Ovalbumin as a Precursor for Green Synthesis of Highly Fluorescent Carbon Dots for Cell Imaging

One-pot green synthesis of highly fluorescent carbon dots (CDs) was developed by hydrothermal treatments of ovalbumin (OVA) from hen eggs. The hydrothermal treatment time, temperature, OVA concentration and pH value as the effective factors on the light emissions of the CDs were optimized. The optical and structural characteristics of the CDs were confirmed with UV, FL, FTIR, Raman, XPS, XRD, HRTEM and AFM. The quantum yield was up to 34.5%, and the CDs were small in size (2.51 nm) with an excellent water solubility. The CDs also exhibited excellent pH and salt stability, suggesting that they can be used under harsh environmental conditions. The MTT assay of mouse osteoblast and macrophage cells line showed CDs had extremely low cytotoxicity. In addition, the in vitro imaging study revealed the CDs had an excellent optical property as well as biocompatibility and thus could be used as a superior fluorescent bioimaging agent. In conclusion, a highly photoluminescent CDs with high solubility, excellent pH and salt stability and low cytotoxicity were synthesized with OVA as a natural precursor. The photoluminescent CDs showed an excellent optical property as well as biocompatibility and thus have a great potential for biomedical applications in the future.