Fluorescence Sensors Based On Silicon Quantum Dots And Their Applications In Biochemical Analysis

Silicon quantum dots(SiQDs),as fluorescent nanomaterials,have special properties including excellent photoelectric properties,good biocompatibility,high biodegrability,nontoxicity,etc.Therefore,they are widely used in biological sensor,photoelectric and energy fields,etc.what was more,we designed several fluorescent sensors for the determination of dopamine,copper ion and ascorbic acid.The advantages of these sensors are convenience,low-cost,high sensitivity and high selectivity.The main contents are summarized as follows:1.In this work,based on the DA can reduce Ag＋ into AgNPs followed by oxidized to DA-quinone,we developed a novel SiQDs-based electron transfer fluorescent sensor for the detection of DA.As electron transfer acceptor,the AgNPs and DA-quinone can quench the fluoresecnce of SiQDs effectively through the synergistic electron transfer effect.Compared with traditional fluorescence DA sensors,the proposed synergistic electron transfer-based sensor improves the detection sensitivity to a great extent(at least 10-fold improvement).The proposed sensor shows a low detection limit,which is as low as 0.1 nM under the optimal conditions.This sensor has potential applicability for the detection of DA in practical sample.This work has been demonstrated to contribute to a substantial improvement in the sensitivity of the sensors.It also gives new insight into design electron transfer-based sensors.2.A SiQDs-based fluorometric method for sensitive and selective detection of Copper ions(Cu2)was described.It is based on the catalytic action of Cu2+ on the oxidation of cysteine(Cys)by oxygen to form cystine and the by-product H2O2.The generated H2O2 is catalytically decomposed by Cu2+ to generate hydroxyl radlcals which oxidize and destroy the surface of SiQDs.As a result,the fluorescence of the SiQDs is quenched.The method has excellent selectivity due to the dual catalytic effects of Cu2,which is much better than most previously reported nanomaterial-based assays for Cu2.Under the optimal conditions,the method has low detection limit(29 nM)and a linear response in a concentration range of 0.05μM to 15μM.The method has been successfully applied to the determination of Cu2+ in spiked real water samples.3.A highly efficient and sample fluorescence sensors based on SiQDs for Ascorbic acid(AA)sensing was developed.The fluorescence of SiQDs can be quenched due to fluorescence resonance energy transfer(FRET)process from SiQDs to the generated CoOOH nanoflakes.But in the presence of AA,CoOOH nanoflakes were decomposed on account of its specific redox reaction with the enediol group of AA,and then the fluorescence of SiQDs can be recovered.The method has excellent selectivity depended on the strong reduction of ascorbic acid.Under the optimal conditions,the method has low detection limit(49 nM)and a linear response in a concentration range of 1μM to 20 μM.The method has been successfully applied to the determination of AA in vitamin C soluble tablets.