Synthesis of mercaptoethylamine-coated CdSe/CdS nanocrystals and their use for DNA probe.

CdSe/CdS nanocrystals (NCs) have been synthesized in aqueous solution by using mercaptoethylamine as a stabilizer. The results of TEM, UV-Vis and FL spectra show that the product is of excellent crystal structure, uniform in radius, with extraordinary fluorescence characters. These CdSe/CdS NCs allow the ultrasensitive quantitative detection of DNA. Under the optimum conditions, linear relationships have been found between the relative fluorescence intensity and the DNA concentration in the ranges 0 - 10 and 10 - 100 microg mL(-1); the linear equations are DeltaF = 210 + 80.91 C and DeltaF = 946 + 10.57 C (C, microg mL(-1)), respectively. The detection limits are 0.251 and 1.920 microg mL(-1), correspondingly. The proposed method has been applied to the determination of DNA in pig liver. It is indicated that these NCs could become a newly kind of DNA probe. In addition, the mechanism of the binding reaction has also been explored. It is considered that the binding reaction is mainly due to static electricity forces.