Multidimensional Self-assembly Based On Tobacco Mosaic Virus Coat Protein

Virus coat proteins have been extensively employed as templates for the fabrication of novel nanomaterials and nanodevices due to their simple structures and easily being modified.Currently,most of the works were focused on the innate virus structures.However,the finite innate structures restrict the development of nanotechnology,the more controllable,complicated and functionalized virus-based structures need to be exploited and constructed.Innate self-assembly behavior can be changed via the rationally genetic or chemical modification,which offers the possibility for the fabrication of extended multidimensional structures.In this work,the classical rod-like virus nanoparticle,tobacco mosaic virus coat protein(TMVcp),was employed and genetically modified.On the account of the introduction of cysteine on its outside surface,the innate self-assembly behavior was changed and the two-dimensional well-ordered array and three-dimensional bundle were constructed via the self-assembly in vitro.This work includes following sections:Based on the TMVcp structure,the first and third amino acids of TMVcp were selected for the cysteien-mutated sizes.Three different mutants(T103C-TMVI cys?T103C-TMV3cys and T103C-TMV1,3cys)were cloned and expressed in the E.coli BL21(DE3)strain.The purified mutated TMVcp was obtained through ammonium sulfate precipitation and ion exchange chromatography.TEM observation indicated that the behavior of T103C-TMV1 cys and T103C-TMV3cys self-assembly were not much difference with the control T103C-TMVcp when they were incubated in same condition.However,the self-assembly behavior of the mutant T103C-TMV1,3cys was totally different with the other mutants and T103C-TMVcp,which can self-assemble into two-dimensional high-ordered disk-arrays and three-dimensional elongated bundles.The self-assembly process of these TMV-extended structures were observed by TEM and DLS.The prepared disk-arrays and bundles were executed at different pH values.TEM was employed to examine the results,demonstrating that these extended structures possess a satisfactory structural stability and can maintain their structures in the buffer with the pH from 4.5 to 9.5.Disk-arrays and bundles would be disaggregated into dispersive disk and short rods when they were treated with TCEP,implying that the formations of these extended structures were mediated by the disulfide bond in the outside surface of T103C-TMV1,3cys disk.T103C-TMV1,3cys disk-array and dispersive T103C-TMV1,3cys disk were treated as templates to immobilize the 3.5 nm gold nanoparticles(AuNPs)via the junction of Au-S bond.10-14 AuNPs were immobilized around a T103C-TMV1,3cys disk and resulted in the formations of gold nanoring and AuNP-array.This work demonstrates that well-ordered multi-dimensional TMV-based superstructures were constructed and these new structures could be used as biological scaffolds applied into the exploitation of nanodevices.The fabrications of gold nanoring and AuNP array based on the T103C-TMV1,3cys disk and disk-array indicate these extended structures can be applied as promising nanoplatforms in nanotechnology.What's more,this convenient strategy of TMV-based extended self-assembly provides an exemplification for other virus coat proteins in the fabrications of high-dimensional functionalized platforms.