Zwitterionic Coating Promotes Zinc Oxide Quantum Dot Stability and Reduces Aggregation in Biological Media

Bio-compatible, non-toxic and low-cost ZnO quantum dots (QDs) have been widely used in biological field. However, their instability in biological media limits their application greatly. Thus it is of great importance to improve their stability. In this study, water-soluble ZnO quantum dots were synthesized utilizing zwitterion ligand to resist aggregation in biological media. Results showed that the zwitterion coated ZnO QDs can be stable both under harsh salt condition and in serum for at least 30 days while maintaining part of its fluorescence intensity. This work provides a kind of excellent stable ZnO QDs with potential application in vivo.