CdSe quantum dots-sensitized chemiluminescence system and quenching effect of gold nanoclusters for cyanide detection.

An efficient chemiluminescence resonance energy transfer (CRET) induced chemiluminescence (CL) system was developed for the sensitive determination of cyanide ion (CN) in environmental and biological samples. The selected CL reaction was hydrogen peroxide (HO)-bicarbonate (HCO) system with an ultra-weak emission at about 470 nm. It was found that glutathione-stabilized CdSe quantum dots (CdSe QDs) superbly increase the obtained CL intensity. The high performance CRET between the CL emitters and CdSe QDs with a broad absorption was mainly responsible for the observed improving effect. The absorption spectrum of QDs completely overlaps with the CL emission wavelength of HO-HCO system. Besides, CdSe QDs could also catalyze the CL reaction of HO-HCO, efficiently. On the other hand, it was observed that the gold nanoclusters (Au NCs) could prohibit the CRET system and turn off the CL emission. This diminishing effect can be useful for the analytical application. Herein, it was successfully exploited for the selective recognition of CN, using its leaching effect on Au NCs. After efficient dissolution of NCs, the CRET to CdSe QDs restored and the CL emission was again turned on. This strategy resulted in a high sensitive and reliable measurement of CN in the concentration range of 2-225 nM, with a detection limit of 0.46 nM.