Biomineralization is a process during which mineral clusters and biomacromoecules self-assemble into nanostructured composite materials. Proteins play multiple roles in these hybrid materials, as templating agents to guide self-assembly and control the properties of the material, and as ligands for biological interactions. With this in mind, we developed a method to self-assemble porous protein-inorganic supraparticles containing functional enzymes. We first constructed a recombinant tri-block fusion protein that contains an alanylglycine-rich random coil midblock flanked by leucine zipper coiled-coil domains. The midblock is thought to interact with the inorganic component, calcium phosphate, and enzyme incorporation can be achieved post-assembly by non-covalent conjugation via high affinity interaction between zippers. The engineered fusion protein directs formation of flower-like nanohybrids that are further self-organized into porous supraparticles. When calcium phosphate precipitates in the presence of the fusion protein, it provides nucleation sites and directs the growth of calcium phosphate petals into protein-inorganic “nanoflowers”. The nanoflowers themselves self-assemble via high valency interactions in combination with interfacial adsorption and compression, packing into hierarchically structured and porous micron-scale supraparticles. The protein-inorganic supraparticles provide a large surface to immobilize proteins fused with leucine zippers for high-affinity conjugation by incubation in aqueous solution. Immobilization of enzymes can enhance their stability and catalytic activity, thus providing benefits for many applications. We demonstrate both therapeutic and biocatalysis uses of the supraparticles containing cysteine protease and amine dehydrogenase, respectively. Our protein-inorganic self-assembly approach provides a versatile method to fabricate complex biomaterials endowed with enzymatic functionality.

Self-assembled protein-inorganic hybrid supraparticles for enzyme immobilization

253rd National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.