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Surface-Enhanced Raman Scattering (SERS) offers exceptional sensitivity for trace-level molecular detection; however, its performance is highly contingent upon substrate design and data analytic methods. Here, we present a SERS substrate fabricated using femtosecond (fs) lasers for ultra-sensitive detection and real-time monitoring of perfluorooctanoic acid (PFOA) degradation. Femtosecond laser ablated nanoparticles were used for ultra-sensitive SERS probes. The SERS substrate showed stable detection of PFOA at concentrations as low as M with an estimated enhancement factor of ∼. Post-fabrication temperature treatment at yielded the greatest SERS activity, while higher temperatures (e.g., C) caused lower hotspot density due to nanoparticle coalescence, which was confirmed by nanoscopic analysis and hotspot mapping. The enhanced substrate was further used to trace the photocatalytic degradation of PFOA of varying concentrations. SERS spectra acquired over time reflected the continuous degradation and disappearance of representative PFOA peaks as well as the appearance of new peaks, which indicate successful degradation of molecules. Machine learning data analysis combined with density functional theory (DFT) calculations enabled the identification of several intermediate species. Taken together, these results highlight the promise of fs laser-fabricated, thermally tunable SERS substrates for ultra-trace molecular detection and advanced environmental monitoring applications. 

Surface-enhanced Raman spectroscopy (SERS) has evolved from a fundamental optical phenomenon to a powerful, molecule-specific analytical technique capable of detecting ultra-trace-level species across biomedicine, catalysis, environmental monitoring, and national security applications. In this review, we summarize recent advances in SERS probe design and fabrication along three major directions: (i) engineering plasmonic hotspots with enhanced field confinement to achieve stronger and more uniform signals; (ii) analyte-directed strategies that precisely position and retain target molecules via tailored surface chemistries, nanoscale confinement, and on-surface reactions for single hotspot SERS; and (iii) hybrid architectures integrating plasmonic metals with functional materials, including high entropy materials, semiconductors, and graphene and other 2D materials, to synergistically couple electromagnetic and chemical enhancement mechanisms. Despite significant progress, key challenges remain for practical applications outside laboratories, including substrate reproducibility and stability, diverse analyte compatibility, unknown molecule identification and standardized quantitative performance in complex environments. We highlight emerging solutions, such as large-area nanomanufacturing for controlled nanoscale gaps, high-resolution Raman mapping for spatial–temporal characterization, density-functional-theory-guided molecular interpretation, and machine-learning-enabled spectral analysis. Advances in foundational AI models and data-driven discovery are positioning SERS to become an increasingly versatile platform, from decoding unknown molecular structures to analyzing complicated multi-component systems for environmental, biomedical, and national security applications with high sensitivity and selectivity. 

We report that boron -containing zeolite chabazite (B-CHA) catalyzes the oxidative dehydrogenation of ethane (ODHE) with high selectivity (>70 %) and excellent stability in the temperature range of 500-600 degrees C. ODHE rates, in fact, increase over time on stream. Ethane consumption rate has an apparent activation energy of 126 kJ mol(-1), with Langmuirian dependence on the oxygen partial pressure and first-order dependence on the ethane partial pressure. Investigation of the catalyst before and after reaction by one-dimensional B-11 magic angle spinning (1D B-11 MAS) nuclear magnetic resonance (NMR), two-dimensional B-11 multiple quantum MAS (2D B-11 MQMAS) NMR spectroscopy, and Fourier transform infrared (FTIR) spectroscopy identifies the B-OH group in defect trigonal boron (B(OSi)(OH)(2)) as the species initiating the ODHE reaction. This result could open a pathway to develop suitable catalysts for industrial ethylene production with lower greenhouse gas emissions than current non -oxidative dehydrogenation routes. 

Despite the importance of proline conformational equilibria (trans versus cis amide, exo versus endo ring pucker) on protein structure and function, there is a lack of convenient ways to probe proline conformation. 4,4-Difluoroproline (Dfp) was identified to be a sensitive 19F NMR-based probe of proline conformational biases and of cis-trans isomerism. Within model compounds and disordered peptides, the diastereotopic fluorines of Dfp exhibit similar chemical shifts (FF = 0–3 ppm) when a trans X–Dfp amide bond is present. In contrast, the diastereotopic fluorines exhibit a large (FF = 5–12 ppm) difference in chemical shift in a cis X–Dfp prolyl amide bond. DFT calculations, X-ray crystallography, and solid-state NMR spectroscopy indicated that the FF directly reports on the relative preference of one proline ring pucker over the other: a fluorine which is pseudo-axial (i.e. the pro-4R-F in an exo ring pucker, or the pro-4S-F in an endo ring pucker) is downfield, while a fluorine which is pseudo-equatorial (i.e. pro-4S-F when exo, or pro-4R-F when endo) is upfield. Thus, when a proline is disordered (a mixture of exo and endo ring puckers, as at trans-Pro in peptides in water), it exhibits a small . In contrast, when the Pro is ordered (i.e. when one ring pucker is strongly preferred, as in cis-Pro amide bonds, where the endo ring pucker is strongly favored), a large  is observed. Dfp can be used to identify inherent induced order in peptides and to quantify proline cis-trans isomerism. Using Dfp, we discovered that the stable polyproline II helix (PPII) formed in the denatured state (8 M urea) exhibits essentially equal populations of the exo and endo proline ring puckers. In addition, the data with Dfp suggested the specific stabilization of PPII by water over other polar solvents. These data strongly support the importance of carbonyl solvation and n* interactions for the stabilization of PPII. Dfp was also employed to quantify proline cis-trans isomerism as a function of phosphorylation and the R406W mutation in peptides derived from the intrinsically disordered protein tau. Dfp is minimally sterically disruptive and can be incorporated in expressed proteins, suggesting its broad application in understanding proline cis-trans isomerization, protein folding, and local order in intrinsically disordered proteins.