SYNTHESIS OF NANOSTRUCTURES USING VIRUS AS BIOTEMPLATES

Bio-systems inherently have molecular recognition and capability of self assembly, thus are good templates for constructing and organizing nanostructures.

Hence, viruses are used to synthesize and assemble nanostructures.

For maximum potential, monodisperse, homogeneous ,nanomaterials and hierarchical organization control are needed.

Two types of nanomaterial synthesis by virus is possible: Intracellular & extracellular

Three mechanism for using virus for biological synthesis:• Virus biological components as template e.g. DNA strand

or protein cages for synthesis. • Bio mineralisation.• Viruses as vector.

INTRODUCTION

Size range: approx. 10 nm to more than a micron, is unique for organic structures characterized at atomic resolution as compared to large sized colloids and polymers.

Viruses are often perfectly monodisperse.

Variety of distinct shapes (most commonly icosahedrons, spheres, tubes, and helices) and with various properties (such as varying sensitivities to pH, salt concentration, and temperature).

Constrained interior spaces that are accessible to small molecules but often impermeable to large ones, offering opportunities for assembly and packaging of cargoes.

PROPERTIES OF VIRUSES HELPING BIOLOGICAL SYNTHESIS

Their composition may be controlled by manipulation of the viral genome.

They represent the ultimate examples of self-assembly and polyvalence.

They can be made in quantity(0.1%–1% by weight).

They are often more stable toward variations of pH, temperature, and solvent than standard proteins, thereby providing a wider range of conditions for their isolation, storage, and use.

They have large surface areas, which allow for the display of many copies of the same molecule or many different molecules, without concerns of steric crowding.

PROPERTIES OF VIRUSES HELPING BIOLOGICAL SYNTHESIS (contd.)

DIFFERENT VIRUSES

Virus/nanoparticle architectures with morphological and functional complexity. Low- (A) and high- (B) magnification TEM micrographs showing wild-type TMVs with dense external coating of gold nanoparticles. Inset: corresponding energy-dispersive X-ray (EDX) spectrum showing Au (and Cu from supporting grid) signals. (C) Cut-away view of a ribbon diagram of the cowpea chlorotic mottle virus showing the central cavity of the protein cage. (D) Superimposed iron (yellow) and nitrogen (blue) electron energy-loss spectrum images of iron oxide-filled CCMV (common scale bar at bottom is 33 nm). The compositional maps clearly show that the mineral core is contained within the protein shell. (E,F,G) Unstained TEM images of gold nanoparticles bound to isolated mutant CPMV virus (left) and corresponding models (right). (E) The BC mutant can accommodate one 5-nm gold nanoparticle per fivefold axis. (F) The EF mutant offers five accessible binding sites for each of the twelve fivefold axes. (G) Forty-two of the 120 possible sites of the DM mutant are observed to be occupied by 2-nm nanoparticles.

Virus biological component as template for nanoparticles

synthesis

Viruses are protein superstructures that offer ready-to-use chemical platforms for synthesis and assembly of nanoparticles and nanostructures.

They are bio-derived templates with precisely defined topology, symmetry, and morphology.

Viruses protect their genetic material by enclosing it within protein cages with diameters of 26, 65, or 125 nm. Filament or rod-shaped viruses either produce a long, thin protein enclosure to contain the plasmid DNA (e.g., bacteriophage M13), or coil a RNA strand within a helicoidal protein nanotubules.

PROPERTIES ENABLING VIRUSES TO BE BIO TEMPLATES

One can remove the RNA strand from the cavity of chlorotic cowpea mottle virus (CCMV) and purify the empty icosahedral virion. The resulting highly cationic inner surface consists of 1080 arginine and 540 lysine groups that facilitate the intake of anionic precursors such as aqueous tungstate ions which, on acidification, aggregate into polyoxotungstate NPs entrapped within the CCMV cavity.

CASE STUDY: Icosahedral virion

BIOMINERALIZATION{Nature’s bio minerals hold the key to

designingunique nanostructures for human health

and industrial applications.-Lawrence Livermore National

Laboratory}

Through a process called biomineralisation, proteins orchestrate the growth processes of many natural minerals into designs that confer exceptional properties.

The biological controls that determine the size, shape, and properties of crystals are key to addressing challenges as diverse as synthesizing nanostructures, characterizing climate change, treating disease, and designing new materials for national security applications.

Proteins Modify Growth:• Accelerate e.g. proteins of abalone and oyster shells• Inhibit :

Arctic fish must live in subfreezing environments without developing ice crystals in their blood. If it were not for the inhibitory effect of certain proteins, the supersaturation

of calcium phosphates and oxalates in human blood and urine would be enough to turn a human into a proverbial pillar of salt.

Experimental case study

Aim: Use viruses to synthesize and assemble nanowires of cobalt oxide at room temperature.

In order to attain maximum potential, monodisperse, homogeneous ,nanomaterials and hierarchical organization control are needed.

Bio-systems inherently have the molecular recognition and the capability of self assembly, thus are attractive template for constructing and organizing the nanostructure.

This biological route uses room-temperature, aqueous synthesis conditions.

ABSTRACT

M13 virus consists of approximately 2700 major coat proteins (p8) helically wrapped around its single stranded DNA, and of minor coat proteins (p3, p6, p7, and p9) at each end of the virus. The functionality of these subunit proteins can be modified specifically through additions in the M13 genome.

Modification of major coat proteins as well as minor coat proteins at the virus ends has been successfully demonstrated to form functional heterostructured templates for precisely-positioned nanomaterials.

Intrinsically anisotropic virus structures are well-suited for growth of monodisperse, highly crystalline nanowires. Predictive based design was used to engineering the virus to satisfy the multifunctional purpose of electrode formation and assembly with a polymer electrolyte for the Li ion battery.

Tetra-glutamate was fused to the N-terminus of each copy of the major coat p8 protein with one hundred percent expression. This clone, named the E4 clone, was designed with two distinct purposes:• A general template for growing nanowires through the interaction of the

glutamate with various metal ions.• The side chain of glutamate, binds positive metal ions via ion exchange,

as demonstrated in polymeric templates.

M13 VIRUS (DETAILED)

Schematic diagram of the virus enabled synthesis and

assembly of nanowires as negative electrode materials for lithium ion

batteries

Rationally designed peptide and/or materials specific peptides identified by biopanning were expressed on the major coat p8 proteins of M13 viruses to grow Co3O4 and Au/ Co3O4 nanowires.

Macroscopic ordering of the engineered viruses was utilized for fabricating an assembled monolayer of Co3O4 nanowires for flexible, light weight Li ion batteries.

PRINCIPLE

THANK YOU

VIDUR RAJ SINGHSANTOSH PARAM SIVAMAKASH SINGH CHAUHAN

SIRI KIRAN REDDYSUPRIYA SUSHANT

KRISHNAMURTI CHATURVEDIASHANG LUWANG LAIVAVEMURI VAMSEEDHARA