Research On Synthesis Of Strong Fluorescent Carbon Nanomaterials And Targeted Imaging Of Cell,Subcellular Organelle

Carbon dots(CDs)was a carbon-based zero-dimensional material,compared with traditional semiconductor quantum dots and organic fluorescent dyes,CDs process stable fluorescence,strong photobleaching resistance,good water solubility,low toxicity,environmental friendliness,wide source of raw materials,low cost,outstanding biocompatibility,simple surface modification and many other advantages.And it is widely used in biological detection,biological imaging and labeling and many other research fields.The fluorescence quantum yield(FLQY)of some carbon dots used for imaging and labeling is low(?10%),the functionalization process of carbon dots is complicated and tedious.These problems greatly limit the practical application of carbon dots.This paper detailedly investigates the current synthesis of CDs and their imaging applications in cells and subcellular organelles,combined with the current status of targeted imaging probes in cells and sub-organelles.Aimed at developing fluorescent CDs with highly fluorescence quantum yields,we explore some simple and efficient functional carbon dot synthesis,and its imaging applications in cells or subcellular organelles.Mainly carry out the following two aspects:(1)The lysosome is a waste treatment system of the cell and participates in many life processes.The lysosomal dysfunction will cause many diseases.The development of efficient and specific lysosomal visualization probes is of great significance for understanding lysosomal related diseases.In view of the fact that currently commercial lysosomal probes are easily photobleached and biodegradable,the toxicity of traditional semiconductor quantum dot probes cannot be ignored.We explored the commercial acquired rose bengal with heavy atom and amino-rich polyethyleneimine as raw materials,and one-step synthesis of ultra-bright,intrinsically targeted carbon dots(P-R CDs)by hydrothermal method.The experimental results show that the fluorescence of P-R CDs is stable,the absolute fluorescence quantum yield is as high as 90.49%,and the phototoxicity and dark toxicity are very low;without any post-surface modification,it has the ability to target lysosomes for long-term imaging;XPS and FTIR proved that de-heavy atom effect and a large number of amino groups on the surface of the carbon dot;dehalogenation crosslinking and structural reorganization limit intersystem crossing and non-radiative transition and greatly improve the FLQY of the carbon dots,reduce the yield of singlet oxygen and toxicity of the material biological application;at the same time,the excellent surface structure of the carbonized recombinant material allows it to target acidic microenvironment lysosomes and accumulate in the lysosomes for long-term targeted imaging of lysosomes.This work provides a strategy for the rapid preparation of ultra-bright functional carbon dots,which lays the foundation for the development of subcellular imaging carbon dots probes.(2)Cancer cell targeted imaging functional probes are of great significance for the visualization of cancer cells.The surface groups of carbon dots may be inherited from synthetic raw materials,at the same time,surface groups will affect their fluorescence efficiency.Using folic acid with cancer cell targeting ability and arginine with nucleating as raw material,we propose to explore one-step hydrothermal synthesis of carbon dots(F-CDs)via the surface auxiliary effect of Tris.We also explore the ability of F-CDs to target and image cancer cells.The carbon dots are obtained through optimization of different raw material combinations,the experimental results show that the carbon points with the best fluorescence performance will be obtained when folic acid,arginine,and Tris are hydrothermally carbonized at the same time.Compared with the control group without Tris,the fluorescence intensity and fluorescence quantum yield of F-CDs have been improved.XPS and FTIR experimental data show that F-CDs have a large number of amino groups,it is important that the surface hydroxyl content increases significantly,indicating that the high content of N atoms doping and the structure of Tris are indispensable for constructing strong fluorescent functional carbon dots.Cell imaging experiments have shown that F-CDs have excellent biocompatibility.Under the combined effect of folic acid-mediated recognition and endocytosis pathway,CDs can specifically target cancer cells for imaging.The results of this experimental work and the exploration of related mechanisms have laid the foundation for the preparation of strong fluorescent carbon materials with cancer cell targeting.