Chapter 22 - Metallic nanoparticle-based nano-inks for chemical and biological sensing

Abstract

The collective properties of an ensemble of metallic nanostructures become significantly altered compared with the algebraic sum of all the individuals, and this has given birth to the emergence of communal properties to the system. Although metallic particles at the nanometer length scale are susceptible to rapid and irreversible coalescence, recent advances in synthetic strategies have enabled the organized arrangement of nanostructures in colloidal dispersion or on solid substrates. Among the different approaches that can be adopted to utilize plasmonic characteristics, the assembly of nanostructures offers an avenue for varying degrees of plasmon coupling, eventually concentrating light into a small volume between neighboring nanostructures that renders their use in a diverse range of niche scientific and technological applications. The coupling of optical attributes at the same nanostructures could be miniaturized by governing their morphology and compositions to manipulate light–matter interactions at the bottom. Experimental observations and electromagnetic modeling to excavate the realm of light–matter interactions can be applied to elucidate problems in nanotechnology: to design synthetic strategies of size- and shape-selective nanostructures with unique optical properties, to study the properties of materials with variety of optical spectroscopies and imaging techniques, and to understand the interaction of plasmonic nanostructures and their surrounding molecular environment. Theoretical investigations, computational studies, and seminal experiments have illuminated the surface-enhanced spectroscopies of aggregated nanostructures that could pave the avenue for their applications in chemical and biological sensing, nonlinear optics, waveguiding, metamaterials, and photothermal ablation of cancerous cells. The future scope in this research arena have been elucidated.