Supraparticle Nanoassemblies with Enzymes

Supraparticles are micelle-like self-limited assemblies from inorganic nanoparticles (NPs), whose size and morphology are determined by the equilibrium between short-range attraction and long-range repulsion forces. They can be spontaneously assembled from a variety of nanoscale components that are, in the majority of cases, the same NPs. Hybrid supraparticles made from inorganic and biological components are possible but hardly known. We report here the self-assembly of hybrid bioinorganic supraparticles, prepared from iron disulfide, cadmium telluride, and zinc oxide NPs as well as protease, cytochrome c, and formate dehydrogenase, in which the protein content can exceed that of NPs by 3:1. The resulting bioinorganic supraparticles are 70-150 nm in diameter and have a narrow size distribution. Five different permutations of inorganic and biological components indicate the generality of the observed phenomena. Coarse-grained molecular dynamics simulations confirmed that the formation of supraparticles depends on the interplay between attraction strengths and electrostatic repulsion. Enzymatic activity of the native protein is retained and is completely recovered from the assemblies, which suggests that the supraparticles can be utilized for encapsulation of biomolecules.