Bi³⁺掺杂银基量子点纳米酶合成及对食品污染检测应用的研究

【作者】 冯静；

【导师】 严正权；

【作者基本信息】 曲阜师范大学 ， 分析化学， 2025， 硕士

【摘要】 环境污染是当今“关系民生”的重大课题之一。尽管文献报道了系列分析检测方法,可以对环境污染进行有效的检测,但一般存在实验仪器昂贵、不能便携、过程复杂、无法野外即时有效检测等缺点。鉴于此,本论文拟通过均相还原自组装法,开发了一类具有优异的模拟过氧化酶活性及内在荧光性能的Bi3+掺杂银基量子点纳米酶,即:Bi3+掺杂Ag量子点(Bi3+-Ag QDs);银-金-铋三金属量子点(Bi3+-Au-Ag QDs)和金-银双金属量子点(Au-Ag QDs),实现比色、掌式RGB和荧光等多模式检测实际样品中重金属离子(Hg2+,Ag+)和阴离子(S2-,NO2-)等污染物。本文主要内容概述如下:(1)Bi3+掺杂Ag量子点荧光-比色双模式检测S2-及可视识别NO2-:采用均相还原自组装的方法,首次制备了一种Bi3+掺杂银量子点(Bi3+-Ag QDs)。Bi3+-Ag QDs不仅具有本征荧光性能,还具有优异的协同模拟过氧化酶性能,可以快速催化3,3’,5,5’-四甲基联苯胺(TMB)和 H2O2 的氧化还原,Km/Vmax 分别为 0.087 mM/6.61-8 M·s-1 和6.42 mM/6.25×10-7M·s-1,呈现出明显的催化信号放大作用。痕量S2-可以选择性地改变Bi3+-Ag QDs的模拟过氧化酶活性及本征荧光特性,呈现出显著的减色效应(体系由蓝色变成无色)和“turn-on”荧光效应;而微量NO2-却可使Bi3+-Ag QDs-TMB-H2O2体系呈现出增色效应(由浅蓝色变成深蓝色)。在优化条件下,Bi3+-Ag QDs成功地应用于食品样品中S2-比色-荧光双模式识别和NO2-的可视检测,回收率分别为100.7-107.9%/95.8-104.7%和97.2-104.8%。讨论并给出了Bi3+-Ag QDs的协同仿酶催化机制及其对S2-和NO2-的选择性催化识别原理。(2)一种高性能模拟过氧化酶Bi3+-Au-Ag QDs及其紫外-荧光-掌式RGB检测超痕量S2-、Hg2+和Ag+:为了便携、高效检测毒性重金属Hg2+、Ag+以及阴离子S2-,设计制备了了一种银-金-铋三金属量子点纳米酶(Bi3+-Au-Ag QDs)。借助于Bi、Au、Ag和叶酸(FA)之间极强的协同效应,Bi3+-Au-Ag QDs表现出优异的模拟过氧化酶活性和内在的荧光性能,可以快速加速无色3,3’,5,5’-四甲基联苯胺(TMB)氧化为蓝色oxTMB,m/Vmax为0.14 mM/4.69×108 M·s-1。超微量毒性 Hg2+或 S2-会使目标 Bi3+-Au-Ag QDs-TMB-H2O2 体系的蓝色加深或褪色,呈现出可视的增色或减色效应。此外,S2-可以提高Bi3+-Au-Ag QDs的本征荧光强度,Hg2+和Ag+虽然均减弱其荧光强度,但具有明显的时间分辨效应。在优化条件下,Bi3+-Au-Ag QDs成功应用于UV-vis/智能手机辅助RGB检测食品样品中Hg2+和S2-,检出限分别为和6.48×10-9/7.22×10-9mol·L-1;荧光或时间分辨荧光检测 S2-、Ag+和 Hg2+的检出限分别为4.75×10-10 mol·L-1,1.87×10-9mol·L-1和6.97×10-10 mol·L-1,满足世界卫生组织(WHO)对饮用水的健康要求。最后,讨论了 Bi3+-Au-Ag QDs的协同仿酶催化机制及双模式催化识别Hg2+、Ag+和S2-的机理。(3)金-银双金属量子点纳米酶及荧光、紫外-可见和智能RGB检测和去除食品样品中的毒性Hg2+和S2-:为了便携、高效地检测和去除食品样品中毒性Hg2+和S2-,探讨Bi3+掺杂对银基量子点性能的影响,设计合成了一种金-银双金属量子点纳米酶(Au-Ag QDs)。叶酸(FA)、银(Ag)和金(Au)间强相互作用赋予了目标Au-Ag QDs优异的模拟过氧化酶活性,可以加速3,3’,5,5’-四甲基联苯胺(TMB)的氧化还原,Km/Vax为0.28 mmol·L-1/6.40×10-8 mol·L-1·s-1。微量的Hg2+或S2-可以选择性地改变其模拟过氧化酶活性和固有的荧光性能,对Hg2+展现出明显的增色/“turn-off”荧光效应,对S2-具有明显的减色/“turn-on”荧光效应。在优化条件下,借助于智能手机红绿蓝(RGB)值分析,Au-Ag QDs应用于紫外-可见、荧光和RGB多模式检测食品样品中Hg2+或S2-,检出限分别为3.68×10-9/2.86×10-10/2.46×10-8 mol·L-1和6.23×10-8/1.40×10-9/1.81×10-7mol·L-1,均满足WHO对健康饮用水要求。尤其是,检测完成后,仅通过简单的离心分离,即可除去93.8%以上的Hg2+和90.5%以上的S2-,无毒、无污染。更多还原

【Abstract】 Environmental pollution is one of the key issues concerning people’s livelihood nowadays.Although a series of effective instrumental analysis and detection methods have been reported for efficient monitoring of environmental pollutions in the literatures,they often needed expensive experimental instruments and complicated analytical processes,which could not be applied for on-site,real-time and portable detection in practices.In this paper,a class of Bi3+doped silver-based quantum-dot nanozymes with excellent peroxidase-like and fluorescence properties were developed by homogeneous reduction self-assembly method,by virtue of the synergistic effect between folic acid,Bi3+,Ag and other noble metal,i.e.,Bi3+doped Ag quantum dots(Au-Ag QDs),Bi3+-Au-Ag trimetallic quantum dots(Bi3+-Au-Ag QDs)and gold-silver quantum dots(Au-Ag QDs).were synthesized respectively.Under the optimized conditions,they were applied for colorimetric,RGB palm and fluorescent detection of heavy metal ions(Hg2+,Ag+)and toxic anions(S2-,NO2-)in real food samples.In this dissertation,the main contents are illustrated as follows:1.Folic acid capping Bi3t-doped Ag quantum dots for enzyme-like dual-mode recognition of toxic S2-and visual sensing of NO2-:A kind of Bi3+-doped Ag quantum dots(Bi3+-Ag QDs)was developed for the first time by one-pot homogeneous reduced self-assembly.Not only did Bi3+-Ag QDs possess intrinsic fluorescent property,it expressed synergistic peroxidase-like activity to catalyze the redox of 3,3’,5,5’-tetramethylbenzidine(TMB)and H2O2 with Km/Vmax of 0.087 mM/6.61-8 M-s-1 and 6.42 mM/6.25×10-7 M·s-1 respectively.Interestingly,trace S2-could exclusively alter its fluorescent property and peroxidase-like activity,exhibiting significant hypochromic and "turn-on" fluorescent effects.While trace NO2could make Bi3+-Ag QDs-TMB-H2O2 system hyperchromic.Under the optimized conditions,Bi3+-Ag QDs were applied for dual-mode recognition of S2-and visual sensing of NO2-in real food samples with satisfactory recoveries,i.e.,100.7-107.9%/95.8-104.7%and 97.2-104.8%respectively.The synergistic enzyme-mimic mechanism of Bi3+-Ag QDs and its selective response mechanisms to S2-and NO2-were also proposed.2.A high-efficiency Bi3+-Au-Ag quantum dot peroxidase mimic for UV-vis,fluorescent and palm-type RGB monitoring of ultra-trace toxic S2-,Hg2+and Ag+practically:For potable and high-efficiency monitoring of toxic anion S2-,heavy-metal Hg2+and Ag+,a kind of Bi3+-Au-Ag tri-metal quantum dots(Bi3+-Au-Ag QDs)was developed in this work.By virtue of the synergistic effect among Bi,Au,Ag and folic acid(FA),Bi3+-Au-Ag QDs expressed excellent peroxidase-like activity and fluorescent performance,which could accelerate the oxidization of colorless 3,3’,5,5’-tetramethylbenzidine(TMB)into blue oxTMB with Km/Vmax of 0.14 mM/4.69×10-8 M·s-1.Ultra-trace toxic Hg2+or S2-could exclusively deteriorate or deepen the blue color of Bi3+-Au-Ag QDs-TMB-H2O2 system.Moreover,S2could improve the intrinsic fluorescent intensity of Bi3+-Au-Ag QDs,while Hg2+ and Ag+weakened it with a clear time-resolved effect.Under the optimized conditions,Bi3+-Au-Ag QDs was successfully applied for UV-vis/smartphone-assisted RGB monitoring of Hg2+and S2-in real agricultural products,with detection limits of 3.74×10-9/6.63×10-9 mol·L-1 and 6.48×10-9/7.22×10-9 mol·L-1.And the ones for "turn-on" fluorescent or time-resolved fluorescent differentiation were 4.75×10-10 mol·L-1.87×10-9 mol·L-1 and 6.97×10-10 mol·L-1 for S2-,Ag+ and Hg2+ respectively.All the detection results well met the requirement values in drinking water by World Health Organization.The probable recognition mechanisms were also proposed in detail.3.Au-Ag quantum dot nanozyme identified for multi-mode fluorescent,UV-vis and intelligent RGB monitoring and removal of toxic Hg2+ and S2-in food samples:To conveniently monitor and remove toxic Hg2+ and S2-in food samples,Au-Ag quantum-dot nanozyme(Au-Ag QDs)was identified.The strong synergistic effect among folic acid(FA),Ag and Au endowed Au-Ag QDs with superior peroxidase-mimic activity to accelerate 3,3’,5,5’-tetramethylbenzidine(TMB)redox with Km/Vmax of 0.28 mmol·L-1/6.40×10-8 mol·L-1·s-1.Trace Hg2+ or S2-could selectively alter its peroxidase-like activity and inherent fluorescence performance,with obvious hyperchromic/"turn-off" fluorescent effect for Hg2+or hypochromic/"turn-on" one for S2-.And red-green-blue(RGB)values analyzed from smartphones changed regularly with cHg2+ or cs2-.Under the optimized conditions,Au-Ag QDs were successfully applied for multi-mode UV-vis,fluorescent,and RGB monitoring of Hg2+or S2-in food samples.The detection limits were 3.68×10-9/2.86×10-10/2.46×10-8 mol·L-1 and 6.23×10-8/1.40×10-9/1.81×10-7 mol·L-1 respectively,well meeting with the permitted values of 3.0×10-8 mol·L-1/0.6 mmol·L-1 for Hg2+/S2-in drinking water by WHO.What’s more,over 93.8%Hg2+or 90.5%S2-could be removed by simple centrifugalization after detection.The selective recognition mechanisms to Hg2+ and S2-were also proposed.更多还原