Development Of Label-free Fluorescent Probes For The Biological Small Molecules Detection

Fluorescence method has been widely used in biological analysis,medical diagnosis,disease monitoring and so on due to its high sensitivity,low detection limit and maneuverability.Fluorescent sensing can be divided into two types: label and label-free.Since the label process usually requires expensive and complicated preparation process,the development of label-free fluorescent sensors is of great value.We used gold nanoclusters and organic dyes as label-free fluorescent probes to build fluorescent signal detection platform,which respectively achieved the quantitative analysis of bilirubin,and biothiols.The main contents as follows:Gold nanoclusters(HSA-AuNCs)protected by human serum albumin were mixed with bilirubin,and made gold nanoclusters aggregated due to the specific interaction between bilirubin and HSA,which led to the fluorescence quenching.A rapid method for the detection of bilirubin in solution was established by the detection strategy of gold nanoclusters quenching.The linear range of 1-40 ?M was obtained with a detection limit of 0.86 ?M.In addition,we made gold nanoclusters into paper chips,which realized the visual detection of bilirubin.The linear range of 1-20 ?M was obtained with a detection limit of 1 ?M.This method had meet the detection of bilirubin in human serum.The fluorescence of murexide was quenched when Hg(?)combined with murexide.The fluorescence of the Mu-Hg(?)was recovered gradually with the addition of biothiols such as GSH,Cys or Hcy due to their stronger affinity with Hg(?).A good relationship was obtained from 0.1-40 ?M for GSH,from 0.5-30 ?M for Cys and from0.5-50 ?M for Hcy,respectively with a detection limit of 0.02 ?M,0.01 ?M and 0.04?M.This method had successfully applied to the detection of GSH,Cys and Hcy in human urine and serum samples with satisfactory results.The UV spectrum was changed caused by the specific interaction between theprobe and cadmium ion based on murexide as the indicator.The linear range was 0-35?M with a detection limit of 0.21 ?M.We had successfully used in the detection of cadmium ion in rice.