Environmentally Friendly Quantum Dot-based Multicolor Fluorescent Probes And Their Visual Detection Of Hg²⁺and Antibiotics

With the continuous progress of human science and technology,nano-scale fluorescent sensors have obvious advantages such as sensitivity,rapidity,accuracy,and harmless target analytes,which have played an important role in human health protection and environmental monitoring.Environmentally friendly quantum dots,such as carbon quantum dots（CDs）and In P/Zn S quantum dots,have unique optoelectronic properties,low cytotoxicity,and good biocompatibility,which can be used to construct probes for the detection of target analytes.In this paper,two ratiometric nano-fluorescent probes are constructed based on environmentally friendly quantum dots for monitoring mercury ions and tetracyclines in the environment,which may have significant impacts on water pollution in the environment and global human health.The first part:as a highly toxic and carcinogenic pollutant,heavy metal ion mercury(Hg²⁺)is ubiquitous in the environment,especially in water,and has biological accumulation,so high selectivity and sensitive monitoring of mercury ions are necessary.In this paper,a one-pot method was used to construct a ratiometric dual-emission nano-fluorescent probe CDs/In PQDs@ZIF-8 based on an environmentally friendly quantum dot and MOFs（ZIF-8）sensing platform,which can be effectively used for mercury ions and cysteine Multicolor fluorescence sequential detection of amino acids（Cys）.Environmentally friendly quantum dots are blue fluorescent carbon quantum dots（CDs）and red light emitting In P/Zn S semiconductor quantum dots（In PQDs）.Among them,CDs were used as a stable reference signal,and In PQDs were used as multicolor sensing and response units for the target analytes Hg²⁺and Cys.The high sensitivity and selectivity of this nanosensor meet the current limit of the highest level of Hg²⁺in water.Combining the sensor with a smartphone color recognition APP enables fast and instant sensing of target analytes.In addition,the fluorescent nanosensor was applied to the logic gate circuit to realize the semi-quantitative analysis of Hg²⁺and Cys.This is the first example of the application of environmentally friendly In PQDs to Hg²⁺and Cys multicolor sensing,which provides a reference for the construction of environmentally friendly quantum dot-based nanosensors in the field of toxic monitoring.The second part:antibiotic contamination and resistance caused by the overuse of the antibiotic tetracycline（TC）have become a worldwide phenomenon,and it is necessary to accurately,simply and rapidly measure TC in nature.In this paper,lignite-based CDs were simply prepared and combined with rare earth ions for high-sensitivity monitoring of TC.That is,using lignite as the carbon source precursor,blue-emitting CDs were prepared by selective etching with formic acid/H₂O₂,and the CDs were used as the fluorescence response platform to synthesize a ratiometric fluorescence sensor functionalized with europium ion(Eu³⁺)（CDs-Eu）.The fluorescence sensing system can efficiently and sensitively respond to TC,and realize visual sensing from blue to red under ultraviolet light.In addition,the sensor combined with a mobile phone APP can be used for the detection of tetracycline in food samples.This method provides an important reference for the efficient and clean utilization of coal and its derivatives,and the visual sensing and detection of small molecules and drugs.47 figures,8 tables,and 191references.