Fabrication Of Multi-functional Carbon Quantum Dots And Their Applications In Biomedical Fields

Objective:In this study,two novel carbon quantum dots with different functions were prepared and applied to biological antioxidant and gene delivery.Cell phagocytic,antioxidant and photothermal conversion functions of cerium doped carbon quantum dots(Ce-doped CDs)had been explored after characterization of.physical,chemical and optical properties.At the same time,after the initial characterization of amino-carbon quantum dot(N-doped CDs),the feasibility as gene carriers in mediating Cp G oligonucleotide transfer was studied,and its potential value in the combination of photothermal and immunotherapy in tumor was discussed.Methods:1.Cerium doped carbon quantum dot(Ce-doped CDs)was prepared by microwave-assisted hydrothermal carbonization using cerium oxalate as precursor and glycine as surface passivation agent.2.The physical properties of Ce-doped CDs was characterized by high power transmission electron microscopy(HRTEM)and X-ray diffraction(XRD).The chemical properties of ce-doped CDs were characterized by Fourier transform infrared spectroscopy(FTIR)and X-ray photoelectron spectroscopy(XPS).The optical properties of Ce-doped CDs were characterized by UV-Vis and PL spectra.3.The biocompatibility of Ce-doped CDs was detected by CCK-8 experiment.In addition,the process and location of Ce-doped CDs entering cells were monitored by laser scanning confocal microscope.4.The scavenging effect of Ce-doped CDs on hydroxyl radicals was studied by using anti-methyl violet(MV)fading experiment and electron spin resonance(ESR).At the same time,the antioxidant function of Ce-doped CDs was investigated by CCK-8 experiment and live-dead cell staining experiment.5.The photothermal conversion capacity and photothermal tumor killing capacity of Ce-doped CDs were investigated by irradiating the Ce-doped CDs solution and co-incubated cells with 808 nm near infrared(NIR).6.The carbon quantum dot(N-doped CDs)with gene carring function was synthesized from glucose and PEI,and its gene-loaded function was verified by gel block test.Result:1.Carbon quantum dots with dark brown powders were prepared and doped with cerium to form Ce-doped CDs.2.The Ce-doped CDs prepared was small in size,with particle size of only 2.6 nm,in accordance with gaussian normal distribution,and has lattice and non-lattice mixed phase structure.Ce-doped CDs consisted of carbon,nitrogen,oxygen and cerium,and its surface was rich in hydrophilic groups such as-COOH and-OH,which made it have good water dispersion.Ce-doped CDs had photoluminescence property,showing bright blue-green under ultraviolet light.3.After co-incubation with the cells for 2 days,the cell activity remained above 95 %under a concentration of up to 800 ?g/m L.Laser scanning confocal microscopy showed that Ce-doped CDs rapidly entered the cell and located in the cytoplasm,but did not enter the nucleus.The results showed that Ce-doped CDs had good biocompatibility.4.Ce-doped CDs could weaken the fading reaction of H2O2-mediated MV,appease the wavelength of ESR at a specific position subside,and reduce cell apoptosis,so it had been preliminarily demonstrated that ce-doped CDs has antioxidant function.5.Ce-doped CDs reached 55.1 ? at 6 min under the irradiation of 1.0 W/cm2 power density under 808 nm near-infrared light with a concentration of 200 ?g/m L,and could be repeated photothermal treatment without affecting its photothermal conversion performance.What's more,Ce-doped CDs was incubated with tumor cells,and the concentration of Ce-doped CDs was positively correlated with cell apoptosis after 808 nm NIR irradiation.It had been proved that Ce-doped CDs had superior photothermal conversion ability and could be used to inhibit tumor growth.6.Gel block test showed that as the ratio of N-doped CDs/sh Fox M1 minicycle plasmid gradually increased,the strips shown by agarose gel electrophoresis gradually remained in the sample holes,and some even moved towards the negative electrode.The result showed that N-doped CDs could be assembled with gene and block its movement in swimming lanes.Conclusion:1.Ce-doped CDs have excellent biocompatibility,photoluminescence and easy to be phagocytosis by cells,as well as good antioxidant capacity and photothermal conversion function.2.N-doped CDs have excellent gene-loaded function,which lays a solid foundation for the next step of immunity and photothermal treatment.