Qi Xiao

Carbon dots (CDs) have attracted great attention in the field of materials science and biology. In this paper, three kinds of CDs with different doping elements were synthesized by one-step hydrothermal method. The binding modes and binding capacities of ctDNA and carbon dots doped with three different elements were systematically studied by means of multispectral method, melt chain temperature method and viscosity method. Fluorescence experiments have proved that the interaction modes of CDs, N-CDs and N,S-CDs with ctDNA were groove binding, and the binding force was mainly hydrogen bond and van der Waals interaction, accompanied by slight electrostatic force. In the presence of strong electrolytes and denaturants, the groove binding between carbon dots and DNA was weakened. Circular dichroic spectroscopy and FTIR spectroscopy showed that the groove binding of carbon dots and DNA did not significantly change the conformation of DNA. It was worth noting that compared with undoped carbon dots (CDs), doping with nitrogen and sulfur could weaken the groove binding ability of N,S-CDs and ctDNA. However, increasing the surface charge of carbon points could enhance the binding of N-CDs to ctDNA. This conclusion is expected to provide a theoretical reference for the design of targeted carbon dots in the biomedical field in the future.