Silica-assisted incorporation of polydopamine into the framework of porous nanocarriers by a facile one-pot synthesis.

Mussel-inspired polydopamine (PDA), with its advanced bio-adhesive properties, has shown great potential in drug delivery based on host-guest interaction. However, it is difficult to synthesize PDA NPs of high surface area using the traditional polymerization of dopamine monomers in an alkaline solution. Taking advantage of the interaction between PDA and silicic acid inspired by biosilicification, PDA was rendered with high surface area in 70 nm-sized hybrid porous particles by a silica assisted one-pot preparation. PDA building blocks were successfully incorporated into the silica framework by controlled addition of dopamine (1.25-5 mol% with respect to the silica source) in a typical synthesis of mesoporous silica nanoparticles (MSNs). It is revealed that the cooperative molecular interaction between silicic acid and catechol groups of PDA results in a retardation of the silica condensation during the particle formation process. Moreover, the replacement of dopamine with polyphenols such as epigallocatechin gallate (EGCG) or tannic acid (TA) resulted in complete phase separation of the polymer and silica at the same molar ratio, suggesting the important role of amines in PDA towards stable hybridization in the particles. The application potential of the PDA-MSN hybrid nanocarriers is demonstrated by an unprecedentedly high drug (DOX) loading capacity of 1000 mg g, a sustained drug release, as well as enhanced killing efficiency of cancer cells at low dosage. These findings are expected to inspire strategies and pave a way for utilizing PDA for constructing organic-inorganic composite nanocarriers.