Memory effect of reversibly thermoswitchable self-assembly-competent recombinant TMV coat protein with multi-binding moieties with potential applications in nanoparticle purification

Biomolecule-mediated assembly of novel nanoconjugates has been subjected to numerous investigations nowadays, which provides a new insight into the material science and engineering. Via the molecular biology technology, the genetically engineered polypeptide for inorganics (GEPI) can be designed as a molecular binder into the bio-scaffold to assemble hybrid functional nanoarchitectures. In the present work, we constructed a multi-functional virus-like particle (VLP) scaffold based on the Tobacco mosaic virus (TMV) (wild-type strain U1) in a facile way. The S123C site-mutated coat protein (CP) of TMV recombinated with a Ti–GEPI and 6-histidine tag (His tag) was successfully cloned, expressed and purified. The as-produced r-CP products retained both binding affinity for inorganic nanoparticles and self-assembly capability. Analysis of r-CP self-assembly during condensation polymerization was conducted. The r-CP-assembled aggregates including disc-like structures and rod-like VLPs were recovered by preparative size-exclusion chromatography (SEC) and then examined by TEM analysis. Notably, r-CP protein displayed a thermo-triggered reversibly switchable transition between bistable states of transparency and opaqueness. Western blot analysis, Immunogold labelling and TEM analysis were employed to test the existence and binding function of the His tag group in r-CP VLPs. Furthermore, dispersion of TiO₂ NPs in r-CP solution and recyclable application in bio-benefication was introduced. Here we demonstrated the possibilities of combining peptide-mediated immobilization with VLP-based biotemplate bearing multi-binding moieties for prospectful functional applications.