include at least one aptamer functionalized on a surface of the graphene. The at least one aptamer can be adapted for binding to the target analyte. Binding of the target analyte to the at least one aptamer can alter the conductance of the graphene.

1 . A microdevice for monitoring a target analyte, the microdevice comprising:
 a field effect transistor comprising:
 a substrate; 
 a gate electrode; and 
 a microfluidic channel including graphene, wherein the microfluidic channel is formed between drain electrodes and source electrodes on the substrate; and 
   at least one aptamer functionalized on a surface of the graphene, wherein the at least one aptamer is adapted for binding to the target analyte, and wherein binding of the target analyte to the at least one aptamer can alter the conductance of the graphene.   
     
     
         2 . The microdevice of  claim 1 , wherein the microfluidic channel is bound to the substrate for analyte and buffer introduction to initiate association and dissociation of the target analyte to the at least one aptamer. 
     
     
         3 . The microdevice of  claim 1 , wherein the field effect transistor further comprises a gate capacitor comprising of an electrical double layer formed at the interface of the graphene and the solution. 
     
     
         4 . The microdevice of  claim 1 , wherein binding of the target analyte to the at least one aptamer causes a conformational change of the at least one aptamer, causing the target analyte to be brought into a proximity to the surface of the graphene. 
     
     
         5 . The microdevice of  claim 4 , wherein the target analyte being brought into proximity to the surface of the graphene causes electrical properties of graphene to change by at least one of charge transfer and electrostatic interaction. 
     
     
         6 . The microdevice of  claim 1 , further comprising at least one of an on-chip temperature sensor and a Peltier module to perform closed-looped temperature control of the microdevice. 
     
     
         7 . The microdevice of  claim 1 , wherein the microdevice is configured to provide a label-free direct characterization of biomolecular binding properties with one-step electrical readout. 
     
     
         8 . The microdevice of  claim 1 , wherein binding of the target analyte to the aptamer causes a carrier concentration in the graphene to be altered, resulting in a detectable signal. 
     
     
         9 . The microdevice of  claim 1 , wherein the at least one aptamer is functionalized on the surface of the graphene using a linker, wherein the linker is configured to be irreversibly attached to the graphene without altering electronic properties of the graphene. 
     
     
         10 . The microdevice of  claim 9 , wherein the at least one aptamer is directly attached to the linker by forming an amide bond. 
     
     
         11 . The microdevice of  claim 9 , wherein the linker can be coupled to the graphene via stacking, and wherein the at least one aptamer can be attached to the free end of linker by forming an amide bond. 
     
     
         12 . The microdevice of  claim 9 , wherein the linker comprises 1-pyrenebutanoic acid succinimidyl ester (PASE). 
     
     
         13 . The microdevice of  claim 1 , wherein the field effect transistor further comprises a source electrode and a drain electrode, and wherein the graphene makes contact with both the source electrode and the drain electrode. 
     
     
         14 . The microdevice of  claim 1 , wherein the graphene comprises a single layer sheet. 
     
     
         15 . The microdevice of  claim 1 , wherein the target analyte is disassociated from the at least one aptamer by introducing a buffer to the at least one aptamer. 
     
     
         16 . A method for monitoring a target analyte using an aptamer capable of binding to a target analyte, comprising:
 placing a nanosensor in contact with target analytes, wherein the nanosensor comprises a first conductance element functionalized with an aptamer configured to detect the target analyte and a second conductance element that is insensitive to the target analyte;   detecting a difference, if any, in the conductance of the first and second conductance elements; and   based on the detected difference, determining a presence of the target analyte.   
     
     
         17 . The method of  claim 16 , wherein the binding of the aptamer with the target analyte causes a change in the charge density on the first conductive element surface. 
     
     
         18 . The method of  claim 16 , wherein a differential measurement of the conductance of the first conductance element and the second conductive element provides for determination of the presence of the target analyte and reduces an environmental factor. 
     
     
         19 . The method of  claim 16 , wherein a surface of the first conductance element is adapted for a change in charge density thereon upon the binding of the aptamer with the target analyte. 
     
     
         20 . The method of  claim 16 , wherein the nanosensor is adapted for real-time detection of a target analyte concentration. 
     
     
         21 . The method of  claim 16 , wherein the real-time detection is continuous over time. 
     
     
         22 . The method of  claim 20 , wherein the target analyte concentration is a physiologically relevant concentration. 
     
     
         23 . The method of  claim 16 , further modifying the aptamer to adjust a specificity of the nanosensor to the target analyte. 
     
     
         24 . The method of  claim 23 , wherein the target analyte includes an insulin. 
     
     
         25 . The microdevice of  claim 1 , wherein a specificity of the microdevice to the target analyte is adjusted by modifying the aptamer. 
     
     
         26 . The microdevice of  claim 4 , wherein the conformational change of the at least one aptamer includes parallel G-quadruplex conformation and antiparallel G-quadruplex conformation. 
     
     
         27 . The microdevice of  claim 1 , wherein the at least one aptamer is a guanine-rich IGA3 aptamer. 
     
     
         28 . The microdevice of  claim 12 , wherein the aptamer is coupled to the PASE through a reaction of an amino group of the aptamer with N-hydroxysuccinimide ester of PASE. 
     
     
         29 . The microdevice of  claim 1 , wherein the microdevice is adapted for real-time detection of changes in the target concentration. 
     
     
         30 . The microdevice of  claim 29 , wherein the real-time detection is continuous over time.