Synthesis Of Fluorescent Germanium Nanoparticles And Its Applications In Biochemical Analysis

Group ? nanomaterials have broad application prospects in biochemical analysis and bioimaging fields due to their unique physical and chemical properties.In the past decades,the preparation and property of carbon dots and silicon nanoparticles have been explored in depth.Germanium nanoparticles?Ge NPs?,as a member of Group ? semiconductor nanomaterials,also have the advantages of good biocompatibility,low toxicity,high chemical stability and size-dependent fluorescence properties.In recent years,it has attracted significant attention of more and more researchers.At present,there are still some disadvantages of the synthesis of Ge NPs,such as cumbersome experiments,harsh conditions and tedious time.In addition,the application of Ge NPs mainly focuses on the field of lithium-ion batteries and optoelectronic devices.There are few applications on the fluorescence properties of Ge NPs,and the research of its luminescence mechanism is still not deep and comprehensive enough.Therefore,developing new preparation methods and exploring unknown merits of Ge NPs are extremely important to extend the application of Ge NPs.In this thesis,after summarize the synthesis,properties and applications of Ge NPs,we have developed a one-step approach for the synthesis of Ge NPs and explored its new properties and application.The main works are as follows:1.We developed a facile one-step route for preparing fluorescent and water dispersed Ge NPs by utilizing organogermanes as the precursor,operated at mild reactive conditions.The as-synthesized Ge NPs have an average diameter of 2.6±0.5 nm and intense blue-green fluorescence.The morphology and structure of Ge NPs were characterized by a series of characterization methods,and the synthesis mechanism was discussed.Furthermore,the as-synthesized Ge NPs show remarkable water dispersibility,favorable biocompatibility,outstanding photostability,excellent storage stability and low cytotoxicity.More importantly,these Ge NPs can act as satisfactory fluorescence probe and successfully be applied to cellular imaging of HeLa.Compared with traditional methods,this method not only has the advantages of mild reactive conditions and simple experimental operation,but also avoids further surface modification process.2.We discovered that Ge NPs have the intrinsic peroxidase-like catalytic activity and can significantly accelerate the oxidation of 3,3,5,5-tetramethylbenzidine?TMB?by H₂O₂ for the first time.Compared with natural enzyme?horseradish peroxidase,HRP?,Ge NPs maintain higher catalytic stability after treatment at different pH,temperature and ionic strength.Furthermore,a Ge NPs-based colorimetric platform was established to detect biomolecules with favourable sensitivity and selectivity,such as uric acid,glucose and choline.This work finds the new property of Ge NPs and extends its application in biosensing.3.We synthesized a series of uniform-sized Ge NPs terminated with different ligands by chemical reduction method.Fluorescence spectra show that the emission of Ge NPs can be tuned from blue to yellow-green by altering the ligands.The theoretical and experimental studies have shown that the degree of conjugation of ligands has a crucial influence on their fluorescence,and the law of fluorescence regulation was discussed in depth.The present study offers a simple and feasible strategy for tuning the fluorescence properties of Ge NPs.