Plasmonic sensitivity of noble metals has often been attributed to the morphology of the nanostructures and dielectric effects of both the materials and the surrounding medium. The measurable plasmonic shift with respect to the change in local dielectric as a function of analyte concentrations within nanoscale volume forms the basis of plasmonic sensing. However, the situation of the surrounding medium in the presence of multicomponent systems and, moreover, inhomogeneous adsorption around the anisotropic nanostructures become seemingly complicated as the precise description of several individual components becomes nearly impossible. Therefore, we have designed a retrospective formalism through a critical condensation of the electromagnetic scattering theories, macroscopic mixing rules, and micromechanics at the metal−analyte interface that can be adopted as generalized model irrespective of morphology of the nanostructures and the nature of analytes to account for the response of all the individual (microscopic) components to the observed (macroscopic) plasmonic sensing.

Cellular internalization of plasmonic metal nanostructured materials has recently become a requisite for biomedical engineering of several intracellular processes that could foster an extensive paradigm to perform desired functions in the living cells. While numerous anisotropic metal nanostructures can be employed to pursue the specific functions, their incorporation becomes restricted due to morphological specificity to be engulfed in the cells. Due to recent advent in the self-assembly strategies, individual gold nanospheres could be interdigitated to one-dimensional plasmonic polymers and undergo subsequent laser-induced photothermal reshaping to rod-like nanostructures. The salient feature of biological significance is merely the variation of particle size within the polymers that engenders a dramatic impact on the radiative and nonradiative properties expressed in the scale of Faraday number ( F a ) and Joule number ( J 0 ), respectively, as a function of the aspect ratio (α) of the nanorods. The effect on the nonradiative properties augments designing of nanoscale thermometry essential for photothermal applications in living cells. The conception of the colloidal dispersion has been extended to the cellular environment in a mice model; the selective accumulation of the nanostructures in the cells could provide an invading relationship between plasmonic characteristics, temperature distribution, and the biological issues. The critical correlation between optical and thermal characteristics toward biomedical manipulation from both theoretical and experimental perspectives could augment a milestone toward the progress of modern medical sciences.

The correspondence between plasmonics and electronics has been determined through the mechanics of gold nanorod dimers from both theoretical and experimental perspectives.

Plasmonic aspects of anisotropic nanostructures have been a subject of considerable interest over the proposition of electromagnetic scattering theories in the past century. Since an accurate description is not possible in the polar coordinates, Gans modified Mie scattering theory for metal spheres assuming the shape of a rod-like scatterer as an approximated case of infinitely elongated ellipsoid (R ≪ L) so that the contributions of end-caps can be neglected. Due to prudent sophistication in the nanoscale synthetic strategies, a plethora of correlated rod-like nanostructures with diverse end-cap geometries have been synthesized. Experimental measurements have elucidated that a seemingly minor change in end-cap morphology of the nanorods imbues distinctly different optical characteristics; therefore, the consideration of adequate contributions is obvious to the electromagnetic modeling of realistic geometry of the nanorods. Since the basic philosophy of science is to dissect similar observations into diverse magnification, we focus to enumerate the pragmatic change in shape toward scattering characteristics employing topology as a general description of the realistic rod-like nanostructures. Two widely different structures, nanodumbbells (extreme case of dogbone-like nanorods) and nanobars have been considered as the two extremities of rod-like geometries. The geometries have been described through proper functional assignment of their shape functions that have been adopted for electromagnetic simulations. These methodologies lead to achieve a general solution to substantiate the observed plasmonic response of the realistic rod-like nanostructures.