碳点合成及用于检测汞离子的碳点荧光传感器研究进展

Research progress of synthesis of carbon dots and fluorescent sensor based on carbon dots for mercury detection

汞离子(Hg^2+)具有持久性、易迁移性、易富集性等特点,会严重破坏农作物的生长环境,影响农作物的发育,进一步威胁农产品的质量安全和人类身体健康。荧光法操作简便,灵敏度高。其中,荧光探针是影响荧光分析性能的关键因素。碳点(Carbon Dots,CDs)具有制备简单、荧光效率高、生物相容性好等优点,基于CDs构建的荧光传感器在农业信息感知领域引起了广泛的关注。该研究主要综述了基于生物质来源的CDs合成、基于CDs传感器的构建及其在农业传感领域的应用。着重介绍了基于CDs构建的荧光猝灭型、荧光增强型、比率型荧光传感器在Hg^2+检测方面的应用及研究进展,总结了不同分析模式中所用的探针材料、实际样品及检测Hg^2+的分析性能情况,并对比了不同分析模式的优缺点。最后,分析了基于CDs构建的荧光传感器在农业传感领域的瓶颈问题及发展趋势,指出开发便携式设备实现Hg^2+或多组分的同时、快速、可视化检测是本领域的发展方向。

Mercury ion(Hg^2+)is one of the most frequently occurring and most toxic heavy metal pollutants,which may seriously damage the growth environment of crops and further threaten the quality and safety of agricultural products and human health.Fluorescence analysis is a simple method of Hg2+detection with high sensitivity.The analysis performance of fluorescence sensor may be seriously affected by fluorescence probes.Carbon dots(CDs)have the advantages of simple preparation,high fluorescence efficiency,and good biocompatibility.Therefore,fluorescence sensors based on CDs have attracted wide attention.This study introduced the synthesis status of CDs prepared from biomasses such as crops,agricultural products and their wastes,and pointed out that the synthesis of CDs was rich in natural biomass materials,and CDs synthesized by ultrasonic,microwave,and hydrothermal methods have the advantages of low cost,simple preparation process,and environmental protection.In addition,the application research of fluorescence sensor based on CDs for the detection of antibiotics,pesticides,and food additives in the field of agricultural sensing was briefly introduced.Furthermore,the research progress of fluorescence sensor based on CDs in Hg^2+detection was systematically introduced from the perspectives of fluorescence quenching single-signal analysis mode,fluorescence-enhanced single-signal analysis mode and ratio-based signal analysis mode.The fluorescent materials,analytical performance and advantages and disadvantages of each method used in different sensing modes were summarized and compared.Among the single-signal sensors,fluorescence quenching sensors could optimize the detection performance of CDs by doping,surface modification,or"on-off-on"strategies;the fluorescence intensity of fluorescence-enhanced sensors ranged from weak to strong,and fluorescence colors were created from scratch,which could reduce the occurrence of false positive signals,but few fluorescence-enhanced sensors constructed by CDs as probes may occur,which needs to be further developed;The CDs with different properties could be used as reference signals,response signals as well as dual emission matrix in ratio fluorescence sensors.Besides,ratio fluorescence sensor could establish an internal standard to weaken the interference of external factors,the analysis result was more reliable and accurate,and it was easier to realize sensitive visual analysis.Different models of fluorescence sensors were all widely used in the detection of Hg^2+in lake water,soil,and agricultural products.The bottleneck and development trend of the fluorescence sensor based on CDs using biomass as the synthesis source in the field of agricultural sensing were analyzed:1)the luminescence mechanism of CDs remained unclear due to the complex composition of precursors in the preparation of CDs from crops and agricultural products.Moreover,the fluorescence quantum yield of synthesized CDs was uneven,and it needs to be separated,purified,doped or modified in a targeted manner;2)most of the CDs based fluorescent sensors could detect only one single target,while the CDs based fluorescent sensors detecting multiple targets at the same time were little reported,and most of the sensing systems were still in the experimental stage,so it was difficult to perform the on-site detection of agricultural environmental quality and crop quality.