General Background of SERS Sensing and Perspectives on Polymer‐Supported Plasmon‐Active Multiscale and Hierarchical Sensor Particles

Abstract

Surface‐enhanced Raman scattering (SERS) is one of the most powerful analytical techniques for the identification of molecules. The substrate, on which SERS is dependent, contains regions of nanoscale gaps (hotspots) that hold the ability to concentrate incident electromagnetic fields and effectively amplify vibrational scattering signals of adsorbed analytes. While surface plasmon resonance from metal nanostructures is a central focus for the SERS effect, the support of polymers can be significantly advantageous to provide larger exposure of structured metal surfaces for efficient interactions with analytes. Characteristics of the polymer particles such as softness, flexibility, swellability, porosity, optical transparency, metal‐loading ability, and high surface area can allow diffusion of analytes and penetrating light deeply that can enormously amplify sensing outcomes. As polymer‐supported plasmon‐active sensor particles can emerge as versatile SERS substrates, the microfluidic platform is promising for the generation of sensor particles as well as for performing sequential SERS analysis of multiple analytes. Therefore, in this perspective article, the development of multifunctional polymer–metal composite particles, and their applications as potential sensors for SERS sensing through microfluidics are presented. A detailed background from the beginning of the SERS field and perspectives for the multifunctional sensor particles for efficient SERS sensing are provided.

Recent Progress of Droplet Microfluidic Emulsification Based Synthesis of Functional Microparticles

“…Due to the size and shape dependent properties, [ 112 ] metal microparticles play an extremely important role in metallic materials. As a result of a high ratio of surface area to volume, metal particles, especially in nanoscale, can be selected as effective catalysts for certain reactions.…”

Molecular‐Orbital Delocalization Enhances Charge Transfer in π‐Conjugated Organic Semiconductors

“…[6] The plasmon resonance effect caused by hot electrons in the conduction band of organic semiconductors is much weaker than the extremely large plasmon resonance effect caused by the hot electrons of noble metals. [6,7,24] Therefore, the strong SERS activity of the MB molecules in the SERS spectra has very little contribution from the electromagnetic field enhancement mechanism due to the low intrinsic carrier concentration in organic semiconductor films. In addition, the contribution of Mie scattering resonances to spectral enhancement could easily be excluded according to the geometries of the PEDOT : PSS sol-amorphous structures.…”

Plasmonic gold dogbone nanorattles sniff out trace molecules through surface enhanced Raman scattering

“…Thus, the degree of hotspot enhancement is highly dependent on the shape of the nanoparticle in addition to its size and chemical composition. 7,15,[20][21][22] Therefore, the presence of sharp tips, edges, and corners on plasmonic metal nanoparticles can increase the efficiency of electromagnetic hotspot generation, which is desirable for a range of applications such as SERS sensing, [23][24][25] catalysis, 5,26 and bioimaging. 9,22 The present work describes the synthesis of a nanorattle, designated as a gold dogbone nanorattle (Au-DBNRT), which consists of a solid gold dogbone shaped core and a thin, porous gold shell.…”

“…7,15,[20][21][22] Therefore, the presence of sharp tips, edges, and corners on plasmonic metal nanoparticles can increase the efficiency of electromagnetic hotspot generation, which is desirable for a range of applications such as SERS sensing, [23][24][25] catalysis, 5,26 and bioimaging. 9,22 The present work describes the synthesis of a nanorattle, designated as a gold dogbone nanorattle (Au-DBNRT), which consists of a solid gold dogbone shaped core and a thin, porous gold shell. This nanorattle was synthesized using a wet chemical synthesis process and possesses structural characteristics such as a large surface area and porosity.…”