Application Of Fluorescent Carbon Nitride Quantum Dots In Ion Detection,bioimaging And Fingerprint Development

Quantum dots(QDs)are usually composed of ???,??? or ??? elements with a size of 2?10 nm As a nanoscale semiconductor material,QDs exhibit many excellent optical properties,such as adjustable illuminating color,high fluorescence quantum yield,stable fluorescence and long fluorescence lifetime.Carbon nitride quantum dots(CNQDs)are kind of novel fluorescent nanomaterials composed of non-metal C and N elements in a two-dimensional planar structure.Compared with traditional semiconductor quantum dots(CdTe or CdS),CNQDs have excellent chemical stability,photostability and biocompatibility.Studies have shown that CNQDs have broad application prospects in the fields of sensing and biology in recent years.In this thesis,based on the excellent fluorescence properties of CNQDs,fluorescent CNQDs are applied in sensing analysis and imaging research,which consists of three parts:mercury ion detection,biological imaging and fingerprint development.The main research contents are as follows:(1)A fluorescence sensor based on DTG-CNQDs was constructed.First,CNQDs were prepared by a low-temperature solid-phase method,and then DTG-CNQDs were obtained by modifying DTG on the surface of CNQDs.Under the excitation of ultraviolet light(365 nm),DTG-CNQDs emit bright blue fluorescence with a quantum yield of 27%.Because of the strong affinity between Hg2+and DTG-CNQDs,the presence of Hg2+can quench DTG-CNQDs fluorescence.The experimental results show that this fluorescence sensor has good selectivity with the linear range of 0.020?0.50 ?M and detection limit of 0.63 nM.In addition,the sensor can be successfully applied to the detection of Hg2+in real water samples,which provides a fast and sensitive analytical method for monitoring Hg2+in water samples(2)The application of CNQDs in vivo imaging was explored.The model organism C.elegans were taken as a research object.According to the changes in physiological indicators(body length,swallowing rate,egg production,life span,head swing frequency and body swing frequency)of C.elegans after exposure of CNQDs for 24 h,the toxicity induced by CNQDs in C.elegans was investigated for the first time.The experimental results showed that CNQDs have good biocompatibility and low toxicity.What's more,the fluorescence imaging of CNQDs in C.elegans was preliminarily explored,which proved that CNQDs can be used as a fluorescent probe for biological imaging.This experiment provides research ideas for evaluating the toxicity of nanomaterials and fluorescent probes in the future,and it is worthwhile to further explore the toxicological mechanism.(3)The application of CNQDs in vitro imaging,namely the development of latent fingerprints,was explored.Based on the solid-state luminescence of CNQDs,CNQDs were combined with fingerprints by powder brushing.The combined fingerprints emit bright blue fluorescence under the illumination of a multi-band source(320?400 nm).This experiment mainly explores the development effect of CNQDs on the fingerprints of four different bearing objects of glass,aluminum sheet,plastic and paper.We also explore the development effect of CNQDs on aging fingerprints of plastics and aluminum objects.The experimental results show that the CNQDs prepared in this experiment have a good development effect on the latent fingerprints of plastic and aluminum objects.The acquired fingerprint images are clearly visible and the fingerprint details are rich,including secondary and tertiary feature information This study provides a reliable visualization method for the acquisition of latent fingerprints in practical applications,which has a high identification value.