Biosensors, and method and kits for using same

Abstract

A stabilised thylakoid membrane formulation comprising thylakoid membranes in a buffered solution and liposomes, wherein the formulation has a ratio of chlorophyll/liposomes of at least about 10:1. The invention further comprises a method for detecting or quantifying the presence of toxic molecules in a fluid sample, comprising obtaining a stabilised thylakoids membranes formulation; and assessing the photosynthetic efficiency of the thylakoid membranes formulation in the presence of said sample, whereby the molecules are detected when the photosynthetic efficiency is measurably different in the presence versus in the absence of the sample. The present invention also comprises kits using the stabilised thylakoid membranes formulation for detecting and/or quantifying the toxic molecule in a fluid sample.

1 . A stabilised thylakoid membrane formulation comprising thylakoid membranes in a buffered solution and liposomes, wherein the formulation has a ratio of chlorophyll/liposomes of at least about 10:1.  
     
     
         2 . A formulation as recited in  claim 1 , wherein the buffered solution has a pH between about 6,2 and about 7,8.  
     
     
         3 . A formulation as recited in  claim 1 , wherein the formulation has a ratio of chlorophyll/liposomes of between about 10:1 and 100:1.  
     
     
         4 . A formulation as recited in  claim 1 , further comprising polyvinylpyrrolidine (PVP) in a concentration lower than about 4% v/v.  
     
     
         5 . A formulation as recited in  claim 1 , wherein the liposomes are constituted of phosphatidylcholine and phosphatidylglycerol in a ratio of about 10:1.  
     
     
         6 . A kit for detecting a toxic molecule in a fluid comprising a stabilised thylakoids membranes formulation comprising thylakoids membranes in a buffered solution and liposomes, wherein the ratio of chlorophyll/liposomes is of at least about 10:1; and a portable fluorometer using non-modulated light.  
     
     
         7 . A kit as recited in  claim 6 , wherein the buffered solution has a pH between about 6,2 and about 7,8.  
     
     
         8 . A kit as recited in  claim 6 , further comprising polyvinylpyrrolidine (PVP) in a concentration lower than about 4% v/v.  
     
     
         9 . A kit as recited in  claim 6 , wherein the liposomes are constituted of phosphatidylcholine and phosphatidylglycerol in a ratio of about 10:1.  
     
     
         10 . A use of a stabilised thylakoid formulation as recited in  claim 1  for detecting or quantifying the presence of a toxic molecule in a fluid sample.  
     
     
         11 . A use as recited in  claim 9 , wherein the toxic molecule is selected from the group constituted of herbicides, metal ions, H 2 O 2 , NaCl, CaCO 3 , nitrates, phosphates, oleic acid, stearic acid, ammoniacal nitrogen and humic acid.  
     
     
         12 . A method for detecting or quantifying the presence of toxic molecules in a fluid sample, comprising 
 obtaining a stabilised thylakoids membranes formulation as recited in  claim 1;  and    assessing the photosynthetic efficiency of the thylakoid membranes formulation in the presence of said sample,    whereby said molecules are detected when said photosynthetic efficiency is measurably different in the presence versus in the absence of said sample.    
     
     
         13 . A method as recited in  claim 12 , wherein the photosynthetic efficiency is assessed with a fluorometer using non-modulated light after the thylakoid membranes formulation has been incubated with the sample for a time sufficient to enable any toxic molecules in the sample to disrupt the photosynthetic efficiency of the thylakoid membranes formulation.  
     
     
         14 . A method as recited in  claim 13 , wherein the molecules comprise a herbicide and wherein the photosynthetic efficiency assessment is conducted after the thylakoid membranes formulation has been incubated for 10 minutes.  
     
     
         15 . A method as recited in  claim 13 , wherein the molecules comprise a metal ion and wherein the photosynthetic efficiency assessment is conducted after 15 to 180 minutes.  
     
     
         16 . A method of stabilising thylakoid membranes for use in bioassays comprising mixing thylakoid membranes in a buffered solution with liposomes to yield a thylakoid membranes formulation, whereby the final ratio of chlorophyll/liposomes in the formulation is of at least about 10:1.  
     
     
         17 . A method as recited in  claim 16 , wherein the buffered solution has a pH between about 6,2 and about 7,8.  
     
     
         18 . A method as recited in  claim 16 , wherein the final ratio of chlorophyll/liposomes in the formulation is of between about 10:1 and 100:1.  
     
     
         19 . A method as recited in  claim 16 , wherein the formulation further comprises polyvinylpyrrolidine (PVP) in a concentration lower than about 4% v/v.  
     
     
         20 . A method as recited in  claim 16 , wherein the liposomes are constituted of phosphatidylcholine and phosphatidylglycerol in a ratio of about 10:1.