Fluorescent Silicon Nanomaterials:from Synthesis,Functionalization,to Optical Application

Recently,silicon nanomaterials featuring unique optical,electrical properties and low toxicity have drawn great attention,which are intensively exploited for various applications in optoelectronic device,bioimaging,cancer therapy and electrocatalysis fields.However,due to the limitation of synthetic and functionalized strategies,several issues(e.g.,low photoluminescence quantum yield(PLQY)and relatively tedious functionalized procedures)need to be further addressed.Therefore,it is still in high demand to design fluorescent silicon nanomaterials with designable functional properties.Herein,we design novel kinds of fluorescent silicon nanomaterials through metal ions doping and organic ligands modification.Moreover,we further demonstrate their application in optical information encryption and biosensor fields.Corresponding research content mainly includes:(1)Transition-metal ions-doped silicon nanomaterials with optical and magnetic properties is synthesized through metal ions-induced anisotropic growth under microwave irradiation.The resultant silicon nanomaterials are further explored for multi-color bioinaging and infonnation encryption.(2)A kind of dual-emission fluorescent silicon nanomaterials.which is made of europium-doped silicon nanopartieles,is developed.The resultant silicon nanomaterials are efficacy for the detection of intracellular temperature with high accuracy.(3)Triple-emission fluorescent silicon nanoparticles(SiNPs)are obtained through surface modification of functional organic ligands.The prepared SiNPs are further exploited for the detection of metal ions and white light-emitting diode applicationsThe nain research strategies and results are briefly demonstrated as followsChapter 1:We first give a brief introduction of fluorescent silicon nanomaterials and their recent progresses in synthetic strategies.Then,we summarize representative methods for functionalizing the fluorescent silicon nanomaterials.Afterwards,we illustrate typical examples of fluorescent silicon nanomaterials-based bioimaging and biosensor applications.We further discuss challenges and opportunities in the preparation and application of fluorescent silicon nanomaterials.Finally,we provide an overview of proposal significance and novelty of our current researchChapter 2:A kind of shuttle-liked one-dimensional silicon nanomaterials(SiNSs)is prepared through metal ions-indued anisotropic growth of silicon under microwave irradiation.The resultant SiNSs simultaneously exhibit strong fluorescence(PLQY:?15%),robust photostability(i.e.,preserve?80%of the initial intensity after 12-h continuous UV irradiation)and distinct magnetism(paramagnetism at room temperature and ferromagnetism at low temperature).Significantly,the prepared SiNSs feature excitation wavelength dependent emission(from?450 nm to?560 nm under serial excitation wavelengths from 390 nm to 520 nm).Taking advantages of unique optical and magnetic properties,we explore the SiNSs as fluorescent probes or anti-counterfeiting ink for multi-color bioimaging or dual-mode infomation encryption in a long-term manner,respectivelyChapter 3:Taking advantages of the unique optical properties of silicon nanoparticles(SiNPs)and rare earth metals,a kind of europium(Eu3+)-doped silicon nanoparticles(Eu@SiNPs)is presented,which could exhibit dual-emission fluorescence(blue(455 nm)and red(620 nm)emission).The reason is that the Eu3+ ions can be efficiently sensitized by SiNPs through a Dexter energy transfer mechanism.In particular,the presented Eu@SiNPs feature low toxicity(cell viability of treated cells remains above 90%during 24-h treatment)and robust photostability.More significantly,the fluorescence intensity of Eu@SiNPs exhibits a linear ratiometric temperature response in a broad range from 25? to 70?.Taking advantages of these attractive merits,such Eu@SiNPs-based nanothermometer is able to accurately(?1.5%change/?)determine dynamic changes of temperature in real-time and long-term(e.g.,30 min)mannersChapter 4:We develop a new strategy for the synthesis and functionalization of SiNPs with triple-emission properties.Firstly,we prepare a series of derivatives of boron dipyrromethene(BODIPY)with ester groups,which serve as functional ligands to modify the surface of SiNPs(SiNPs-L).The as-prepared SiNPs-L display triple-emission(emission wavelengths:?450 nm,?520 nm and?650 nm)fluorescent properties.We further explore the mechanism of the unique fluorescent properties of SiNPs-L.Moreover,we investigate the relationship between the polarity of ligands and optical properties of SiNPs-L.Taking advantages of these attractive merits,the as-prepared SiNPs-L are exploited as fluorescent probes or color converter for the detection of metal ions or the construction of white light-emitting diode,respetivelyIn summary,in this thesis,we demonstrate that one-dimensional SiNSs featuring fluorescent and magnetic properties are prepared through transition-metal ions doping The Eu@SiNPs with temperature dependent dual-emission properties are synthesized through rare earth metal ions doping.The SiNPs-L with triple-emission are obtained through BODIPY ligands modification.Taking advantages of their attractive properties,these resultant functional silicon nanomaterials are exploited for multi-color bioimaging,information encryption,nanothenmometer,detection of metal ions and white light-emitting diode applications.Our research provides valuable information for designing functional silicon nanomaterials,facilitating the promotion of fluorescent silicon nanomaterials-based widespread applications.