The development of effective methods for the detection of indication of protein misfolding is highly beneficial for early stage medical diagnostics and prevention of many neurodegenerative diseases. Self-assembled plasmonic nanoantennas...

Modulating single molecule emission of weak quantum emitters close to metallic nanostructures through plasmonic coupling interactions have uprooted the realization of plasmonic devices-based diagnostics platforms. The complex nanoscale geometries radically engineered by DNA origami technique to optimally position a single fluorophore in the vicinity of overlapping plasmonic fields of nanostructures are a benchmark to efficiently harness the coupled electromagnetic radiation. In this report, bimetallic Au@Ag nanostars (NSs) nanoantenna site-specifically arranged by DNA origami technique is employed for the fluorescence enhancement of a single Cy3 dye positioned at the interparticle gap between the nanostructures. A maximum of ∼65-fold enhancement of Cy3 dye is observed using fabricated dimeric assemblies of Au@Ag NSs. Additionally, to expand the utility of ultrasmall detection volumes of assembled dimer nanoantenna, the fluorescence enhancement of a small biologically relevant molecule is explored using crystal violet dye as the probe, attaining a maximum of ∼42-fold enhancement. Achieving significant fluorescence enhancement is a prerequisite for exploring the exciting aspects of biomolecular interactions at the single molecule level or the design of miniature photonic devices. The present work adds a new tool in the design of coupled nanoantennas exhibiting fluorescence enhancement and can be further developed for emerging applications in point of care diagnosis.

Core‐shell nanostructures of silicon oxide@noble metal have drawn a lot of interest due to their distinctive characteristics and minimal toxicity with remarkable biocompatibility. Due to the unique property of localized surface plasmon resonance (LSPR), plasmonic nanoparticles are being used as surface‐enhanced Raman scattering (SERS) based detection of pollutants and photothermal (PT) agents in cancer therapy. Herein we demonstrate the synthesis of multifunctional silica core ‐ Au nanostars shell (SiO2@Au NSs) nanostructures using surfactant free aqueous phase method. The SERS performance of the as‐synthesized anisotropic core‐shell NSs was examined using Rhodamine B (RhB) dye as a Raman probe and resulted in strong enhancement factor of 1.37 × 106. Furthermore, SiO2@Au NSs were also employed for PT killing of breast cancer cells and they exhibited a concentration‐dependent increase in the photothermal effect. The SiO2@Au NSs show remarkable photothermal conversion efficiency of up to 72% which is unprecedented. As an outcome, our synthesized NIR active SiO2@Au NSs are of pivotal importance to have their dual applications in SERS enhancement and PT effect.