Surface-enhanced Raman spectroscopy for chemical and biological sensing using nanoplasmonics: The relevance of interparticle spacing and surface morphology

Abstract

In this review, the weightiest decadal developments of surface-enhanced Raman scattering (SERS) and nanoplasmonic materials in sensing applications are discussed. Today, there are several well-established research directions where plasmonic detection is employed extensively, namely, food and water quality monitoring, viruses, pathogenic bacteria and hazardous toxin investigations for theranostic applications, and explosive substance detection for military and civil protection purposes. A combination of vibrational spectroscopy and surface nanoengineering has gained a reputation as a powerful weapon for rapid and accurate determination of submolecular quantities of nanoanalytes. Signal enhancement achieved by employing various metallic nanoparticles and nanostructures can be amplified significantly due to the electromagnetic field confinement effect. Localized surface plasmon waves, which are responsible for the phenomenon, promote light absorption at nanovolume, generating ‘hot spots’ with an incredibly intense and confined electromagnetic field close to the nanosculptured metallic surface. However, the formation of the hot spot network is heavily dependent on morphology, size, and spatial arrangement of plasmonic nanomaterials. Under optimal excitation conditions, the interaction between the optically induced electromagnetic field in the hot spot region and a probing analyte attached to the nanosculptured metallic substrate enlarges photon scattering cross section, increasing signal intensity by 106–1010. As a result, fast single-molecule vibrational fingerprint recording is possible. This focused review collects recent state-of-the-art developments in nanoplasmonic SERS sensing, highlighting the most efficient surface morphology designs that hold the most promise for future developments.

Femtosecond Laser Structuring for Flexible Surface-Enhanced Raman Spectroscopy Substrates

“…Additionally, instead of the outstanding flexibility, the L-PTFE-Ag membrane can be used to develop high-performance SERS substrates because of the LSPR effect and 3D micro-/nano-structures. The 3D micro-/nano-structures are helpful to enhance the internal light reflection, leading to the improvement of SERS performance [66][67][68][69][70][71]. In order to characterize microstructures of samples, CLSM was used to examine the surface morphology of PTFE, L-PTFE, and L-PTFE-Ag (Fig.…”

“…The combination of these two advantages mentioned above plays a vital role in developing PTFE-based SERS substrates. Appropriate diameter and spacing of silver nanoparticles (AgNPs) will help to improve the SERS performance [1,69,72]. As a pioneer, Kumar et al reported flexible SERS substrates with AgNPs on grating PDMS structures that combine LSP and surface plasmon polariton structures [73,74].…”

Plasmonic biosensors for food control

“…Similarly, to achieve SERS, the Raman active molecule is placed within the localized electric field of the plasmonic nanostructures such that the molecule will experience an increased Raman scattering cross-section and hence, enhanced Raman signal (Barbillon, 2020;Hamm, Gee, & De Silva Indrasekara, 2019;P. Li et al, 2020;Shvalya, Filipič, Zavašnik, Abdulhalim, & Cvelbar, 2020). Due to the specific fingerprints of fluorescence at molecular level, SERS has shown several advantages of high selectivity, single molecule detection, and molecular characterization, and in addition high throughput, point-of-care applicability, and easy sample preparation.…”

Porous Hybrids Structure between Silver Nanoparticle and Layered Double Hydroxide for Surface-Enhanced Raman Spectroscopy

“…Since the SERS effect was first observed with pyridine which was adsorbed on rough Ag electrode [ 12 ], various techniques have been suggested to develop substrates with enhanced SERS properties. The SERS effect is known to be mediated by two principles, electromagnetic mechanism (EM) and chemical mechanism (CM) [ 13 , 14 , 15 ]. The EM is a long-range effect originated from an enhanced electromagnetic field and it depends on the morphology of the substrate.…”