Surface-modified single-walled carbon nanotubes and methods of detecting a chemical compound using same

Abstract

A method for surface modification of single walled carbon nanotubes. In one embodiment, the method includes the steps of providing a detergent solution, adding a plurality of single walled carbon nanotubes into the detergent solution, performing a first sonication to disperse the single walled carbon nanotubes in the detergent solution, and performing a second sonication after the first sonication to make detergent encased single walled carbon nanotubes. At least one of the plurality of single walled carbon nanotubes is at least partially wrapped by one or more detergent molecules to make it a detergent encased single walled carbon nanotube. In one embodiment, the detergent comprises SDS, PSS or a combination of them.

1 . A method for surface modification of single walled carbon nanotubes, comprising the steps of: 
 a. providing a detergent solution;    b. adding a plurality of single walled carbon nanotubes into the detergent solution;    c. performing a first sonication to disperse the single walled carbon nanotubes in the detergent solution; and    d. performing a second sonication after the first sonication to make detergent encased single walled carbon nanotubes,    wherein at least one of the plurality of single walled carbon nanotubes is at least partially wrapped by one or more detergent molecules to make it a detergent encased single walled carbon nanotube.    
     
     
         2 . The method of  claim 1 , wherein the detergent comprises SDS, PSS or a combination of them.  
     
     
         3 . The method of  claim 1 , wherein the first sonication process is performed at a frequency in the range of from 0 to 20 kHz for a time period of from 0 to 5 minutes.  
     
     
         4 . The method of  claim 1 , wherein the second sonication process is performed at a frequency in the range of from 20 to 200 kHz for a time period of from 0 to 15 minutes.  
     
     
         5 . The method of  claim 1 , wherein each of the first and second sonication processes is performed at a frequency for a time period such that no significant amount of defects that may affect the optical properties of the single walled carbon nanotubes is introduced.  
     
     
         6 . The method of  claim 1 , wherein at least one optical property of the detergent encased single walled carbon nanotubes responds to a chemical property change in the solution of the detergent encased single walled carbon nanotubes.  
     
     
         7 . The method of  claim 6 , wherein the single walled carbon nanotubes comprise semiconducting nanotubes, metallic nanotubes or a combination of them.  
     
     
         8 . The method of  claim 7 , wherein the response of the at least one optical property of the detergent encased single walled carbon nanotubes to the chemical property change of the solution of the detergent encased single walled carbon nanotubes is more sensitively related to the semiconducting nanotubes than the metallic nanotubes in the solution of the detergent encased single walled carbon nanotubes.  
     
     
         9 . The method of  claim 6 , wherein the response of the at least one optical property of the detergent encased single walled carbon nanotubes to the chemical property change of the solution of the detergent encased single walled carbon nanotubes is reversible.  
     
     
         10 . A biosensor responsive to a chemical property in an environment, comprising: 
 a. a plurality of single walled carbon nanotubes forming an array and showing a dependence of the chemical property, wherein at least one of the plurality of single walled carbon nanotubes is at least partially wrapped by one or more detergent molecules to make it a detergent encased single walled carbon nanotube; and    b. a processor coupled to the array of the plurality of single walled carbon nanotubes for processing the response of the plurality of single walled carbon nanotubes to the chemical property.    
     
     
         11 . The biosensor of  claim 10 , wherein the detergent comprises SDS, PSS or a combination of them.  
     
     
         12 . The biosensor of  claim 10 , wherein the chemical property is a hydrogen peroxide concentration in an environment, and the detergent encased single walled carbon nanotube is optically responsive to the hydrogen peroxide concentration in the environment.  
     
     
         13 . The biosensor of  claim 12 , wherein the at least one detergent encased single walled carbon nanotubes is further wrapped by one or more enzyme molecules to form a solution of detergent encased single walled carbon nanotubes with the enzyme.  
     
     
         14 . The biosensor of  claim 13 , wherein the hydrogen peroxide may be produced by an enzyme as one of the turnover products from a corresponding substrate.  
     
     
         15 . The biosensor of  claim 10 , wherein the chemical property is glucose concentration in an environment, the detergent encased single walled carbon nanotube is further wrapped by one or more glucose oxidase that may covert the glucose to hydrogen peroxide and gluconic acid, and the at least one detergent encased single walled carbon nanotube with glucose oxidase is optically responsive to hydrogen peroxide that is produced from the glucose by glucose oxidase in the environment.  
     
     
         16 . A surface modified single walled carbon nanotube, comprising, 
 a. a single walled carbon nanotube that has a layer of carbon atoms forming a wall defining a cavity therein, wherein the wall as formed has an outer surface and an inner surface, and a first end and an opposite, second end; and    b. at least one molecule non-covalently attached at least to one of the inner surface and the outer surface of the single walled carbon nanotube,    wherein the single walled carbon nanotube is at least partially surface modified with the at least one molecule to show an optical dependence of a chemical property of an environment.    
     
     
         17 . The surface modified single walled carbon nanotube of  claim 16 , wherein the single walled carbon nanotube comprises one of a semiconducting nanotube and a metallic nanotube.  
     
     
         18 . The surface modified single walled carbon nanotube of  claim 17 , wherein the dependency of the chemical property of the surfaced modified single wall nanotube shown optically is more sensitively related to the semiconducting nanotube than the metallic nanotube.  
     
     
         19 . The surface modified single walled carbon nanotube of  claim 16 , wherein the chemical property dependence of the surface modified single walled carbon nanotube is reversible.  
     
     
         20 . The surface modified single walled carbon nanotube of  claim 16 , wherein the at least one molecule comprises one of SDS, glucose oxidase, single stranded DNA, double-stranded DNA and PSS.  
     
     
         21 . The surface modified single walled carbon nanotube of  claim 16 , wherein the chemical property is one of pH value, hydrogen peroxide concentration, glucose concentration and ethanol concentration of the environment.  
     
     
         22 . A method of detecting a chemical compound, comprising the steps of: 
 a. providing a solution of surface modified single walled carbon nanotubes, wherein each of the surface modified single walled carbon nanotubes is at least partially wrapped by one or more detergent molecules to make it soluble;    b. associating the solution of surface modified single walled carbon nanotubes with the chemical compound; and    c. detecting optically a chemical property change of the solution of surface modified single walled carbon nanotubes corresponding to the chemical compound so as to detect the chemical compound.    
     
     
         23 . The method of  claim 22 , wherein the detergent comprises SDS, PSS or a combination of them.  
     
     
         24 . The method of  claim 22 , wherein the associating step comprises a step of forming a solution of the surface modified single walled carbon nanotubes and the chemical compound.  
     
     
         25 . The method of  claim 22 , wherein the chemical compound comprises at least one of a base and acid, and the corresponding chemical property is pH of the solution of the surface modified single walled carbon nanotubes.  
     
     
         26 . The method of  claim 22 , wherein the chemical compound is hydrogen peroxide, and the corresponding chemical property is hydrogen peroxide concentration in the solution of the surface modified single walled carbon nanotubes.  
     
     
         27 . The method of  claim 22 , further comprising the step of adding an amount of glucose oxidase to the solution of the surface modified single walled carbon nanotubes before the associating step so that at least one of the plurality of surface modified single walled carbon nanotubes is further wrapped by one or more glucose oxidase molecules.  
     
     
         28 . The method of  claim 27 , wherein the chemical compound is glucose, and the corresponding chemical property is glucose concentration in the solution of the surface modified single walled carbon nanotubes with glucose oxidase.  
     
     
         29 . The method of  claim 28 , wherein the glucose oxidase may convert glucose to hydrogen peroxide and gluconic acid, and the optically detecting step comprises a step of measuring the optical properties of the solution of the surface modified single walled carbon nanotubes with glucose oxidase responsive to the concentration of the hydrogen peroxide that is produced from glucose by glucose oxidase in the solution of the surface modified single walled carbon nanotubes with glucose oxidase.  
     
     
         30 . The method of  claim 22 , wherein the method further comprises the step of adding an amount of enzyme to the solution of the surface modified single walled carbon nanotubes before the associating step so that at least one of the plurality of surface modified single walled carbon nanotubes is further wrapped by one or more of the enzyme molecules.  
     
     
         31 . The method of  claim 30 , wherein the chemical compound is an substrate of the enzyme that is convertable to hydrogen peroxide as one of its turnover products by the enzyme, and the corresponding chemical property is the substrate concentration in the solution of the surface modified single walled carbon nanotubes with the enzyme.  
     
     
         32 . The method of  claim 22 , wherein the chemical compound is iodine, and the corresponding chemical property is the iodine concentration in the solution of the surface modified single walled carbon nanotubes.  
     
     
         33 . The method of  claim 22 , wherein the chemical compound is oxidant, and the corresponding chemical property is the oxidant concentration in the solution of the surface modified single walled carbon nanotubes.  
     
     
         34 . The method of  claim 22 , before the associating step, further comprising the steps of: 
 a. adding an amount of glucose oxidase to the solution of the surface modified single walled carbon nanotubes so that at least one of the surface modified single walled carbon nanotubes is further wrapped by one or more glucose oxidase molecules; and    b. adding an amount of iodide to the solution of the surface modified single walled carbon nanotubes with glucose oxidase.    
     
     
         35 . The method of  claim 34 , wherein the chemical compound is iodine that is produced in situ from the reaction of iodide with hydrogen peroxide, which is produced from glucose by the glucose oxidase, and the chemical property is the iodine concentration in the solution of the surface modified single walled carbon nanotubes.  
     
     
         36 . A method of optically detecting a chemical property change in a solution of surface modified single walled carbon nanotubes induced by sonication, comprising the steps of: 
 a. providing a solution of surface modified single walled carbon nanotubes, wherein each of the surface modified single walled carbon nanotubes is at least partially wrapped by one or more detergent molecules to make it soluble;    b. performing a sonication on the solution of surface modified single walled carbon nanotubes; and    c. detecting optically the response of the solution of surface modified single walled carbon nanotubes to a chemical property change of the solution of the solution of surface modified single walled carbon nanotubes induced by the sonication.    
     
     
         37 . The method of  claim 36 , wherein the detergent comprises SDS, PSS or a combination of them.  
     
     
         38 . The method of  claim 36 , wherein the sonication is performed at a frequency in the range of from 20 to 200 kHz for a time period of from 0 to 200 minutes at a temperature in the range of from 0 to 100° C.  
     
     
         39 . The method of  claim 36 , wherein the chemical property is pH in the solution of surface modified single walled carbon nanotubes.  
     
     
         40 . The method of  claim 39 , wherein the chemical property change is corresponding to nitrous acid and nitric acid concentrations induced by sonication in the solution of surface modified single walled carbon nanotubes.