Glucose sensor

Abstract

A method of quantifying the amount of glucose in a sample is provided herein that may further comprise an interferent such as mannitol. At least two measurements are obtained using measurement methods that differ in their sensitivity to the amount of interferent in the sample, thus enabling the results to be compared to determine whether any interferent is present in the sample. A glucose sensor for carrying out a method described herein is also provided

1 . A glucose sensor for quantifying the amount of glucose in a sample that may further comprise an interferent, the sensor comprising:
 a sensing region comprising:
 a first indicator system comprising a first receptor for binding to glucose and a first fluorophore associated with the first receptor, wherein said first receptor has an association constant K G1  with glucose and an association constant K M1  with said interferent, and 
 a second indicator system comprising a second receptor for binding to glucose and a second fluorophore associated with the second receptor, wherein said second receptor has an association constant K G2  with glucose and an association constant K M2  with said interferent, and wherein K G2 /K M2  is different from K G1 /K M1 ; and 
   an optical waveguide for directing light onto the sensing region.   
     
     
         2 . The glucose sensor according to  claim 1 , wherein said first fluorophore and said second fluorophore have peak emission wavelengths that differ by at least 5 nm. 
     
     
         3 . The glucose sensor according to  claim 1 , wherein [K G2 /K M2 ]/[K G1 /K M1 ] is greater than 2 or less than 0.5. 
     
     
         4 . The glucose sensor according  claim 1 , wherein said first receptor and said second receptor are boronic acid receptors. 
     
     
         5 . The glucose sensor according to  claim 4 , wherein said first receptor contains two boronic acid groups and said second receptor contains one boronic acid group. 
     
     
         6 . The glucose sensor according claim, wherein said interferent is selected from: (a) an interferent that comprises a cis-diol group; and (b) an amine. 
     
     
         7 . The glucose sensor according to  claim 6 , wherein the interferent that comprises a cis-diol group is selected from a sugar alcohol and a saccharide. 
     
     
         8 . The glucose sensor according  claim 1 , wherein the interferent is selected from the group consisting of mannitol, sorbitol, galactitol, inositol, fructose, galactose, arabinose, glutamine and catechol amines. 
     
     
         9 . The glucose sensor according to  claim 8 , wherein the interferent is mannitol. 
     
     
         10 . A method of quantifying the amount of glucose in a sample that may further comprise an interferent, the method comprising:
 inserting into the sample a glucose sensor comprising:
 a sensing region comprising at least a first indicator system comprising a first receptor for binding to glucose and a first fluorophore associated with the first receptor; and 
 an optical waveguide for directing light onto the sensing region; 
   providing incident light to the sensing region of the sensor and obtaining a first measurement of the amount of glucose by a first measurement method comprising detecting the emission of said first fluorophore;   obtaining a second measurement of the amount of glucose by a second measurement method, wherein the second measurement method differs in its sensitivity to the amount of said interferent in the sample from the first measurement method; and   comparing said first measurement and said second measurement and thereby determining whether any of said interferent is present in the sample;   
       wherein said interferent is a substance that is capable of interfering with the binding of glucose to said first receptor. 
     
     
         11 . A method according to  claim 10 , comprising:
 inserting into the sample a glucose sensor comprising:   a sensing region comprising:
 a first indicator system comprising a first receptor for binding to glucose and a first fluorophore associated with the first receptor, wherein said first receptor has an association constant K G1  with glucose and an association constant K M1  with said interferent, and 
 a second indicator system comprising a second receptor for binding to glucose and a second fluorophore associated with the second receptor, wherein said second receptor has an association constant K G2  with glucose and an association constant K M2  with said interferent, and wherein K G2 /K M2  is different from K G1 /K M1 ; and 
 an optical waveguide for directing light onto the sensing region; 
   providing incident light to the sensing region of the sensor;   obtaining a first measurement of the amount of glucose by a first measurement method comprising detecting the emission of said first fluorophore;   obtaining a second measurement of the amount of glucose by a second measurement method comprising detecting the emission of said second fluorophore; and   comparing said first measurement and said second measurement, thereby determining whether any of said interferent is present in the sample, and correcting for the presence of any said interferent in the sample.   
     
     
         12 . A method according to  claim 11 , wherein said first measurement and said second measurement are obtained in a single emission detection step. 
     
     
         13 . A method according to  claim 11 , wherein said first fluorophore and said second fluorophore have peak emission wavelengths that differ by at least 5 nm. 
     
     
         14 . A method according to  claim 11 , wherein [K G2 /K M2 ]/[K G1 /K M1 ] is greater than 2 or less than 0.5. 
     
     
         15 . A method according to  claim 11 , wherein said first receptor and said second receptor are boronic acid receptors. 
     
     
         16 . A method according to  claim 15 , wherein said first receptor contains two boronic acid groups and said second receptor contains one boronic acid group 
     
     
         17 . A method according to  claim 10 , wherein said sample that may further comprise an interferent is an in vivo sample. 
     
     
         18 . A method according to  claim 10 , wherein said sample that may further comprise an interferent is an in vivo sample and wherein said method comprises:
 (i) obtaining said first measurement at a time point t test ;   (ii) obtaining said second measurement by said second measurement method, wherein said second measurement method comprises electrochemically measuring the amount of glucose, or of said interferent, in the sample at said time point t test ; and   (iii) comparing said first measurement and said second measurement, thereby determining whether said first measurement contains a contribution from said interferent in the sample.   
     
     
         19 . A method according to  claim 18 , wherein the method is carried out on a human or animal subject and the sample is an in vivo bodily fluid of said subject, and wherein step (i) comprises carrying out an in vivo measurement on said bodily fluid at time t test , and wherein step (ii) comprises extracting a portion of said bodily fluid from said subject at time t test  and carrying out an in vitro electrochemical measurement thereon. 
     
     
         20 . A method according to  claim 18 , wherein said method comprises carrying out the sequence of steps (i) to (iii) one or more times, each at different time points, until in said step (iii) of comparing said first measurement and said second measurement it is determined that said first measurement contains substantially no or a reduced contribution from said interferent. 
     
     
         21 . A method according to  claim 18 , wherein in said step (iii) of comparing said first measurement and said second measurement an estimate of the amount of said interferent in the sample at t test  is obtained and wherein said method further comprises:
 (iv) allowing a sufficient time delay for any said interferent present in the sample at t test  to substantially clear the sample; and   (v) providing incident light to the sensing region of the sensor and detecting the emission of said first fluorophore, thereby obtaining a third measurement of the amount of glucose in the sample, said third measurement having substantially no or a reduced contribution from said interferent.   
     
     
         22 . A method according to  claim 10 , wherein the interferent is selected from:
 (a) an interferent that comprises a cis-diol group; and (b) an amine.   
     
     
         23 . A method according to  claim 22 , wherein the interferent that comprises a cis-diol group is selected from a sugar alcohol and a saccharide. 
     
     
         24 . A method according to  claim 10 , wherein the interferent is selected from the group consisting of mannitol, sorbitol, galactitol, inositol, fructose, galactose, arabinose, glutamine and catechol amines. 
     
     
         25 . A method according to  claim 24 , wherein the interferent is mannitol. 
     
     
         26 . A glucose sensor for quantifying the amount of glucose in a sample that may further comprise an interferent, the sensor comprising:
 a sensing region comprising:
 a first indicator system comprising a first receptor comprising two boronic acid groups for binding to glucose and a first fluorophore associated with the first receptor, and 
 a second indicator system comprising a second receptor comprising one boronic acid group for binding to glucose and a second fluorophore associated with the second receptor; and 
   an optical waveguide for directing light onto the sensing region.   
     
     
         27 . The glucose sensor according to  claim 26 , wherein said interferent comprises a cis-diol group. 
     
     
         28 . The glucose sensor according to  claim 26 , wherein said interferent is selected from the group consisting of mannitol, sorbitol, galactitol, inositol, fructose, galactose and arabinose. 
     
     
         29 . The glucose sensor according to  claim 26 , wherein said interferent is mannitol. 
     
     
         30 . The glucose sensor according to  claim 26 , wherein the first receptor has an association constant K G1  with glucose and an association constant K M1  with said interferent and the second receptor has an association constant K G2  with glucose and an association constant K M2  with said interferent, and wherein K G2 /K M2  is different from K G1 /K M1 .