Search Results (7,976)

Raman spectroscopy allows for analyzing local molecular matrix components while preserving spatial resolution in tissue samples. The aim of this study was to use Raman line scans to discriminate between healthy and diseased cartilage tissue based on the depth-dependent sulfated glycosaminoglycans (sGAG) and total GAGs distribution. Full-thickness articular cartilage tissue was harvested from human individuals at different maturation stages (skeletally immature, skeletally mature) and from patients with diagnosed osteoarthritis. Raman spectroscopic line scans (30 µm step size) were utilized to analyze the sub-zonal sGAG (1062 cm⁻¹) and total GAG (1370–1380 cm⁻¹) distribution relative to the organic matrix (CH₂ band 1430–1480 cm⁻¹). We found a linear trend of the sGAG/CH₂ ratio over the tissue depth in all samples (p < 0.0001). The total GAG/CH₂ ratio of the skeletally immature and mature cartilage showed a characteristic non-linear behavior over the tissue distance. The elderly osteoarthritic cartilage exhibited lower total GAG/CH₂ ratios compared to the ratios of the skeletally immature and mature samples, without a pronounced increase in the superficial area. Raman spectroscopic line scans are a fast and representative method allowing us to identify the local and tissue depth-dependent distribution of GAGs at higher specificity and resolution compared to histological staining. Full article

In this study, a new way of protecting textile wearable electronics is proposed. A natural product, silk fibroin, known for its high biocompatibility, biodegradability, and low cytotoxicity, was selected to cover the functionalized fabric to improve its stability and enable washability. Silk fabric was selected as a non-toxic material, suitable for further application on skin and for wearable devices. Silk fabric was functionalized with various amounts of high-pressure carbon monoxide single-walled carbon nanotubes (HiPCO SWNTs). HiPCO SWNTs made the fabric electroconductive, but they are easily washed out of the fabric. The fabric functionalized with HiPCO SWNTs was covered with silk fibroin (SF) protein, which was subsequently crystallized by ethanol vapor to make it insoluble in water. The functionalization and silk fibroin coverage processes were studied using electrical resistance measurements, infrared and Raman spectroscopies, thermogravimetric technique, and surface wettability analysis. The coverage of the fabric with crystallized silk fibroin enables the washing process. The resistance of the functionalized fabric with silk fibroin did not increase significantly. The presented silk fibroin coating can facilitate the construction of future wearable electronics, protect the electroconductive nanomaterials on the fabric surface, and make textile structures reusable. Full article

Hydrogels of acrylamide (AM)–acrylic acid (AA) and nanocomposite hydrogels of AM–AA and carbon nanotubes (CNTs) functionalized with acyl chloride groups (CNTs_OxCl) were synthesized and characterized, and their ability to release folic acid was analyzed. Both hydrogel types were synthesized via redox polymerization. CNTs were prepared via chemical vapor deposition. The prepared samples were analyzed via transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, differential scanning calorimetry, and field-emission scanning electron microscopy. Their swelling ability and their mechanical properties (compression tests) were determined at room temperature ~298.15 K, whereas their ability to release folic acid was studied using UV–VIS spectroscopy. The equilibrium swelling of the AM–AA hydrogels was greater than that of the AM–AA/CNTs_OxCl nanocomposite hydrogels prepared at the same monomeric relation (wt%), whereas the Young moduli of these nanocomposite hydrogels were higher than that of AM–AA hydrogels. For the AM–AA/CNTs_OxCl nanocomposite hydrogels, polymer chains containing AM and AA units were grafted to CNTs_OxCl. The glass–transition temperatures of AM–AA nanocomposite hydrogels were higher than that of AM–AA hydrogels. Folic acid release from the AM–AA hydrogels and AM–AA/CNTs_OxCl nanocomposite hydrogels was successfully adjusted using the Weibull model. Full article

Biosensing plays a vital role in medical diagnostics, environmental monitoring, and food safety, enabling highly sensitive and specific detection of diverse biological and chemical targets. However, conventional biosensing platforms still suffer from limited sensitivity, poor nanoscale resolution, and restricted multiplexed or dynamic detection capabilities. DNA origami, as an emerging bottom-up nanofabrication strategy, enables the construction of programmable nanostructures with high spatial precision. This capability allows the rational arrangement of functional molecules at the nanoscale, thereby offering significant advantages for biosensing applications. Specifically, DNA origami can enhance signal amplification, improve spatial resolution, and enable multiplexed detection under complex conditions. In this review, we provide a systematic overview of recent advances in the application of DNA origami across various classes of biosensors, including microscopy-based biosensors, nanopore biosensors, electrochemical biosensors, fluorescent biosensors, SERS biosensors, and other related biosensors. We aim for this review to advance the development of DNA origami-based biosensing and to provide new insights for researchers working in related fields. Full article

Most biomarkers exhibit abnormal expression in more than one disease, making conventional single-biomarker detection strategies prone to false-negative results. Detecting multiple biomarkers associated with a single disease can therefore substantially improve diagnostic accuracy. Accordingly, recent research has focused on precise multiplex detection, leading to the development of sensors employing various readout methods, including electrochemical, fluorescence, Raman, and colorimetric approaches. This review focuses on optical sensing applications, such as fluorescence, Raman spectroscopy, and colorimetry, which offer rapid and straightforward detection and are well suited for point-of-care testing (POCT). These optical sensors exploit nanoscale phenomena derived from the intrinsic properties of nanomaterials, including metal-enhanced fluorescence (MEF), Förster resonance energy transfer (FRET), and surface-enhanced Raman scattering (SERS), which can be tailored through modifications in material type and structure. We summarize the types and properties of commonly used nanomaterials, including plasmonic and carbon-based nanoparticles, and provide a comprehensive overview of recent advances in multiplex biomarker detection. Furthermore, we address the potential of these nanosensors for clinical translation and POCT applications, highlighting their relevance for next-generation disease diagnostic platforms. Full article

Poly(5-indolylboronic acid) was synthesized electrochemically via cyclic voltammetry using various electrodes, including screen-printed carbon electrodes, glassy carbon electrodes, highly oriented pyrolytic graphite, and 304 stainless steel. This study provides a thorough analysis of the resulting conducting polymer’s electrochemical behavior, morphological and structural characteristics, and potential applications. The following techniques were employed: cyclic voltammetry, electrochemical impedance spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and field-emission scanning electron microscopy. The polymer exhibits pH-dependent redox activity within the pH range of 4–10, displaying Nernstian behavior and achieving a specific areal capacitance of 0.234 mF∙cm⁻² on an SPCE electrode. This result highlights the electrode’s efficiency in terms of charge storage. Impedance data indicate that the modified electrodes demonstrate a substantial decrease in charge transfer resistance and improved interfacial conductivity compared to bare electrodes. Contact angle measurements show that the presence of boronic acid groups makes the polymer hydrophilic. However, when 5PIBA was incubated in the presence of molecules containing hydroxyl groups or certain proteins, such as casein, no adsorption was observed. This suggests limited interaction with functional groups such as amino, hydroxide, and carboxyl groups present in these molecules, indicating the potential application of the polymer in biocorrosion. 5PIBA forms homogeneous, stable, and electroactive coatings on various substrates, making it a promising and versatile material for electrochemical technologies, and paving the way for future functionalization strategies. Full article

Searching anode materials is an important task for the development of sodium-ion batteries. In this regard, bronze-phase titanium dioxide, TiO₂(B), has been considered as one of the promising materials, owing to its crystal structure with open channels and voids facilitating Na⁺ diffusion and storage. However, the electrochemical de-/sodiation mechanism of TiO₂(B) has not been clearly comprehended, and further experiments are required. Herein, in situ and ex situ observations by a combination of X-ray photoelectron spectroscopy, X-ray diffraction, Raman spectroscopy, gas chromatography–mass spectrometry was used to provide additional insights into the electrochemical reaction scenario of bronze-phase TiO₂ in Na-ion batteries. The findings reveal that de-/sodiation of TiO₂(B) occurs through a reversible intercalation reaction and without the involvement of the conversion reaction (no metallic titanium is formed and no oxygen is released). At the same time, upon the first Na⁺ uptake process, crystalline TiO₂(B) becomes partially amorphous, but is still driven by the Ti⁴⁺/Ti³⁺ redox couple. Importantly, TiO₂(B) has pseudocapacitive electrochemical behavior during de-/sodiation based on a quantitative analysis of the cyclic voltammetry data. The results obtained in this study complement existing insights into the sodium storage mechanisms of TiO₂(B) and provide useful knowledge for further improving its anode performance for SIBs application. Full article

Foodborne pathogenic bacteria in meat pose a serious threat to human health. Traditional detection methods for these bacteria are often time-consuming and labor-intensive. In this study, we applied surface-enhanced Raman scattering (SERS) combined with portable Raman spectroscopy as a rapid and convenient detection technique. SERS is a sensitive and fast method that enhances light scattering on rough metal surfaces. Silver nanoparticles (AgNPs) were used as SERS substrates to identify and analyze four pathogenic bacteria, including Escherichia coli (E. coli) O157:H7, Salmonella typhimurium (S. typhimurium), Staphylococcus aureus (S. aureus), and Listeria monocytogenes (L. monocytogenes), in beef. We optimized the detection conditions of AgNPs and established the limit of detection (LOD) for these four pathogenic bacteria in both pure culture and beef samples. The LODs were as low as 4–23 CFU/mL in beef samples, indicating high detection sensitivity. Linear discriminant analysis (LDA) was used to analyze the SERS spectra, yielding an accuracy of 91.7–97.3%. This study not only provides a rapid and portable detection method for pathogenic bacteria in beef but also overcomes the limitations of traditional methods that are often time-consuming and not suitable for on-site detection. However, the current study is limited to the detection of the four specific pathogenic bacteria, and further research is needed to expand the range of detectable pathogens and to improve the robustness of the detection models for more complex meat samples. Overall, this research demonstrates the potential of SERS combined with portable Raman spectroscopy as a powerful tool for the rapid detection of pathogenic bacteria in meat products, which could significantly enhance food safety monitoring and control. Full article

In this work, diamond/Si heterojunctions were fabricated by synthesizing a diamond layer directly on a monocrystalline n-type Si substrate. The diamond layers were characterized using micro-Raman spectroscopy, scanning electron microscopy (SEM), and X-ray diffraction (XRD). The current–voltage (I–V) characteristics of the heterojunctions were measured at room temperature. The heterojunctions exhibited rectifying behavior, confirming their diode-like nature. Based on thermionic emission theory, key electrical parameters of the heterojunction diodes—including the ideality factor (n) and carrier mobility (μ)—were estimated from the I–V characteristics. The I–V curves revealed large ideality factors ranging from 1.5 to 6.5, indicating the presence of deep trap states with densities between 2 × 10¹⁵ and 8 × 10¹⁶ eV⁻¹·cm⁻³. These variations were attributed to differences in the structural quality of the diamond layers and the effects of surface hydrogen termination. Full article

This study presents a comprehensive morphological and structural analysis of carbon materials produced via simple thermal methane pyrolysis conducted under laboratory conditions in a quartz reactor without the use of catalysts. The process, carried out at 1000 °C, achieved moderate methane conversion (36.5%), process efficiency (36.1%), and very high selectivity (98.9%) towards hydrogen production, highlighting its potential as a CO₂-free hydrogen generation method. Distinct carbon morphologies were observed depending on the formation areas within the reactor: a predominant flake-like silver carbon formed on reactor walls at temperatures between 600 and 980 °C (accounting for 91% of the solid product) and a minor powdery carbon formed near 980–1000 °C (9% of the solids). The powdery carbon exhibited a high specific surface area (125.3 m²/g), substantial mesoporosity (60%), and porous spherical aggregates, indicating an amorphous structure. In contrast, flake-like carbon demonstrated a low surface area (1.99 m²/g), high structural order confirmed by Raman spectroscopy, and superior thermal stability, making it suitable for advanced applications requiring mechanical robustness. Additionally, polycyclic aromatic hydrocarbons were detected in cooler zones of the reactor, suggesting side reactions in low-temperature areas. The study underscores the impact of temperature zones on carbon structure and properties, emphasizing the importance of precise thermal control to tailor carbon materials for diverse industrial applications while producing clean hydrogen. Full article

Autoimmune diseases constitute a broadly prevalent category of disorders. Conventional computer-aided diagnostic (CAD) techniques rely on large volumes of data paired with reliable annotations. However, the diverse symptomatology and diagnostic complexity of autoimmune diseases result in a scarcity of reliably labeled biological samples. In this study, we propose a pseudo-label-based conditional domain adversarial network (CDAN-PL) framework by integrating Raman spectroscopy with domain adaptation technology, enabling label-free unsupervised transfer diagnosis of diseases. Compared to traditional unsupervised domain adaptation techniques, our CDAN-PL framework generates reliable pseudo-labels to ensure the robust implementation of conditional adversarial methods. Additionally, its spectral data-adaptive feature extraction techniques further solidify the model’s superiority in Raman spectroscopy-based disease diagnosis. CDAN-PL exhibits excellent performance in homologous transfer tasks, achieving an average accuracy of 92.3%—surpassing the baseline models’ 80.81% and 86.4%. Moreover, it attains an average accuracy of 90.05% in non-homologous transfer tasks, further validating its generalization capability. Full article

The photocatalytic efficiency of TiO₂ was significantly enhanced by coupling with WO₃ to form a TiO₂/WO₃ heterostructure, designed to operate effectively under UV-LED irradiation. The nanocomposites were synthesized via a hydrothermal route, and their activity was evaluated through the degradation of the pharmaceutical pollutant venlafaxine. Contaminants are rarely addressed in photocatalytic studies. Unlike a simple physical mixture of commercial TiO₂ and WO₃ powders, the hydrothermally synthesized TiO₂/WO₃ photocatalyst exhibited superior efficiency, attributable to its nanoscale dimensions achieved via the hydrothermal route, which promoted improved charge carrier separation, enhanced surface homogeneity, and the formation of an effective heterojunction interface. An optimization study varying the WO₃ content (5, 10, 20, and 30 wt.%) within the TiO₂ revealed that the 10 wt.% WO₃ composition achieved the highest performance, with ~52% venlafaxine degradation within 60 min. SEM, TEM, FTIR, Raman spectroscopy, XRD, and UV-Vis DRS revealed the successful incorporation of WO3 into the TiO₂ matrix, confirming phase purity and composition-dependent structural evolution of the nanocomposite, and evidencing extended light absorption and superior charge-transfer properties. Importantly, the optimized photocatalyst thin film retained excellent stability and reusability, maintaining high degradation efficiency over three consecutive cycles with negligible activity loss, which avoids slurry separation. These findings establish hydrothermally synthesized TiO₂/10%WO₃ thin film heterostructures as effective and sustainable photocatalytic platforms for the removal of pharmaceutical pollutants in wastewater under UV-LED irradiation. Full article

With the development of technology, many fields have put forward higher requirements for the thermal conductivity of materials in high-temperature environments, for instance, in fields such as heat dissipation of electronic devices, high-temperature sensors, and thermal management. As a potential high-performance thermal management material, studying the thermal conductivity of graphene at high temperatures is of great significance for expanding its application range. In this study, high-quality suspended graphene was prepared through PDMS dry transfer, which can effectively avoid the binding and influence of the substrate. Based on the calculation model of the thermal conductivity of suspended graphene, the model was modified accordingly by measuring the attenuation coefficient of laser power. Combined with the temperature variation coefficient of suspended graphene measured experimentally and the influence of laser power on the Raman characteristic peak positions of graphene, the thermal conductance of suspended graphene with different layers under high-temperature conditions was calculated. It is conducive to a further in-depth understanding of the phonon scattering mechanism and heat conduction process of graphene at high temperatures. Full article

Two gold-decorated wooden sculptures of Qing Dynasty collected in Qianjiang Cultural Administration Institute, Chongqing, China, holds significant cultural value. Although in appearance they were preserved completely, the wooden bodies exhibited a certain degree of decay with severe peeling of the surface painted layer and gold lacquer layer. In this study, the samples from the sculptures were characterized by microscopy, SED–EDS (Scanning Electron Microscopy and Energy Dispersive Spectrometer) analysis, and Raman spectroscopy, while the preservation state of wooden core was assessed through the fluorescence microscopy and NREL (National Renewable Energy Laboratory) chemical analysis methods. Findings reveal that the raw material for wooden sculpture is cypress, and holocellulose content of wooden core is as low as 32%. The raw materials for red pigment include cinnabar (HgS) and hematite (Fe₂O₃). There are multiple layers of lacquer and gold can be observed. There is a layer made of clay, gypsum, or brick ash beneath the lacquer layer and colored layer. The gold layer on the surface adopted traditional Chinese gilding technique which is called sticking gold. This study provides insights into the material properties and technological features of these wooden sculptures, offering a reference for future protection of similar sculptures. Full article

In situ high-temperature Raman spectroscopy (up to 550 °C) and infrared spectroscopy (up to 700 °C) were employed to analyze hydrous Fe-rich ringwoodite (Fo76 composition containing 0.69 wt% H₂O). The results demonstrate that the hydrous Fe-rich ringwoodite sample undergoes irreversible structural transformation above 300 °C at ambient pressure, converting to an amorphous phase. This indicates a lower thermal stability threshold compared to Fe-bearing ringwoodite (Fo90) with equivalent water content. Notably, identical infrared spectral evolution patterns were observed during heating (25–500 °C) for the studied Fo76 sample and previously reported Fo82/Fo90 specimens, suggesting minimal influence of iron content variation on hydroxyl group behavior. The material derived from Fe-rich ringwoodite through structural transformation at ~350 °C retains the capacity to preserve water within a defined temperature window (400–550 °C). In situ high-pressure Raman spectroscopy experiments conducted up to 20 GPa detected no notable structural modifications, suggesting that hydrous Fe-rich ringwoodite, hydrous Fe-bearing ringwoodite, and hydrous Mg-endmember ringwoodite exhibit comparable structural stability within this pressure range. Full article