Regulable Synthesis Of Fluorescent Silicon Nanomaterials And Exploration Of Their Applications As Fluorescence Sensors,Catalysts And Antibacterial Agents

Fluorescent silicon-based nanomaterials have excellent optical,electrical properties,biocompatibility and low/non-toxicity,which are widely used in photoelectric devices,energy catalysis,fluorescence sensing and other fields.Although there are many related researches,there are still some problems to be solved.For example,how to improve the sensitivity and selectivity of fluorescent silicon-based nanomaterials as fluorescence sensors;how to give full play to other properties of fluorescent silicon-based nanomaterials apart from fluorescence.In this thesis,in order to realize the rapid and highly sensitive on-site detection of drug molecules,catalytic degradation of drugs,and development of new nano antibacterial agents,a series of explorations were carried out from the regulable synthesis and multifunctional applications of fluorescent silicon nanomaterials with 3-aminopropyl trimethoxysilane as silicon source and selecting suitable compounds as dopants.The details are as follows:1.In order to achieve simple regulation and preparation of multicolor fluorescent silicon quantum dots,neutral red was selected as the dopant to prepare a series of silicon quantum dots by hydrothermal method under the different conditions,and the mechanism of fluorescence color change was explored.Due to the complexation between the surface functional groups of silicon quantum dots and Cu²⁺,a fluorescence sensor for Cu²⁺detection was constructed.It can be used for the detection of Cu²⁺in real samples and intracellular Cu²⁺imaging detection.In this chapter,multicolor fluorescent silicon quantum dots were prepared by simple dye doping and the control of reaction conditions,which provided a new idea for the synthesis of silicon quantum dots with adjustable fluorescence performance.2.For the purpose of specific detection of dopamine of the catecholamines,3-aminophenobenic boric acid was selected as dopant to prepare a series of silicon quantum dots by solvothermal method under the different conditions.By comparison,it was found that doping not only changed the fluorescence properties of the product,but also changed the response of the product to dopamine from fluorescence quenching to fluorescence enhancement,which could distinguish dopamine from other two catecholamines.Based on this,a fluorescence colorimetric sensor was constructed by combining prepared silicon quantum dots with gold nanoclusters,which could realize semi-quantitative detection of dopamine by the naked eyes.Further combined with smart phone APP,rapid quantitative on-site detection of dopamine can be achieved without instruments.The research results in this chapter showed that the properties of silicon quantum dots can be adjusted by selecting appropriate dopants,so as to achieve high specificity detection of specific target substance.3.In order to simultaneously detect and remove tetracycline antibiotics（TCs）in water,thiourea was selected as dopant to synthesize sulfur and nitrogen co-doped silicon nanoparticles.The blue fluorescence of the materials can be selectively quenched by TCs due to internal filtration effect,accompanied by yellow-green fluorescence shown due to aggregation induced fluorescence emission effect,thus the silicon nanoparticles can be used as colorimetry fluorescent probes for detection of TCs.In addition,the prepared materials can also be used as a catalytic degradation agent of TCs under ultraviolet light due to hydroxyl radical,superoxide radical and singlet oxygen produced,significantly accelerating the oxidative degradation of these substances.This silicon-based nanomaterial realized the integrated application of colorimetric detction and catalytic degradation of TCs,and can monitor the degradation of TCs at the same time of catalytic degradation.This chapter innovatively proposed an integrated probe for the detection and catalytic degradation of antibiotics,providing a new strategy for rapid and simple detection and removal of drug molecules.4.Tetraethylenepentamine（TEPA）was selected as dopant to prepare a novel multifunctional nitrogen-doped silicon quantum dots（N-SiQDs）by one-pot hydrothermal method.The N-SiQDs prepared can be used not only as fluorescent imaging probes,but also as a reducing agent and stabilizer to synthesize hybrid gold nanoparticles with excellent catalytic performance under mild conditions.In addition,the experimental results indicated that N-SiQDs showed good antibacterial performance against S.aureus and E.coli,which has the potential to be used as nano antibacterial agent.This study provides an example for expanding the multiple applications of silicon quantum dots.Secondly,considering the environmental pollution and human health problems caused by the use of nanomaterials,starting from the properties of TEPA,a composite material was prepared using amorphous silicon dioxide as substrate and TEPA as modifier for removal of silver nanoparticles,which are widely used at present.The results showed that its removal performance was better than other coagulants reported at present.This study provides a feasible idea for the efficient removal of other nanoparticles.