Prepareation Of Carbon Dots And Carbon Dot-based Composites And Their Bioimaging Application

Carbon dots have been widely used in bioimaging, ion detection and photoelectronic applications due to their high fluorescent intensity, good photostability, biocompatibility and easy surface modification. However, there are some limitations of carbon dots in bioimaging application because their excitation light is always UV light. In particular, it is still at the early stage to utilize carbon dots to study the mechanism and the movement of nanoparticles during the cell penetration. Therefore, it is of great importance to fabricate carbon dots to meet the above-mentioned requirements. In this paper, two kinds of carbon dot related nanomaterials were fabricated, that is, carbon dots with good two-photon fluorescence property synthesized by hydrothermal method and carbon dot-based nanocomposites prepared by one-step reduction method. FTIR, XRD, TGA and XPS analysis were employed to analyze the structure and composition of the two nanomaterials. UV-vis and one/two-photon fluorescence instruments were adopted to characterize their optical properties.The fluorescent stability was also evaluated. The results showed that the carbon dots had good dispersibility in water, excellent one and two photon fluorescence, similar solid state fluorescence to HPAA, very low cell toxicity and could be successfully applied in cellular imaging. The particle size and the optical properties of the carbon dot-gold nanocomposites were determined by the raw material ratio. The particle size of nanocomposites would have narrow distribution around 2 nm and have similar fluorescent properties with carbon dots in the condition that the mass ratio of carbon dots to chloroauric acid was 3:1. Using MTT method, the toxicity of the two nanomaterials were investigated. Finally, the two-photon fluorescence and the two-mode cellular imaging application for the nanocomposites were implemented respectively.