Scattering Spectroscopy Research Articles

Fabrication of Surface-Enhanced Raman Scattering (SERS) Substrates in Analytical Science by Natural-inspired Materials: A Review

Surface-Enhanced Raman Scattering (SERS) spectroscopy, as a novel rapid detection technology, offers molecular fingerprinting capabilities that achieve trace-level detection. The key to optimizing SERS sensitivity and reliability lies in the precise control of the nanostructures of SERS substrates. Nature, through billions of years of evolution, has served as a masterful creator, developing organisms with remarkable abilities based on micro/nanostructures, such as the superhydrophobicity of lotus leaves and the strong adhesive forces of gecko feet. This review categorizes the recent developments in SERS substrates inspired by natural materials into three main types: plant-based, animal-based, and virus-based. Each category is explored in detail, describing how their unique nanoarchitectures inspire the development of highly sensitive SERS substrates, along with their fabrication methods and applications in analytical science. Additionally, the review identifies current challenges, such as the uniformity and scalability of naturally inspired SERS substrates and suggests future directions, including the integration of hybrid biomimetic structures and advanced manufacturing techniques. By fostering a deeper understanding of these nature-inspired materials, we aim to enhance the practical application of SERS in analytical science in the future.

Surface-Enhanced Raman Scattering Spectroscopy: An Effective Tool for the Detection of Environmental Pollutants

Surface-Enhanced Raman Scattering Spectroscopy: An Effective Tool for the Detection of Environmental Pollutants

CO2 utilization and on-purpose ethylene production: a chemical looping approach

CO2-assisted ethane dehydrogenation (CO2-ODHE) is a promising carbon atom economy process for upgrading CO2 to CO in tandem with C2H6 to C2H4 conversion. Iron oxide-based materials are selective for on purpose ethylene production through CO2-ODHE. The feed admission mode was found to play an important role on catalytic performance. Alternating C2H6 (reduction step) and CO2 (oxidation step) feedstock to a fixed bed reactor (chemical looping concept, CO2-ODHE-CL) attained constant ethane and CO2 conversion per step at 600oC, equal to ~17.6%, while C2H4 selectivity during the reduction step was ~75%. The lattice oxygen mobility is a descriptor for the materials used during the CO2-ODHE-CL, since low mobility resulted in an increased C-H bond scission selectivity, i.e., C2H4 production, during the reduction step. Temperature programmed 18O2 isotope exchange experiments, along with temperature programmed H2 – reduction, were employed to exemplify the latter statement, investigating the lattice oxygen reactivity of the examined materials and the mechanism through which the lattice oxygen is reacting. X-ray techniques (X-ray Diffraction, X-ray Raman Scattering Spectrometry, X-ray Absorption Spectrometry) along with structural modeling demonstrated that the formation of a spinel like arrangement between Mg and Fe, stabilized lattice oxygen and thus minimized the undesired C-C bond scission during the C2H6 step of CO2-ODHE-CL.

Label-Free Exosome Analysis by Surface-Enhanced Raman Scattering Spectroscopy with Laser-Ablated Silver Nanoparticle Substrate.

Early diagnostics of breast cancer is crucial to reduce the risk of cancer metastasis and late relapse. Exosome, which contains distinct information of its origin, can be the target object as a liquid biopsy. However, its low sensitivity and inadequate diagnostic tools interfere with the point-of-care testing (POCT) of the exosome. Recently, Surface-enhanced Raman Scattering (SERS) spectroscopy, which amplifies the Raman scattering, has been proved as a promising tool for exosome detection. However, the fabrication process of SERS probe or substrate is still inefficient and far from large-scale production. This study proposes rapid and label-free detection of breast cancer-derived exosomes by statistical analysis of SERS spectra using silver-nanoparticle-based SERS substrate fabricated by selective laser ablation and melting (SLAM). Employing silver nanowires and optimizing laser process parameters enable rapid and low-energy fabrication of SERS substrate. The functionalities including sensitivity, reproducibility, stability, and renewability are evaluated using rhodamine 6G as a probe molecule. Then, the feasibility of POCT is examined by the statistical analysis of SERS spectra of exosomes from malignant breast cancer cells and non-tumorigenic breast epithelial cells. The presented framework is anticipated to be utilized in other biomedical applications, facilitating cost-effective and large-scale production performance.

Complex Formation of Gold Nanoparticles with Collagen in Aqueous Media Studied by X-ray Scattering and Absorption Spectroscopy.

Small-angle X-ray scattering and UV-vis absorption measurements were performed on mixed solutions of gold nanoparticles (AuNPs) and atelocollagen (AC), triple-helical collagen without telopeptide, in acetate buffer at pH 4 under different temperature conditions, i.e., preparation temperature Tprep and measurement temperature Tmeas. Due to the significantly higher electron density of gold than that of AC, the structure factor S(q) of AuNPs is readily estimated from the scattering intensities of AuNP-only and mixed solutions. The resulting S(q) profile for the mixed solution indicated significant attractive interactions, especially for the smaller AuNPs. Therefore, the sticky sphere model was applied to analyze S(q) to determine the interaction parameters at different Tprep and Tmeas. The attractive interactions between AuNPs were higher at higher Tprep, suggesting that single-chain AC tends to make the interactions between AuNPs more attractive than those for triple-helical AC. Complex formation was also detected by the aggregation-induced surface plasmon absorption shift. More densely packed AuNPs were detected from the absorption spectra for higher AuNP content at which the ζ potential disappeared, while a split absorption band was also found, indicating that not all AuNPs can form a complex with AC at ζ = 0.

(Invited) Solid/Electrolyte Interface Under Confinement in Divalent Water-in-Salt Electrolytes

Concentrated aqueous electrolytes (water-in-salt electrolytes, WiSEs) have gained increasing attention in the last few years because they display much wider electrochemical stability windows (upwards of 3V) than the thermodynamic limit of water (1.23V), making them exciting candidates for a variety of electrochemical systems including aqueous batteries. Importantly, it is the ions directly at the electrode/electrolyte interface that are key to explaining this unexpected reactivity. The electrode/electrolyte interface is classically thought of as the electrical double layer (EDL), or the ion arrangement at an interface that builds up to neutralize the surface potential. WiSEs present very different EDL structures than do classical dilute electrolytes. However, most work has focused on monovalent WiSEs, primarily motivated by Li-battery applications using lithium bis(trifluoromethylsulphonyl)imide (LiTFSI).In this work, we aim to understand how divalent ions within the WiSE regime alter both the short-range and long-range signatures of the EDL under confinement. For most of the above applications, reactions occur within the pore-space of a porous electrode, which exhibit confined, overlapping EDLs. Therefore, we use confinement as a tool to probe both the short-range layering structure (<10 nm) and electrostatic decay length (~10-100 nm) away from a charged interface with Surface Forces Apparatus (SFA) measurements.Using WiSEs comprising LiTFSI, Zn(TFSI)2, and mixtures of the two salts, we first establish the bulk structure of these electrolytes using Wide Angle X-Ray Scattering and Raman Spectroscopy, which reveal that the anion and cation are closely associated in all electrolytes, regardless of cation valency. Additionally, clusters of ions are formed in all electrolytes, however, the clusters are suppressed with increasing divalent ion fraction. Under confinement, SFA results demonstrate that the thickness of the adsorbed layer of ions at a solid/electrolyte interface grows with increasing divalent ion fraction. Multiple interfacial layers are formed following this adlayer, and these layers seem dependent on anion size, rather than cation. Importantly, all electrolytes exhibit very long electrostatic decay lengths that are insensitive to valency. This work contributes significant fundamental understanding regarding the structure and charge-neutralization mechanism in this class of electrolytes both in the bulk and under confinement at an interface.

Towards the Direct Observation of the Local and Electronic Structure Evolution of Positive Electrode Materials by X-Ray Raman Scattering and X-Ray Emission Spectroscopy

The emergence of high brilliance synchrotron sources and the availability of more sophisticated infrastructure have opened doors to advanced material characterization, enabling a profound understanding of new processes and mechanisms in battery research. [1] More specifically, non-resonant Valence-to-Core X-ray emission spectroscopy (VtC-XES) and X-ray Raman scattering (XRS) stand out as complementary photon-in/photon-out X-ray spectroscopy techniques. The unique capability of these techniques lies in their access to soft X-ray edges using a hard X-ray beam, providing comprehensive information on both the electronic and local structure, due to their high sensitivity to local structure and coordination. [2,3] In this work, two different families of materials with different compositions and crystal structures are studied using XES and XRS.The first part focuses on the detailed study of oxygen substituted KVPO4F1-xOx (x = 0, 0.25, 0.5, 0.75, 1) using VtC-XES combined to ab initio theoretical calculations. The average working potential increases with increasing oxygen content by activating the V3+/4+ and V4+/5+ redox couples and replacing the VO4F2 “ionic” entity by {V=O}O5 unit with a highly “covalent” vanadyl-type bond. [4] VtC-XES allowed us to distinguish the contributions of V-F, V-O, and V=O bonds in the local environment, with spectral intensities highly correlated to the F- and O2- anionic composition. In addition, specific spectral evolutions are also associated to the presence of highly covalent V=O bonds, strongly influencing the electrode potential of the material.The second part examines a series of electrochemically obtained LiyNiO2 layered oxide materials (y = 0.02, 0.25, 0.33, 0.5, 0.67, 1.0). VtC-XES performed at the Ni Kβ emission line allows to study the local structure evolution around Ni, whereas XRS spectroscopy at both the O K-edge and Ni L2,3 L-edges gives an access to the interplay between Ni and O through the hybridized states of Ni 3d and O 2p. [5] This work provides a survey on both the cationic and anionic redox processes, and unveils the underlying phenomena related to the charge compensation processes occurring in this material.Overall, we present a comprehensive study of different polyanionic and layered oxide positive electrode materials using complementary X-ray spectroscopic techniques to probe both the local and electronic structures. We demonstrate that they allow to follow and understand evolution and changes in the local structure in materials of intricate crystal structures.AcknowledgementThis work was supported by the DESTINY Marie Skłodowska-Curie Actions COFUND PhD Programme (Grant Agreement #945357) co-funded by the European Union's Horizon2020 research and innovation program and the Synchrotron SOLEIL. ANR is also acknowledged for funding the RS2E network through the STORE-EX Labex Project ANR-10-LABX-76-01. Alistore-ERI network is also acknowledged.

Filamentous bacterial nanocelluloses decorated with dense Au nanoparticles for developing ultrasensitive SERS biosensors

Based on hydrogen peroxide (H2O2)-modified bacterial nanocelluloses (BNCs(M)), we report in-situ overgrowth of highly dense plasmonic Au nanoparticles (NPs) on these filamentous three-dimensional (3D) supports by an ingenious “green” photochemical strategy. The measured relative atomic ratio of Au element in the resultant BNCs(M)@Au NPs is ∼ 13 times higher than that formed on pristine BNCs. The BNCs(M)@Au NPs exhibit a higher surface-enhanced Raman scattering spectroscopy (SERS) activity than the reference BNCs@Au NPs. The flexible SERS biosensors enable the label-free detection limit of glucose molecules to be achieved as low as 10−10 M, surpassing many reports in previous works and then facilitating the ultrasensitive evaluation of glucose metallic diseases.

Oriented attachment of silver nanoparticles in DMSO by collapsing under thermal stress

Nowadays, understanding the behavior of nanoparticle agglomeration is crucial to gain insight into the fundamental physicochemical processes that govern particle interactions at the nanoscale. In this work, we are focused on the thermal collapse of silver nanoparticles (NPs) stabilized with sodium citrate in dimethyl sulfoxide (DMSO). Therefore, we investigated the parameters that influence the transition from nearly isolated particles to elongated Ag agglomerates using Dynamic Light Scattering (DLS) and Ultraviolet-Visible Spectroscopy (UV-Vis). In addition, we conducted an in-depth study of the near-particle-particle interaction within the agglomerate using High-Resolution Transmission Electron Microscopy (HRTEM) observations of the agglomerates. The HRTEM results suggest that in the elongation of the agglomerate, the oriented attachment within the initial cluster plays a crucial role in the alignment along the longitudinal axis. The aging colloid exhibits minimal agglomeration, suggesting that the driving force of the collapse phenomenon is predominantly thermodynamic rather than kinetic in nature, and that the surface chemical equilibria play a key role in the preferential orientation mechanism.

Portable point-of-care surface enhanced Raman scattering spectroscopy for the quantification of glutathione in whole blood microsamples

Glutathione (GSH) is a non-protein tripeptide thiol that plays a prominent role in oxidative stress defense. GSH concentration is particularly critical in the neonatal period, especially for premature newborns that face increased susceptibility to oxidative stress. Monitoring GSH levels provides valuable insights into newborn health, helping to tailor care to their specific needs. The aim of this study was the development of a sensor specifically targeted for its use in neonatology, enabling GSH determination in only 2 μL of whole blood. The newly developed sensing system simplifies sample processing, addressing a critical need in clinical applications. Unlike current methods that demand fast pre-processing of relatively large sample volumes, expensive equipment, and skilled personnel, the developed approach streamlines the analytical process. By using 2 μL of whole blood, a single syringe filter for sample treatment, a deuterated internal standard (IS) for signal normalization, and Surface Enhanced Raman Scattering (SERS) spectroscopy with a silver colloid substrate for GSH detection, the set-up's characteristics are compatible with point-of-care applications. The analytical procedure was validated and applied to diverse populations including healthy adults (N = 63) and newborns (N = 35), yielding GSH concentration values ranging from 0.6 to 1.8 and 0.8–2.1 mM, respectively. This new optical sensor offers a quick and cost-effective solution to support the assessment of GSH levels in newborns that can greatly benefit not only neonatal care, but also the study of adult populations for health monitoring.

A Vision for the Future of Neutron Scattering and Muon Spectroscopy in the 2050s.

Neutron scattering and muon spectroscopy are techniques that use subatomic particles to understand materials across a wide range of energy (μeV to tens of eV), length (Å to cm) and time (attosecond to hour) scales. The methods are widely used to study condensed phase materials in areas that span physics, chemistry, biology, engineering and cultural heritage. In this Perspective we consider three questions: (i) will neutron scattering and muon spectroscopy still be needed in the 2050s? (ii) What might the technology to produce neutron and muon beams look like in the 2050s? (iii) What will be the applications in the 2050s? Overall, the neutron/muon ecosystem in the 2050s will have less capacity than now, but greater capability because of the somewhat higher power sources, better instrumentation and data analysis.

Velocity And Concentration Measurements Of Supersonic Underexpanded Jets

The release of high-speed gas jets due to a tank leakage can pose a substantial safety hazard, as it can give rise to flammable, explosive, or toxic mixtures. Hence, understanding jet dispersion in real-world conditions is crucial for designing effective safety measures. Existing targeted or traceable studies provide velocity field data, but limitations in source-driven-pressures, nozzle geometries, or cross-flow conditions restrict their representativeness under real conditions. Indeed, an exhaustive experimental dataset for supersonic underexpanded gas jet dispersion under the influence of an Atmospheric Boundary Layer (ABL) is currently lacking. As part of a collaboration with the CEA, the von Karman Institute is continuing research efforts towards the development of high quality nonintrusive, optical measurement techniques for the characterization of the velocity and the concentration of a supersonic underexpanded jet submitted to different cross-flow conditions. The research explicitly targets measurements far from the release point within the self-similar region. Such measurements have already been tried on a supersonic jet without cross-flow and with a uniform velocity low-speed cross-flow [2], but never under the influence of an ABL. By filling this gap, the objective of the present work is to further improve the dispersion characterization by combining different techniques, such as Laser Mie Scattering and Light Extinction Spectroscopy (LES). To evaluate the dispersion within the self-similar region up to x/D ≈ 100, a significant FOV 1 is required. Therefore, Large-Scale Particle Image Velocimetry (LS-PIV) has been adapted and successfully applied to measure the velocity field. Prominent results have been obtained and comparable to standard PIV measurements. The pronounced variation in velocity magnitude observed while transitioning from the potential core to the self-similar region requires collecting multiple datasets to cover the broad spectrum of velocities comprehensively. A Mie scattering theory-based technique has been used to retrieve a relative concentration field. It is a non-intrusive technique that operates on the same experimental images produced by the LS-PIV campaign, assuming that light scattered by particles within a specific volume is proportional to the number of particles within this volume. The algorithm for concentration retrieval was adapted from and consequently improved for the present case. Discrepancies in the scaled concentration evolution among different nozzle diameters highlighted the necessity for refining the technique. This emphasizes accurately determining the reference concentration in a region free from intricate phenomena such as multiple scattering. The absolute and independent concentration measurement is done via Light Extinction Spectroscopy (LES). The LES technique measures the transmittance spectrum T of a collimated light beam passing through the particle-laden flow. This method has successfully been applied to several types of flows with similar seeding particles and concentration quantities (e.g. PSD 2 ). The extrapolation of absolute concentration parameters relies on the regularized solution of an ill-conditioned inverse problem. This solution is derived using the transmittance recorded during the test as the primary input parameter. The system to solve exhibits high sensitivity to small perturbations, making it challenging to employ numerical techniques confidently. Due to the substantial impact of minor perturbations in initial conditions on the system solution, a meticulous adaptation of the technique to the demands of compressible flows is necessary and still ongoing. The setup consists of a Deuterium-Tungsten Halogen UV-NIR light source emitting a divergent beam of light towards a 90◦ off-axis parabolic mirror, which collimates and deviates it into a beam to the jet. After passing through the jet, the resulting attenuated light beam goes into a collector mirror, redirecting it into a composite grating spectrometer UV-NIR with a 200 − 1100 nm wavelength range with 0.5 nm optical resolution. The results will examine the dispersion pattern and feature in terms of velocity and concentration of a supersonic underexpanded jet produced by an upstream tank with total pressure ranging from 5 to 9 bar without cross-flows. The latter will provide a foundation for successive studies on supersonic underexpanded jets subjected to an ABL.

Time-Resolved X-ray Emission Spectroscopy and Resonant Inelastic X-ray Scattering Spectroscopy of Laser Irradiated Carbon.

The existence of liquid carbon as an intermediate phase preceding the formation of novel carbon materials has been a point of contention for several decades. Experimental observation of such a liquid state requires nonthermal melting of solid carbon materials at various laser fluences and pulse properties. Reflectivity experiments performed in the mid-1980s reached opposing conclusions regarding the metallic or insulating properties of the purported liquid state. Time-resolved X-ray absorption studies showed shortening of C-C bonds and increasing diffraction densities, thought to evidence a liquid or glassy carbon state, respectively. Nevertheless, none of these experiments provided information on the electronic structure of the proposed liquid state. Herein, we report the results of time-resolved resonant inelastic X-ray scattering (RIXS) and time-resolved X-ray emission spectroscopy (XES) studies on amorphous carbon (a-C) and ultrananocrystalline diamond (UNCD) as a function of delay time between the irradiating pulse and X-ray probe. For both a-C and UNCD, we attribute decreases in RIXS or XES signals to transition blocking, relaxation, and finally, ablation. Increased signal at 20 ps following the irradiation of the UNCD is attributed to the probable formation of nanoscale structures in the ablation plume. Differences in the amount of signal observed between a-C and UNCD are explained by the difference in sample thickness and, specifically, incomplete melting of the UNCD film. Comparisons to spectral simulations based on MD trajectories at extreme conditions indicate that the carbon state in our experiments is crystalline. Normal mode analysis confirmed that symmetrical bending or stretching of the C-C bonds in the diamond lattice results in XES spectra with small intensity differences. Overall, we observed no evidence of melting to a liquid state, as determined by the lack of changes in the spectral properties for up to 100 ps delays following the melting pulses.

Evaluating the Kinetics and Molecular Mechanism for Biomimetic Metabolic Activation of PAHs by Surface-Enhanced Raman Scattering Spectroscopy.

Biomimetic cytochrome P450 for chemical activation of environmental carcinogens is an efficient in vitro model for evaluating their mutagenicity and ultimately acquiring the metabolites that cannot be easily accessed by conventional routes of organic synthesis. Different kinds of mutagen derived from polyaromatic hydrocarbons (PAHs) by metalloporphyrin/oxidant model systems have been reported, but the underlying molecular mechanisms are poorly understood. Herein, we have for the first time demonstrated an effective surface-enhanced Raman scattering (SERS) protocol to study the dynamics and biomimetic metabolic behaviors of pyrene (Pyr) in the presence of various oxygen donors. Quantitative information on the relative concentration of Pyr and its metabolites in the biomimetic system can be extracted from the SERS spectra. On the basis of our results, we conclude that the oxidative metabolism of Pyr is highly influenced by the types and concentrations of oxygen donors, leading to the formation of 1-hydroxypyrene and dioxygenated products. Besides, the addition of an appropriate amount of an organic solvent can promote the formation of secondary oxidation products. These results offer valuable insights into the dynamics of PAHs metabolism and the regulation of their metabolic pathways in biomimetic activation. In comparison to traditional liquid chromatography-mass spectrometry, the present SERS approach is more suitable for high-throughput evaluation of the metabolic process and kinetics of PAHs. We anticipate that this approach will enable a more general and comprehensive tracking of metabolic dynamics and molecular mechanisms involved in the biomimetic activation of other xenobiotics, such as procarcinogens, promutagens, and drugs.

Detection of Beverage Aspartame Bysurface-Enhanced Raman Scattering Spectroscopy Based on Deep Learning

Detection of Beverage Aspartame Bysurface-Enhanced Raman Scattering Spectroscopy Based on Deep Learning

The Surface of Colloidal Metal-Organic Framework Nanoparticles Revealed by Vibrational Sum Frequency Scattering Spectroscopy.

Solvation shells strongly influence the interfacial chemistry of colloidal systems, from the activity of proteins to the colloidal stability and catalysis of nanoparticles. Despite their fundamental and practical importance, solvation shells have remained largely undetected by spectroscopy. Furthermore, their ability to assemble at complex but realistic interfaces with heterogeneous and rough surfaces remains an open question. Here, we apply vibrational sum frequency scattering spectroscopy (VSFSS), an interface-specific technique, to colloidal nanocrystals with porous metal-organic frameworks (MOFs) as a case study. Due to the porous nature of the solvent-particle boundary, MOF particles challenge conventional models of colloidal and interfacial chemistry. Their multiweek colloidal stability in the absence of conventional surface ligands suggests that stability may arise in part from solvation forces. Spectra of colloidally stable Zn(2-methylimidazolate)2 (ZIF-8) in polar solvents indicate the presence of ordered solvation shells, solvent-metal binding, and spontaneous ordering of organic bridging linkers within the MOF. These findings help explain the unexpected colloidal stability of MOF colloids, while providing a roadmap for applying VSFSS to wide-ranging colloidal nanocrystals in general.

Discriminant analysis of a mixture of pathogenic bacteria into different types and proportions by surface-enhanced Raman scattering spectroscopy combined with chemometric methods

Accurate identification and discrimination of bacteria is crucial for ensuring food safety and reducing pathogenic infections. This study presents a novel approach that combines surface-enhanced Raman scattering spectroscopy (SERS) with chemometric methods for discriminant analysis of a mixture of pathogenic bacteria into different types and proportions. Au@Ag@SiO2 composite nanomaterials were employed as the SERS substrate to collect Raman spectra of multiple pathogenic bacteria. Partial least squares discriminant analysis (PLS-DA) and orthogonal partial least squares discriminant analysis (OPLS-DA) methods were combined with standard normal variate (SNV) to discriminate the different species of mixed bacteria and the multiple proportion mixed bacterial samples, respectively. The results showed that SNV-PLS-DA had good classification performance in the discriminant analysis of different species of mixed bacteria, with an accuracy of 92% for the external test set. Furthermore, both SNV-PLS-DA and SNV-OPLS-DA models exhibited excellent classification performance in the discrimination of multiple pathogenic bacteria at different mixing proportions, achieving 100% accuracy in the external test set, but except for mixed samples of Escherichia coli and Salmonella typhimurium. Our method demonstrates the accurate capability of the SERS platform combined with chemometric methods in the discriminant analysis of multiple pathogenic bacteria at different species and mixing proportions, which provides novel insights for the synchronous analysis of multiple pathogenic bacteria.

Elastic Scattering Spectroscopy on Patient-Selected Lesions Concerning for Skin Cancer.

Access to dermatologists is limited in parts of the US, making primary care clinicians (PCCs) integral for early detection of skin cancers. A handheld device using elastic scattering spectroscopy (ESS) was developed to aid PCCs in their clinical assessment of skin lesions. In this prospective study, 3 PCCs evaluated skin lesions reported by patients as concerning and scanned each lesion with the handheld ESS device. The comparison was pathology results or a 3-dermatologist panel examining high resolution dermatoscopic and clinical images. PCCs reported their diagnosis, management decision, and confidence level for each lesion. Evaluation of results included sensitivity, specificity, negative predictive value (NPV), positive predictive value (PPV), and Area Under the Curve (AUC). A total of 155 patients and 178 lesions were included in the final analysis. The most commonly patient-reported concerning feature was "new or changing lesion" (91.6%). Device diagnostic sensitivity and specificity were 90.0% and 60.7%, respectively, based on biopsy result or dermatologist panel reference standard; comparatively, PCC sensitivity was 40.0% and 84.8% specificity without the use of the device. Device NPV was 98.9%, and device PPV was 13.6%. The device recommended patient referral to dermatology with 88.2% concordance with the dermatologist panel. AUC for the device and PCCs were 0.815 and 0.643, respectively. The use of the ESS device by PCCs can improve diagnostic and management sensitivity for select malignant skin lesions by correctly classifying most benign lesions of patient concern. This may increase skin cancer detection while improving access to specialist care.

Establishment of real-time viral pathogen detection method-surface-enhanced Raman scattering system for porcine circovirus type II

The transition towards large-scale intensive pig farming methods has resulted in an increase in cases of complex, mixed infections, and secondary infections. Porcine circovirus (PCV), the causative agent of PCV disease (PCVD), is a small nonenveloped DNA virus containing a single-stranded circular genome. Previously, PCV was even considered nonpathogenic to pigs. However, a novel strain of PCV, designated PCV-2, has been associated with various disease syndromes in pigs over the last 5 years. PCV-2 primarily induces post-weaning multisystemic wasting syndrome, characterized by clinical signs such as debility, dyspnea, palpable lymphadenopathy, diarrhea, and pallor or icterus. PCV-2 is now recognized as an important emerging pathogen. Early diagnosis and disease prevention have become crucial for effective pig farm management. However, clinical diagnosis may be complicated by antibiotic treatment and atypical disease symptoms. To ensure accurate pathology diagnosis, it is essential to integrate robust laboratory diagnostics with traditional methods. Surface-enhanced Raman Scattering (SERS) spectroscopy has emerged as a potentially powerful technique for whole-organism fingerprinting, enabling rapid identification of bacteria. Biosensors utilizing SERS offer promising capabilities for sensitive and quick detection of bacterial pathogens, thereby reducing diagnosis time. In this study, our aim was to characterize and evaluate a SERS-based diagnostic system for detecting and identifying PCV-2 present in pooled swine sera and feces. We compared the spectra of PCV-2 recovered from the specimens to those of pure PCV-2 to determine the PCV-2 molecular fingerprint. Our results demonstrated successful detection, identification, and classification of PCV-2 in swine sera and feces using SERS. SERS provided reproducible molecular spectroscopic signatures suitable for analytical applications. This approach presents a new and potent tool for real-time surveillance of animal viral pathogens in clinical settings.

Interfacial Bonding Induced Charge Transfer in Two-Dimensional Amorphous MoO3-x/Graphdiyne Oxide Non-Van der Waals Heterostructures for Dominant SERS Enhancement.

Two-dimensional semiconductor-based nanomaterials have shown to be an effective substrate for Surface-enhanced Raman Scattering (SERS) spectroscopy. However, the enhancement factor (EF) tends to be relatively weak compared to that of noble metals and does not allow for trace detection of molecules. In this work, we report the successful preparation of two-dimensional (2D) amorphous non-van der Waals heterostructures MoO3-x/GDYO nanomaterials using supercritical CO2. Due to the synergistic effect of the localized surface plasmon resonance (LSPR) effect and the charge transfer effect, it exhibits excellent SERS performance in the detection of methylene blue (MB) molecules, with a detection limit as low as 10-14 M while the enhancement factor (EF) can reach an impressive 2.55×1011. More importantly, the chemical bond bridging at the MoO3-x/GDYO heterostructures interface can accelerate the electron transfer between the interfaces, and the large number of defective surface structures on the heterostructures surface facilitates the chemisorption of MB molecules. And the charge recombination lifetime can be proved by a ~1.7-fold increase during their interfacial electron-transfer process for MoO3-x/GDYO@MB mixture, achieving highly sensitive SERS detection.