Uniform dimensions and genetic tractability make filamentous viruses attractive templates for the display of functional groups used in materials science, sensor applications, and vaccine development. However, active virus replication and recombination often limit the usefulness of these viruses for such applications. To circumvent these limitations, genetic modifications of selected negatively charged intersubunit carboxylate residues within the coat protein of tobacco mosaic virus (TMV) were neutralized so as to stabilize the assembly of rod-shaped virus-like particles (VLPs) within bacterial expression systems. Here we show that TMV-VLP nanorods are easily purified, stable, and can be programmed in a variety of configurations to display functional peptides for antibody and small molecule binding.

A novel virus-like particle (TMV-VLP) receptor layer has been integrated with an optical microdisk resonator transducer for biosensing applications. This bioreceptor layer is functionalized with selective peptides that encode unique recognition affinities. Integration of bioreceptors with sensor platforms is very challenging due their very different compatibility regimes. The TMV-VLP nanoreceptor exhibits integration robustness, including the ability for self-assembly along with traditional top-down microfabrication processes. An optical microdisk resonator has been functionalized for antibody binding with this receptor, demonstrating resonant wavelength shifts of (Δλo) of 0.79 nm and 5.95 nm after primary antibody binding and enzyme-linked immunosorbent assay (ELISA), respectively, illustrating label-free sensing of this bonding event. This demonstration of label-free sensing with genetically engineered TMV-VLP shows the flexibility and utility of this receptor coating when considering integration with other existing transducer platforms.

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This paper presents an impedimetric microsensor that monitors nano sensing probe functionalization in real-time to optimize on-chip enzyme-linked immunosorbent assays (ELISA). The self-assembly dynamics of Tobacco mosaic virus-like particle (VLP) bioreceptors were studied using continuous measurement of the electrical impedance between the interdigitated microelectrodes, which contributed to an optimized and reduced VLP assembly time from 18 hours to 3 hours. The impedance sensor with optimized VLP assembly effectively sensed antibody binding in on-chip ELISA which showed a 64% higher impedance change compared to the control experiment. These results combined highlight the significant potential of genetically modified VLPs as selective nanostructured probes for rapid immunoassays.