Large-pore mesoporous silica: template design, thin film preparation and biomolecules infiltration

Abstract

Nanopores have been applied in the development of artificial biocatalytic systems, controlled drug delivery, and solid-state sensing devices. The interaction of biomacromolecules with surfaces show a dependence on the nanopore diameter, crucial in their ability to infiltrate porous materials. In this context, ordered mesoporous materials obtained by evaporation-induced self-assembly are model materials to test pore-biomolecule interactions. Nevertheless, these materials are generally restricted to pore diameters within the 2-10 nm range, therefore, new polymers as templating agents hold potential to provide an easy reproducible route for the synthesis of mesoporous silica thin films (MTF) with pore diameters above 10 nm without the use of swelling or additional structuring agents. Here, we present a novel and simple approach towards large pore MTF through the combination of supramolecular templating and phase separation with tailor-made block co-polymers. Accurate tuning of the oxide pore size distribution (with small mesopores between 13-18 nm diameter) is achieved by controlling the length and the nature of the hydrophilic polymer block used as a template through a simple reversible addition-fragmentation chain transfer (RAFT) polymerization approach. The importance of these features is highlighted by showing the capability that these new materials offer for biomolecule infiltration benchmarked against the widespread MTF prepared using pluronic F127 as a template. Effect of protein to pore diameter ratio, protein location and effect of pH and ionic strength is briefly tested and discussed.