Optical detection of choline and acetylcholine based on H2O2-sensitive quantum dots

In this paper, we have constructed a simple, rapid and sensitive biosensor for detection of choline and acetylcholine (ACh) based on the hydrogen peroxide (H2O2)-sensitive quantum dots (QDs). The detection limit for choline was 0.1 mu M and the linear range was 0.1-0.9 mu M and 5-150 mu M, respectively. The detection limit for ACh was found to be 10 mu M and the linear range was 10-5000 mu M. The wide linear ranges were shown to be suitable for routine analyses of choline and ACh. Possible mechanism of the fluorescence of QDs quenched by H2O2 was an electron transfer (ET) process. The experimental conditions of biosensors were optimized, and anti-interference ability was also presented. We also detected the choline in milk samples and the linear range was 5-150 mu M. The detection linear range of ACh in serum was 10-140 mu M. Most importantly, the recovery of choline in milk and ACh in serum samples were both close to 99%. The excellent performance of this biosensor showed that the method can be used in practice detection of choline and ACh. (C) 2011 Elsevier B.V. All rights reserved.