Synthesis of water dispersible and biocompatible nanodiamond composite via photocatalytic surface grafting of zwitterionic polymers for intracellular delivery of DOX

As a member of nano-carbon compound, nanodiamonds (ND) with diverse structure, small size and relative low toxicity has been extensively explored for different applications especially as delivery vehicles for drugs. However, surface functionalization of ND with polymers is still required to overcome their poor water dispersibility and improve drug delivery performance. In this work, we reported a simple photocatalytic atom transfer radical polymerization (ATRP) method for surface functionalization of ND by using FeBr3 as the photoredox catalyst. Owing to the introduction of water dispersible 2-methacryloyloxyethyl phosphorylcholine (MPC), resultant NDs-MPC displayed improved water dispersibility and low toxicity. The anticancer agent DOX could be loaded on NDs-MPC efficiently and controlled release from ND-P-DOX complexes. The cell viability and cell imaging results demonstrated that DOX can be transported into cells and maintained its corresponding therapeutic effect. More importantly, as compared with traditional ATRP, photocatalytic ATRP could not only operate under rather mild conditions but also could avoid utilization of expensive and toxic agents. Considered the advantages of photocatalytic ATRP and ND, the method developed in this work could be a promising strategy for fabrication of multifunctional ND-based composites for different applications.