(362c) Bio-Inspired Nanomaterials for Controlled Release

Bio-inspired nanomaterials for controlled release

Chun-Xia Zhao*, David Wibowo and Anton P.J. Middelberg

Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, St Lucia QLD 4072, Australia.

*Oral presentation and corresponding: z.chunxia@uq.edu.au

Abstract

Engineered nanomaterials have attracted significant research interest during the past decades for various applications. While compared to man-made materials, precision nanomaterials inspired by nature promise to revolutionize many sectors including photonics, coatings, healthcare because of their sophisticated structure. In this talk, I will introduce two different types of bio-inspired nanomaterials for controlled release, 1) oil-core silica nanocapsules for sustained release and 2) core-shell silica nanoparticles for triggered release. Biocompatible silica nanocapsules were developed in our lab using a patented technology - the emulsion and biomimetic dual-templating platform technology. This technology is based on the novel design of bifunctional peptides or proteins (acting as not only biosurfactants but also biomineralizing agents) by modularizing a partial sequence encoding surface activity with a series of amino acids having biosilicification ability. Nanoemulsions were formed in the presence of these bifunctional biomolecules as a result of their surface activity, then a silica precursor such as tetraethyl orthosilicate was added to initiate the biosilicification induced by the catalytic peptide sequence. Oil-core silica nanocapsules were produced under mild conditions, including room temperature, neutral pH and without use of any toxic chemicals. We also demonstrated the facile loading of actives by directly dissolving them in the oil phase, followed by emulsification and biosilicification. Slow release of hydrophobic ingredients encapsulated in the oil phase can be controlled by tuning the shell thickness of the silica nanocapsules. This technology opens a new facile and environmentally friendly strategy for fabricating capsules that are potentially applicable various fields. In the other hand, we developed silica-core and hydroxyapatite shell nanocomposites through a biomimetic mineralization process. The multifunctional nanocomposites composed of a magnetite nanocrystal core and a mesoporous silica shell (Fe₃O₄@mSiO₂) end capped with pH stimuli-responsive hydroxyapatite (HAP) nanovalves. The natural nontoxic component hydroxyapatite cap system allows the pH-responsive release of loaded drugs within acidifying intracellular compartments such as endosomes and lysosomes at specific targets. The mineral coated Fe₃O₄@mSiO₂ nanocomposites provide efficient pH-responsive nanocarriers for potential applications in simultaneous bioimaging, targeting and pH-responsive release.