The Study Of Carbon Dots: Interaction With Fluorescein Isothiocyanate,Selective Cell Imaging And Their Antiviral Activity

Carbon dots(CDs),a new type of fluorescent nanoparticles,have attracted considerable attention due to their distinct optical properties and high biocompatibility,which have been widely used in biochemical detection,bioimaging,vivo diagnosis and treatment.The study on CDs-based ratiometric fluorescent sensor and antiviral study has great potential.In view of this,the interactions between CDs and fluorescein isothiocyanate(FITC)was studied.Additionally,the application of CDs in cell imaging and antiviral activity was explored.Here,the main contents of this paper are as follows:1.The effect of FITC on CDs was explored by spectroscopic techniques at pH 5.1,7.0 and 9.0.The fluorescent intensity of CDs was found to be quenched gradually after mixing directly with different concentrations of FITC,but the fluorescent lifetime of CDs remained unchanged.According to the results of UV-vis absorption spectra and fluorescent lifetime measurements,a pH-dependent inner filter effect(IFE)between CDs and FITC was proposed.However,the fluorescent lifetime of CDs deceased after their conjugation with FITC,implying the fluorescence resonance energy transfer(FRET)between CDs and FITC.This study has revealed two different effects of FITC on CDs with varying pH values and provided useful theoretical guidelines for further research on the interaction between other nanoparticles and fluorophores.2.A facile strategy was developed to prepare two types of CDs capable of selective entrance into cytoplasm and the whole cell without further surface modification.The surface charge of CDs changes from negative to neutral after the addition of urea in the hydrothermal process,and the as-prepared CDs exhibit different fluorescent colors.The blue-fluorescent CDs(b-CDs)can only enter the cytoplasm,while the cyan-fluorescent CDs(c-CDs)can distribute over the whole cell,including nucleus.Additionally,the antiviral activity of the two CDs against pseudorabies virus(PRV)was studied and b-CDs were shown to have better antiviral activity.This study has provided a facile and novel strategy for fabrication of CDs used in selective cell imaging,which may facilitate the application of CDs in nanomedicine.