Biomaterial actuator of M13 bacteriophage in dynamically tunable plasmonic coupling structure

Nano-gap plasmonic nanostructures like nanoparticle on a metallic film (NPOM) exhibit enhanced near-field properties because of surface plasmon coupling. Utilizing metallic NPs shape, size, material choice, and dielectric film-induced nano-gap (or hot-spots), it is possible to exploit potential applications in sensors. To achieve dynamic sensing, the application of tunable nano-gaps in response to external stimuli has been attempted using biopolymers. M13 bacteriophages are viable candidates as nano-gap materials owing to their widely adjustable physicochemical properties by genetic engineering technology. Here, we demonstrate a collective light-scattering spectrum of the surface-enhanced plasmonic resonance characterized by the surface morphology of the employed M13 bacteriophage thin film. Our NPOM (Ag nanocube/M13 bacteriophage film/Au film) nanostructure revealed differences in experimental and simulated scattering peak wavelength shift when nano-gap size(s) are varied. An AFM (Atomic Force Microscopy) surface morphology analysis of the M13 bacteriophage film showed its non-uniform thickness distribution explaining the differences in scattering peak wavelength properties. We confirmed that the M13 bacteriophage performs well as a sensor based on static and dynamic moisture exposure. Benefitting from the adaptability and sensitivity of the M13 biomaterial, our gap plasmonic coupling structure can be used for sensing VOCs as a biosensor.