3.Nanomechanical Charaterization of TMV Superlattice

Tobacco mosaic virus (TMV) and TMV-derived materials have demonstrated their great potential in biomedical applications, where the mechanical properties are determining factors for their proper functionality and structural integrity. Recently, it has been found that a superlattice structure can be formed by two-dimensional hexagonal packing TMV self-assembly in Barium ions solution.

FIG. 1. Schematic of 2-D hexagonal packing FIG. 2.AFM height image of a single .

of TMVs to form superlattice TMV superlattice

In parallel to the exploration of possible applications of TMV superlattice, the mechanical properties were characterized by the atomic force microscopy (AFM) based nanoindentation. The elastic modulus of 2.14 GPa was obtained by application of the extended Johnson-Kendall-Roberts (JKR) model with the force v.s. sample deformation data. The adhesion force was taken into consideration, and an easy-to-implement approach of using the extended JKR model was proposed by modifying both the theoretical model and the experimental data.

FIG. 3. Numerical fitting of the processed experimental data and modified JKR model

Finite element analysis (FEA) was conducted to evaluate the reinforcing effect of the like-charge forces between the TMVs and the mechanical properties of the TMV superlattice. Using the Halpin-Tsai model, the transverse elastic modulus of the superlattice sample varied within 2.00 ~ 4.38 GPa, depending on the indentation locations.Attraction-repulsion equilibrium was found to maintain the packing of TMVs. This provides useful information to address the sources of the attraction and repulsion forces to control the TMV assembly.

*The paper on this work has been published in the Journal of Applied Physics. 113, 2, 024308 (2013). DOI: 10.1063/1.4774103. http://jap.aip.org/resource/1/japiau/v113/i2/p024308_s1

Selected References:

1. K. L. Johnson, K. Kendall, and A. D. Roberts, Proceedings of the Royal Society of London Series a-Mathematical and Physical Sciences 324, 301-313 (1971).

2. D. Maugis, Langmuir 11, 679-682 (1995).

3. T. Li, R. E. Winans, and B. Lee, Langmuir 27, 10929-10937 (2011).