Investigation of Controlled Growth of Metal-Organic Frameworks on Anisotropic Virus Particles.

Biomimetic mineralization with metal-organic frameworks (MOF), typically zeolitic imidazolate framework-8 (ZIF-8), is an emerging strategy to protect sensitive biological substances against denaturing environmental stressors such as heat and proteolytic agents. Additionally, this same biomimetic mineralization process has the potential of being used to create distinct core-shell architectures using genetically or chemically modified viral nanoparticles. Despite the proliferation of examples for ZIF-8 growth on biological or proteinaceous substrates, systematic studies of these processes are few and far between. Herein, we employed the tobacco mosaic virus (TMV) as a model biological template to investigate the biomimetic mineralization of ZIF-8, which has been proven to be a robust MOF for encasing and protecting inlaid biological substances. Our study shows a systematic dependence upon ZIF-8 crystallization parameters, e.g., ligand to metal molar ratio and metal concentration, which can yield several distinct morphologies of TMV@ZIF-8 composites and phases of ZIF-8. Further investigation using charged synthetic conjugates, time dependent growth analysis, and calorimetric analysis has shown that the TMV-Zn interaction plays a pivotal role in the final morphology of the TMV@ZIF-8, which can take the form of either core-shell bionanoparticles or large crystals of ZIF-8 with entrapped TMV located exclusively on the outer facets. The design rules outlined here, it is hoped, will provide guidance in biomimetic mineralization of MOFs on proteinaceous materials using ZIF-8.