Construction And Application Research Of Nano-Fluorescent Probes Based On Quantum Dots And Nanoclusters

With the widespread use of antibiotics,the problem of bacterial resistance has become more and more serious.Moreover,the accumulation of harmful substances such as heavy metals and toxic chemicals through the food chain can be harmful to human health.Therefore,the monitoring of antibiotics and harmful substances is of great importance.Most traditional detection methods can achieve high sensitivity and high accuracy detection of antibiotics and harmful substances,but there are limitations such as the need to rely on large-scale instruments,long analysis time,and harsh analysis conditions.With the development of nanomaterials and synthetic technology,especially the rise of fluorescent nanomaterials,it provides new ideas for the detection of antibiotics and harmful substances.Fluorescent nanomaterials are used to construct fluorescent probes.Fluorescent probes are suitable for the detection of non-fluorescent or weakly fluorescent substances,which expanded application range of fluorescence method.At the same time,the fluorescence method has the advantages of high sensitivity,good selectivity,and short analysis time.Therefore,nano-fluorescent probe technology has developed rapidly in recent years.This paper proposes to synthesize nano-fluorescent probes such as quantum dots and nanoclusters for high sensitivity and selective detection of copper ions,picric acid and tetracycline,respectively,in order to provide new methods for the detection of antibiotics and harmful substances.The main research works and results of this article are as follows:?1?Copper ion was detected using MPA-Mn@ZnS QDs as a ratiometric fluorescent probe.Mn@ZnS QDs were synthesized by the hot-sol method,and the surface was modified with MPA to enhance its water solubility.The obtained MPA-Mn@ZnS QDs probe solution had emission peaks at 430 nm and 590 nm.After the addition of copper ions to the probe solution,the peak at 590 nm was significantly quenched while the change at 430 nm was small.Fitting (I₄₃₀/I₅₉₀)/(I₄₃₀/I₅₉₀)0 to copper ion concentration linearly,a linear equation was obtained in the concentration range of 0.3 3.0 mM,R² = 0.987,and the detection limit was 14.5 n M.Selectivity and anti-interference experiments were performed by adding different metal ions to the probe solution.It was found that only copper ions had a significant response and other metal ions did not significantly interfere.Therefore,the probe can be considered to have good selectivity for copper ions.?2?CuNC-CA was synthesized as a “Turn-off” fluorescent probe for detecting picric acid.Cysteamine were used to modify and enhance the fluorescence of copper clusters,which provided the basis for the construction of “Turn-off” fluorescent probe.Picric acid can quench the fluorescence of CuNC-CA,and linearly fit log10?I0/I?with picric acid concentration.A fitting equation was obtained in the concentration range of 1 80 mM,R² = 0.992,the detection limit was 0.139 mM.Selectivity and anti-interference experiments showed that only picric acid had a significant response,indicating that the probe has good selectivity and anti-interference to picric acid.The reason is that only picric acid absorbs the excitation light.Picric acid was detected in water samples,and the recovery was between 88.04% and 98.51%.?3?Cu@ZnS QDs was used as a ratiometric fluorescent probe to detect tetracycline.Cu@ZnS QDs solution was obtained by a one-step hydrothermal synthesis method and used as probes after purification.The probe emited at 578 nm,after the addition of tetracycline,the probe fluorescence was quenched,and the fluorescence at 520 nm was enhanced.A clear blue shift could be observed in the spectrum.The color of the probe solution changed from orange yellow to green with the addition of tetracycline under ultraviolet light,which could be the basis of visual detection.This is because Zn???on the probe surface forms a green-emitting complex with tetracycline.According to the intensity change on the spectrum,the fluorescence intensity ratio?I520/I578?and the concentration of tetracycline were fitted to a standard curve,which had a good linear relationship in the range of 0.4 1.8 mM,R² = 0.981,and the detection limit was 61 n M.Selectivity experiments showed that only tetracycline antibiotics combined with the probe and emitted green light,different tetracycline antibiotics combined with the probe showed different emission peaks because they have different structures,so the probe was specific for tetracycline.