Choline Compound Enzyme Biosensor Based On Quantum Dots

With the development of nanotechnology, the application of nanomaterials inbiodetection, medical diagnostics, environmental monitoring, food industry and other fieldshas gained increasing interest. Quantum dot is a new kind of fluorescent semiconductormaterial with unique physical and chemical properties, stable fluorescence properties, lessprone to photobleaching, with a large Stokes shift of fluorescence spectra and narrowsymmetric peak. Because of these novel properties, quantum dot is an ideal material to buildoptical biosensors.Choline compound includes choline, acetylcholine acetylcholinesterase andbutyrylcholinesterase, etc. It has an important role in maintaining the normal function ofhuman body. The detection of choline compound has great significance in food industry,clinic analysis and other areas, but there still exists many problems in the detection methodsof choline compound. According to the actual demand, this paper has constructed a novelenzyme biosensor based on quantum dot. Water-soluble CdTe quantum dots were prepared bya simple method in this dissertation. The morphology and Spectra characterization of quantumdots have also been studied. The results showed that the quantum dots have uniform shape,good dispersing properties, and has very good lattice; narrow symmetrical fluorescenceemission peaks and has no tail, optical performance and stability. These excellentcharacteristics of quantum dots provide strong foundations for building stable, accurate,repeatable optical biosensor. Based on the fluorescence change of quantum dots, we constructbiosensor from "turn on" and "turn off" side. We also studied the detect conditions of thissensor. The result showed that the biosensor can work at room temperature (25~37℃), andmaintain stable detection performance. So, the sensor constructed in this paper has advantagesof mild reactive condition and easy operation. In the biosensor detection experiments, westudied the detection performance of the sensor, and, the detection principle was alsodiscussed. The results showed lower detection limit and wider detection linear range. Moreover, the introduction of interferences, such as glucose, lactic acid and ascorbic acid, wasnearly no effect on the detection signal. This indicated that the quantum point sensor has agood anti-interference ability. In addition, the practical application of this sensor was explored.The result showed that this sensor can realize the detection of choline in milk samples and acetylcholine in serum samples. The recovery of choline in milk and acetylcholine in serumare both up to99%. We have also taken repeat experiment of choline detection in milk andacetylcholine detection in serum. The relative standard deviation of repeat experiment resultswas less than5%and3%, respectively. Above all, the biosensors based on quantum dot inthis paper can meet the requirements of practical sample analysis. And, it provides the theoryreference to make biochemical analysis technique utilized and industrialized. This methodprovides several advantages such as simple work-up procedure, sensitive, shorter reactiontime, milder conditions, low cost, selectively and anti-interference. In the clinical analysis anddiagnosis, and other areas, the detection of choline compound based on this method will hasbroad application prospects.