Surface-enhanced Raman spectroscopy (SERS) is a powerful analytical technique, which allows quantitative detection of chemical species with molecular specificity and single-molecule sensitivity. These useful properties can be further combined with portable Raman spectrometers which allow SERS to be potentially employed at the point-of-care. As a result, SERS has found a wide range of potential applications in both real-life chemical analysis and fundamental mechanistic studies. Despite these advantages, true applications of SERS have been limited due to its high cost, which arises mainly from the fact that SERS relies on expensive single-use Ag/Au enhancing substrates suitable only for the analysis of pure samples. A viable approach to address this issue is to develop multifunctional SERS substrates, which in addition to providing Raman signal enhancement, is armed with other practical functionalities that simplifies the analysis and/or allows the substrate to be regenerated for repeated use. This review gives an account of the recent progress in the fabrication of multi-functional SERS substrates, namely flexible, separation-enhancement-in-one, calibration-enhancement-in-one and regeneration-enhancement-in-one substrates. Specific focus is placed on summarizing and discussing the most widely used strategies to incorporate each type of functionality and their respective advantages and drawbacks. Finally, we present our perspectives on the future challenges and potential opportunities in the development of smart multifunctional SERS sensors for achieving sustainable and wide-spread application of SERS.

/pdf/towards-practical-and-sustainable-sers-a-review-of-recent-7al68aiuj1.pdf

Towards practical and sustainable SERS: a review of recent developments in the construction of multifunctional enhancing substrates

Charge-transfer dynamics at a Ag/Ni-MOF/Cu2O heterostructure in photoelectrochemical NH3 production.

Rapid component separation and reliable surface-enhanced Raman scattering (SERS) detection of organochlorine pesticide (OCP) residues in real water samples remain major challenges because of sample complexity, trace content, and low molecular affinity for a metal surface. Here, we report a novel strategy of simultaneous in situ extraction and fabrication of plasmonic colloidal gold superparticles (AuSPs) to perform rapid SERS detection of OCPs in environmental water. In this protocol, multiple components of OCPs in complex water were facilely diffused into dichloromethane (DCM) microdroplets and specifically bound to octadecylamine-modified gold nanoparticles (Au-ODAs), affording the SERS substrate through self-assembly of the OCP-trapped Au-ODA into AuSPs with the evaporation of DCM. SERS signals of the specifically prepared Au-ODA could be used as an internal standard to calibrate the absolute signal of OCPs, and multiplex detection could be achieved depending on their molecularly narrow Raman peaks. As for simultaneously sensing four kinds of OCPs (4,4'-DDT, α-endosulfan, tetradifon, and chlordane) in water, the established method showed strong anti-interference ability and comparable quantification ranges with a low limit of detection (LOD). The recoveries ranged from 90.20 to 109.4% for OCPs in farmland, river, and fishpond water, indicating that the established AuSP-based platform is reliable and applicable to the detection of OCPs in real water samples.

Simultaneous In Situ Extraction and Self-Assembly of Plasmonic Colloidal Gold Superparticles for SERS Detection of Organochlorine Pesticides in Water

Two-dimensional (2D) MXenes are attractive candidates as surface-enhanced Raman scattering (SERS) substrates because of their metallic conductivity and abundant surface terminations. Herein, we report the facile synthesis of bimetallic solid-solution TiVC (MXene) and its application in SERS. The few-layered MXene nanosheets with high crystallinity were successfully prepared using a one-step chemical etching method without ultrasonic and organic solvent intercalation steps. SERS activity of the as-prepared MXene was investigated by fabricating free-standing TiVC film as the substrate. A SERS enhancement factor of 1012 and femtomolar-level detection limit were confirmed using rhodamine 6G as a model dye with 532 nm excitation. The fluorescent signal of the rhodamine 6G dye was effectively quenched, making the SERS spectrum clearly distinguishable. Furthermore, we demonstrate that the TiVC-analyte system with ultrahigh sensitivity is dominated by the chemical mechanism (CM) based on the experimental and simulation results. The abundant density of states near the Fermi level of the TiVC and the strong interaction between the TiVC and analyte promote the intermolecular charge transfer resonance in the TiVC-analyte complex, resulting in significant Raman enhancement. Additionally, several other probe molecules were used for SERS detection to further verify CM-based selectivity enhancement on the TiVC substrates. This work provides guidance for the facile synthesis of 2D MXene and its application in ultrasensitive SERS detection.

Two-Dimensional TiVC Solid-Solution MXene as Surface-Enhanced Raman Scattering Substrate.

Surface-enhanced Raman spectroscopy is an alternative detection tool for monitoring food security. However, there is still a lack of a conclusion of SERS detection with respect to pesticides and real sample analysis, and the summary of intelligent algorithms in SERS is also a blank. In this review, a comprehensive report of pesticides detection using SERS technology is given. The SERS detection characteristics of different types of pesticides and the influence of substrate on inspection are discussed and compared by the typical ways of classification. The key points, including the progress in real sample analysis and Raman data processing methods with intelligent algorithm, are highlighted. Lastly, major challenges and future research trends of SERS analysis of pesticide residue are also addressed. SERS has been proven to be a powerful technique for rapid test of residue pesticides in complex food matrices, but there still is a tremendous development space for future research.

Rapid field trace detection of pesticide residue in food based on surface-enhanced Raman spectroscopy

Noble metal nanoparticles (NPs) have enabled surface-enhanced Raman scattering (SERS) for in situ monitoring of NPs-catalyzed reactions. However, it still remains a great challenge to ensure that a...

Ruili Li

Papers

Simultaneous In Situ Extraction and Self-Assembly of Plasmonic Colloidal Gold Superparticles for SERS Detection of Organochlorine Pesticides in Water

“Pomegranate-Like” Plasmonic Nanoreactors with Accessible High-Density Hotspots for in Situ SERS Monitoring of Catalytic Reactions

AIEgen modulated per-functionalized flower-like IRMOF-3 frameworks with tunable light emission and excellent sensing properties.