The Synthsis And Application Of Carbon Dots And Sliver Nanocluster

Carbon dots(CDs),as a new type of carbon nano materials,has been widely used in various research fields due to its excellent properties.Compared with traditional semiconductor quantum dots,it has better optical properties,biocompatibility and environment friendliness.This makes the carbon can be widely used in biological imaging,nano sensing,photocatalysis,optoelectronic devices and other fields.In this paper,we prepared the CDs by hydrothermal treatment and microwave-assisted method and applying to the ion detection:(1)A CDs were successfully synthesized by one-pot hydrothermal treatment of Staphylococcus Aureus(SA).The CDs without any modification exhibits excellent photoluminescence properties with an absolute quantum yield(QY)of 10%.Furthermore,the as-prepared CDs could be directly employed as a fluorophore with the task of fluorescent signal readout.In this paper,we have demonstrated a fluorescent CDs probe for detecting berberine hydrochloride(BRH)based on the inner filter effect(IFE)due to that the absorption bands of BRH fully covered the emission and excitation bands of CDs.Because of the competitive absorption,the excitation of CDs was significantly weakened,resulting in the fluorescence intensity quenching of CDs.The present IFE-based sensing strategy showed a good linear relationship from 1.0×10-7 to 7.5×10-5 mol/L(?I=16.02 + 3.79×106c,r=0.9972)and provided an exciting detection limit of 7.0 × 10-8 mol/L(signal-to-noise ratio of 3).The proposed sensing approach provides an obvious advantage of simplicity,convenience,rapid response,high selectivity and sensitivity,which have been successful application for the detection of BRH in compound berberine tablets from the drugstore.(2)In this part,the Yeast Bacteria and ethylenediamine were used as the carbon source to synthesize the CDs with microwave.The as-prepared CDs have a bright blue fluorescence.The maximum excitation wavelength of CDs is 390 nm and the maximum emission wavelength is 460 nm.Furthermore,the CDs possessed a broad-range pH response.The linear pH response range was from 1.81 to 11.82,which is much wider than that of previously reported fluorescence pH sensors.The linear equation is IF =259.90-12.61 pH,)and the correlation coefficient is r = 0.9936.(3)A fluorescent Ag nanocluster(AgNCs)was prepared by the photochemical reduction with the mixture of carboxymethyl dextran(CMD)and [Ag(NH3)2]+ under ultraviolet C(UVC)light irradiation.Further study showed that the as-prepared AgNCs had the maximum fluorescence emission peak near the located surface plasmon resonance(LSPR)wavelength of AgNCs.Thus,these AgNCs are defined as LSPR-AgNCs.The maximum excitation wavelength of AgNCs is 250 nm and the maximum emission wavelength is 425 nm.In solution,the fluorescence of AgNCs could be quenched in the presence of Cysteine.Based on this phenomenon,the AgNCs was developed as a fluorescence probe for the detection of Cysteine.The fluorescence intensity quenching value(ΔI)has a linear relationship with the concentration of Cysteine,which follows a linear equation of ΔI =4.25×109c + 36.84 with the correlation coefficient of r=0.9967 in the linear range of 5.0×10-10 to 1.0×10-7 mol/L.The detection limit(3σ/k)was 3.2 ×10-10 mol/L.