Integrated Carbon Quantum Dots For Cancer Cell Targeted Fluorescence Imaging And Gene Therapy

In this paper,a novel delivery system with functions of tumor targeting fluorescent imaging and gene delivery was developed for the diagnosis and treatment of tumors.Herein,carbon quantum dots?CDs?were selected as the core of carrier,providing the function of the fluorescence imaging.The positive charge density of branched polyethyleneimine?bPEI,1000Da?grafted on CDs can combine with DNA and promote endosome escape by"proton sponge"for gene delivery.The cell membranes which coated the CDs provided the targeted ability to tumors.1.Synthesis and characterization of CDs and CDs-PEI.The CDs were synthesized using urea and citric acid by microwave synthesis,and the morphology of the CDs was characterized by TEM,which showed that the particle size of CDs was about 5 nm and dispersed uniformly.FTIR result showed that CDs are rich in carboxyl?-COOH?.The UV-vis absorption displayed a clear band at 411 nm.The photoluminescence?PL?spectra demonstrated a strongest fluorescence emission at 535 nm under 460 nm excitation.CDs bond with PEI by acylation reaction,making CDs-PEI surface with positive charge,could compress DNA effectively.TEM result showed that the CDs-PEI diameter was about 10 nm.FTIR result revealed that there are amide?-CO-NH-?and amino group?NH₂?on CDs-PEI.The DLS results showed that the zeta potential of CDs was increased from-16.5 mV to 24 mV after reaction with PEI.The UV-vis absorption of CDs-PEI showed a clear band at335 nm.The PL spectra showed a strongest fluorescence emission at 456 nm under 370 nm excitation.Buffer capacity test showed that CDs-PEI has good proton buffer capacity.2.Performance study of CDs-PEI/pDNA and CDs-PEI/pDNA/M complex.Particle size of CDs-PEI/pDNA complexes with different N/P were were between200-500 nm determined by DLS and zeta potential were between 4-30 mV.After coating Hep-G2 cell membranes,CDs-PEI/pDNA/M complex particle size were between 130-450 nm;zeta potential were between 20-17 mV.Gel retardation experiment proved that the carrier CDs-PEI and CDs-PEI/M can combine with pDNA in vitro by electrostatic interaction,and can effectively protect pDNA from degradation by DNase I and serum,achieving successful gene delivery.MTT results showed that CDs-PEI/M displayed low cytotoxicity compared with PEI and CDs-PEI,because homologous cell membranes blocked the excess positive charge.Transfection experiments with pDsRed2-N1 as reporter gene in vitro demonstrated that the CDs-PEI and CDs-PEI/M had the highest transfection efficiency at N/P ratio of 12.8.After introduction of therapeutic genes p53 and TRAIL,CDs-PEI/p53 and CDs-PEI/TRAIL could induce apoptosis effectively than that of Lipofectamine 2000/p53 and Lipofectamine2000/TRAIL.3.Investigation on the target ability of CDs-PEI/pDNA/M.Three cell lines?MCF-7,Hela and Hep-G2?were selected to study the uptake of nanoparticles with different cell membranes coating,and the results showed that the cells have the highest intake of CDs-PEI with homologous membranes coating.In vitro transfection experiments showed that the transfection efficiency of the CDs-PEI/pDsRed2-N1/M system with MCF-7,Hela and Hep-G2 cell membranes coating were the highest in the group of their homologous cells.The cell apoptosis experiments of p53 and TRAIL showed that the system with homologous membrane coating induced itself cell apoptosis most efficiently.