Synthesis Of Silver Sulfide Quantum Dots Based On Polyethyleneimine And Its Application In Detection

Quantum dots are aggregates of atoms and molecules at the nanoscale scale,which are typically composed of semiconducting materials and are stable nanoparticles at 2-20 nm in diameter.As a novel semiconductor nanomaterial,quantum dots have many unique nano-properties.It has a wide range of applications in biochemistry,chemical sensors,life sciences,genomics,optoelectronic materials and other fields.Current research on quantum dots is focused on environmentally friendly near-infrared(NIR)luminescence areas,because they have higher penetration depth,lower background fluorescence,lower signal loss,the usual photochemical stability and the obvious advantages of single excitation / multiple emission than other quantum dots.Since the traditional near-infrared quantum dots generally contain heavy metal ions such as Cd2 +,Hg2 +,Pb2 +,the release of these ions can cause cytotoxicity and may be harmful to the environment potentially,which also limits the application of NIR QDs.Therefore,the design and development of innovative methods to build near infrared quantum dots has become one of the current research hotspots.Polyethylene-imine(PEI)-silver sulfide quantum dots was the object of study in this paper.We explored the synthesis of different polyethylene-imine-silver-sulfide quantum dots fluorescent material and the special optical properties and detection performance of it.In addition to that,the synthesized polyethylene-imine silver sulfide as a fluorescent material was used for biochemical testing and practical analysis.The main contents of this paper are summarized as follows:1.We successfully synthesis PEI-Ag2 S QDs and studied the optimal synthetic conditions of it.The synthesized Ag2 S QDs was characterized by TEM,UV-Vis,FL,FT-IR and other methods.The results showed that PEI-Ag2 S QDs were successfully synthesized.Therefore,we use PEI-Ag2 S QDs as a new fluorescent sensor for detecting mercury ions,and carry out fluorescence detection on mercury ions at a wide range of p H(4-10),and get the better results.It was found that the linear range of Hg2+ was 5-625 n M and the lowest detection concentration was 0.5 n M.The feasibility of PEI-Ag2 S QDs was also demonstrated in tap Water,the Yangtze River water and sand lake water,which indicated that it had a good prospect in the extensive study of mercury ions.2.We used PEI-Ag2 S QDs as a novel fluorescent sensor for the detection of heparin and heparinase I.A new type of fluorescent "turn on-off" detection method was designed by using the fluorescence aggregation induction effect and the specific hydrolysis of the enzyme.It was found that the linear ranges were 0.069-2.275 ?M and 0-103 ng?m L-1,and the lowest detection concentrations were 6 n M and 0.5 ng?m L-1,respectively.We also conducted a series of studies on the steady-state kinetics of heparinase I.At the same time,we successfully applied PEI-Ag2 S QDs to the detection of heparin and heparinase I in serum,which proved that the method was feasible in biomedicine and biochemistry.3.We successfully synthesized the Ag2 S QDs/metal organic compounds characterized it by FL,TEM,FTIR,XRD and other methods,which showed that Ag2 S QDs/metal organic compounds were successfully synthesized.We also investigated the mechanism and feasibility of the detection of phosphate.From the results,we could see that the phosphate was sensitive,the selectivity was good,the linear detection range was 0.7-88.2 ?M,and the lowest detection concentration was 0.07 ?M.In addition to that,we successfully applied the compounds to the detection of phosphate in tap water and Yangtze River water samples,which proved that the method was feasible in practicability application.