Surface-Enhanced Spectroscopy Techniques in Nanomaterials

Surface‐enhanced spectroscopy encompasses a suite of analytical methods that exploit the intense electromagnetic fields generated by plasmonic nanostructures to amplify otherwise weak inelastic light scattering from molecules. By tailoring the size, shape and assembly of metallic nanoparticles—typically gold or silver—researchers create “hot spots” where the local field enhancement can exceed 10^8, enabling detection down to the single‐molecule level. Two primary modalities are surface‐enhanced Raman scattering (SERS), a one‐photon process, and surface‐enhanced hyper‐Raman scattering (SEHRS), a non‐linear two‐photon analogue that provides complementary vibrational information. Recent developments have focused on multi‐resonant substrates that align plasmon resonances with both excitation and Stokes frequencies, on exploiting Fano resonances in complex oligomeric assemblies for ultrahigh enhancement, and on extending excitation into the near‐infrared and short‐wave infrared regions to reduce background fluorescence and improve penetration in biological samples. These advances underpin applications in chemical sensing, environmental monitoring, single‐cell diagnostics and material characterisation, highlighting the global impact of surface‐enhanced spectroscopy in nanoscience and beyond.

Research from Nature Portfolio

Recent studies have demonstrated theoretical design strategies for plasmonic substrates that simultaneously support multiple resonances and achieve enhancement factors exceeding 10^9 for hyper‐Raman scattering. One approach employs silver “nanorice” structures engineered to produce co‐located longitudinal plasmon modes at both pump and second‐order Stokes wavelengths, maximising the non‐linear signal. Building on this concept, a three‐particle silver nanorice trimer has been shown through simulation to generate Fano resonances that further concentrate electromagnetic fields in shared hot spots, yielding calculated enhancement factors above 10^13. These designs illustrate how judicious control of particle geometry and inter-particle coupling can produce ultrahigh‐sensitivity SEHRS substrates, setting the stage for experimental realisation and practical biosensing platforms.

Research from all publishers

Advances in bio‐probing with non‐resonant SEHRS have demonstrated the viability of short‐wave infrared excitation at 1 550 nm to probe labelled cells with minimal photodamage. By employing citrate‐stabilised gold and silver nanoparticle aggregates functionalised with reporter molecules, researchers have recorded two‐photon excited spectra of small biomolecules and drugs within live macrophage cells, illustrating potential for in situ cellular diagnostics. In a separate development, polymer‐templated silver nanoparticle hybrids prepared by polymerisation‐induced self-assembly have been shown to serve as highly active SERS substrates for adenine detection. Tuning the polymer–metal interactions through copolymer composition led to a 20-fold increase in signal compared with earlier systems, emphasising the role of hybrid organic–inorganic nanocomposites in enhancing sensitivity and selectivity for analytical applications.

Surface-Enhanced Spectroscopy Techniques in Nanomaterials publication trend

The graph below shows the total number of articles in surface-enhanced spectroscopy techniques in nanomaterials across all publications each year (not limited to Nature Index journals).

Technical terms

Plasmon resonance: Collective oscillation of conduction electrons in a metallic nanoparticle induced by incident light, leading to intense local electromagnetic fields.

Surface‐enhanced Raman scattering (SERS): One‐photon Raman technique in which plasmonic fields amplify the inelastic scattering signal of molecules near a metallic surface.

Surface‐enhanced hyper‐Raman scattering (SEHRS): Two‐photon Raman process enhanced by plasmonic nanostructures, offering complementary vibrational information to SERS.

Hot spots: Highly localised regions of extreme electromagnetic field enhancement found in gaps or junctions between plasmonic nanostructures.

Electromagnetic enhancement mechanism: Dominant contribution to surface enhancement arising from amplification of optical fields by plasmon resonances.

Fano resonance: Interference phenomenon between bright and dark plasmon modes that produces asymmetric line shapes and can concentrate electromagnetic energy in narrow spectral regions.

References

1. Surface enhanced hyper Raman scattering (SEHRS) and its applications. Chemical Society Reviews (2017).
2. Theoretical investigation of a plasmonic substrate with multi-resonance for surface enhanced hyper-Raman scattering. Scientific Reports (2018).
3. Plasmon coupling nanorice trimer for ultrahigh enhancement of hyper-Raman scattering. Scientific Reports (2021).
4. Bio‐probing with nonresonant surface‐enhanced hyper‐Raman scattering excited at 1,550 nm. Journal of Raman Spectroscopy (2020).
5. Effective SERS materials by loading Ag nanoparticles into poly(acrylic acid-stat-acrylamide)-block-polystyrene nano-objects prepared by PISA. Polymer (2021).