Biomineralization of mesoporous silica and metal nanoparticle/mesoporous silica nanohybrids by chemo-enzymatically prepared peptides

We report the feasibility of using chemo-enzymatically prepared peptides, oligo(L-lysine-co-L-tyrosine) (oligoKY) and oligo(L-lysine-co-L-phenylalanine) (oligoKF) for sequentially mediated growth of metal nanoparticles (NPs) and/or silica mineralization. This approach is easy to handle, environmentally benign, and economical as compared to other tedious and multiple-step peptide synthesis approaches. Colloidal stable silica/peptide particles with various sizes between 150 and 430 nm can be simply fabricated by tuning silica precursor concentration via peptide-mediated silica mineralization. Mesoporous silica with pore sizes mostly between 2 and 8 nm can be obtained by replication of sheet-like peptide nano-assemblies. In addition, Au NP/silica and Ag NP/silica nanohybrids can be prepared by peptide-mediated nucleation of metal NPs onto silica/peptide colloidal particles. Silver/palladium (AgPd) alloy-based silica nanohybrids were also prepared via galvanic replacement reaction. The experimental data revealed that these nanohybrids showed reliable and enhanced catalytic activities in reducing 4-nitrophenol, which are primarily dictated by the surface area/size of metal NPs and the accessibility to metal NPs, as well as the mass transfer of chemicals in the porous network. This study demonstrated that chemo-enzymatic polymerization is a promising approach to design peptide materials with designated building blocks for specific applications.