No abstract

The preparation of alkyl chain-grafted poly(l-lysine) (PLL) vesicles with tunable molecular assembly in aqueous solution and the evaluation of their membrane permeability by drug release experiments have been investigated. Upon grafting long alkyl chains, polypeptides confined in the assembled nanostructures adopted ordered conformations such as α-helices or β-sheets/turns, leading to the dense packing of membranes and, consequently, the decreases in vesicular size and membrane permeability. The vesicles can also be cross-linked by genipin to form stable structures with tunable membrane permeability. Additionally, these vesicles exhibited noticeable pH-sensitive behavior, depending on the grafted alkyl chain and cross-linking.

A simple and versatile approach is proposed to use cross-linked polypeptide hydrogels as templates for silica mineralization, allowing the synthesis of polypeptide-silica hybrid hydrogels and mesoporous silica (meso-SiO(2)) by subsequent calcination. The experimental data revealed that the cross-linked polypeptide hydrogels comprised of interconnected, membranous network served as templates for the high-fidelity transcription of silica replicas spanning from nanoscale to microscale, resulting in hybrid network comprised of interpenetrated polypeptide nanodomains and silica. The mechanical properties of these as-prepared polypeptide-silica hybrid hydrogels were found to vary with polypeptide chain length and composition. The synergy between cross-link, hydrophobic interaction, and silica deposition can lead to the enhancement of their mechanical properties. The polypeptide-silica hybrid hydrogel with polypeptide and silica content as low as 1.1 wt% can achieve 114 kN/m(2) of compressive strength. By removing the polypeptide nanodomains, mesoporous silicas with average pore sizes ranged between 2 nm and 6 nm can be obtained, depending on polypeptide chain length and composition. The polypeptide-silica hybrid hydrogels demonstrated good cell compatibility and can support cell attachment/proliferation. With the versatility of polymer chemistry and feasibility of amine-catalyzed sol-gel chemistry, the present method is facile for the synthesis of green nanocomposites and biomaterials.

Alkyl chain-grafted poly(l-lysine) vesicles with tunable molecular assembly were prepared by varying the polypeptide chain length and grafted alkyl chains.