Search Results (330)

1,3-Diphenylisobenzofuran (DPBF) is a widely used fluorescent probe for singlet oxygen (¹O₂) detection in photodynamic applications. In this work, we present an integrated experimental and computational analysis to describe its spectroscopic, photophysical, and reactive properties in ethanol, DMSO, and DMF. UV-Vis and fluorescence measurements across a wide concentration range show well-resolved S₀ → S₁ electronic transition of a π → π* nature with small red shifts in polar aprotic solvents. Fluorescence lifetimes increase slightly with solvent polarity, showing stabilization of the excited state. The 2D PES and Boltzmann populations analysis indicate two co-existing conformers (C_s and C₂), with C_s being slightly more stable at room temperature. TD-DFT calculations have been performed using several density functionals and the 6-311+G(2d,p) basis set to calculate absorption/emission wavelengths, oscillator strengths, transition dipole moments, and radiative lifetimes. Overall, cam-B3LYP and ωB97X-D provided the best agreement with experiments for the photophysical data across all solvents. The photophysical behavior of DPBF upon interaction with ¹O₂ can be explained by a small-barrier, two-step reaction pathway that goes through a zwitterionic intermediate, resulting in the formation of 2,5-endoperoxide. This work explains the photophysical properties and reactivity of DPBF, therefore providing a solid basis for future studies involving singlet oxygen. Full article

The detection of Fe²⁺ in environmental water sources is critical due to its biological relevance and potential toxicity at elevated levels. Herein, we report a plasmon-driven catalytic sensing nanoplatform based on p-aminothiophenol (pATP)-functionalized silver nanoparticles (AgNPs) for the selective and sensitive detection of Fe²⁺. The nanoplatform exploits the inhibition of the plasmon-driven catalytic conversion of pATP to 4,4-dimercaptoazobenzene (DMAB), monitored via surface-enhanced Raman scattering (SERS) spectroscopy. The catalytic efficiency was quantified by the intensity ratio between the formed DMAB-specific Raman band and the common aromatic ring vibration band of pATP and DMAB. This ratio decreased proportionally with increasing Fe²⁺ concentration over a range of 100 µM to 1.5 mM, with a calculated limit of detection of 39.7 µM. High selectivity was demonstrated against common metal ions, and excellent recovery rates (96.6–99.4%) were obtained in real water samples. Mechanistic insights, supported by chronopotentiometric measurements under light irradiation, revealed a competitive oxidation pathway in which Fe²⁺ preferentially consumes plasmon-generated hot holes over pATP. This mechanism clarifies the observed catalytic inhibition and supports the design of redox-responsive SERS sensors. The platform offers a rapid, low-cost, and portable solution for Fe²⁺ monitoring and holds promise for broader applications in detecting other redox-active analytes in complex environmental matrices. Full article

Retinal degenerative processes such as age-related macular degeneration are at the center of many ongoing research studies, as their impact on the general population is significant, with severe visual impairment and even irreversible vision loss if left untreated. Currently, there are few efficient treatments available to stop or limit its progression. In the present paper, a molecular hybridization approach was employed to develop novel compounds that address this issue. By adding either 2-butenal or a β-ionone-derived residue to the hydrazone-catechol-thiazole scaffold, two compounds were designed and synthesized: 5a and 5b. After being characterized by mass spectrometry and nuclear magnetic resonance, and proving potent antioxidant activity in the in vitro assays, the cytotoxicity evaluation using the ARPE-19, BJ, and A549 cell lines revealed a surprisingly low-dose effect of 5a and the unexpected cytotoxic activity of 5b, despite its β-ionone moiety, known for its significant therapeutic properties. Full article

The Po Nagar Towers (Thap Ba) complex, an iconic heritage site of Cham culture and a nationally recognized special relic, has stood in Nhatrang, Vietnam, for over a thousand years. We report here a preliminary analysis of original ancient Cham bricks from the Po Nagar Towers using a combination of appropriate characterization techniques, including X-ray fluorescence (XRF), X-ray diffraction (XRD), Raman micro-spectroscopy, thermal dilatometry, compressive strength testing, and water sorption. Mechanical properties and firing temperatures of the ancient bricks have been determined to support the discussion on the likely technology used to make them. Specifically, they were made from clay, sand, plagioclases/feldspar, and grog mixed with intentionally added carbon precursor (charcoal powder), then fired at temperatures between 800 °C and 1000 °C to form lightweight bricks with a mass density of 1.3–1.6 kg/dm³ and an open porosity of 18–25%. The ancient Cham bricks have their texture and porosity to meet the requirements of the thin rubbing joint technique in tower construction and to contribute to the carvability and durability of Cham towers. A comparison is made with the bricks for tower restoration during the 2000s. Full article

The growing global demand for phytochemicals as bioactive sources is prompting scientists to develop methods that link their sensory properties to their mechanisms of action in cancer treatment. Recent techniques for tracking the actions of small plant metabolites (SPMs) from single-cell plant sources to their molecular anticancer biomarkers could provide valuable insights in this field. Among the critical methods discussed in this review are the real-time tracking of cell components through stable isotope probing (Sis) and microspectroscopy, which has attracted the attention of biotechnologists. Additionally, the precise pathways required for studying new insights into functional materials are discussed, based on high-resolution and accurate technologies, which could aid their functional categorization. Notably, the molecules under study have recently garnered attention for their anticancer applications due to advancements in effective evaluation techniques that surpass traditional methods. In December 2020, the Food and Drug Administration (FDA) authorized 89 SPMs as safe anticancer natural molecules. In conclusion, by combining spatiotemporal techniques and SPMs’ mechanisms, they could facilitate the development of more exceptional, bio-efficient materials. Full article

Raman microspectroscopy is a powerful, label-free technique for the biochemical characterization of cells, but its complex spectral data require advanced computational methods for meaningful interpretation. Clustering analysis is widely used in spectroscopic imaging to extract meaningful biochemical information. Traditional methods, such as K-means clustering with Euclidean distance, often struggle to capture subtle spectral variations, leading to suboptimal segmentation. Alternative distance metrics, including cosine and Mahalanobis distances, have been explored to enhance cluster separability, yet challenges remain in distinguishing chemically relevant features while minimizing redundancy and noise. In this study, we introduce an asymmetric metric distance matrix with a tunable eccentricity parameter to improve clustering performance in Raman hyperspectral imaging. Our results demonstrate that suitable eccentricity values enhance the identification of subcellular structures while requiring fewer clusters than Euclidean-based approaches. Compared to polar metrics, the proposed asymmetric metric achieves better stability and reduced noise, leading to more accurate segmentation. Future research could explore its application in other clustering techniques and machine learning frameworks, as well as its application in broader spectral imaging techniques where the distance metric plays a fundamental role. Full article

Background/Objectives: Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer, with diverse clinical presentations. This study aims to correlate findings from dermoscopy, ultrasonography, ex vivo confocal microscopy, and histology to improve diagnostic accuracy and guide better clinical management of cSCC. Methods: This cross-sectional study, conducted between July 2022 and December 2024, included 26 patients with 35 clinically suspicious cSCC tumors, analyzed through clinical, dermoscopic, high-frequency ultrasound (HFUS), ex vivo confocal fluorescence microscopy (FCM), and histopathology. Tumors were evaluated for various clinical, imaging, and histopathological criteria, such as tumor thickness, vascularization, differentiation degree, and invasion level, with FCM applied to 24 tumors for advanced microscopic analysis. Results: The study analyzed 35 cases of histopathologically confirmed cSCC, finding that invasive SCC was associated with greater tumor thickness, increased vascularization, and ulceration on both ultrasound and dermatoscopy, while in situ SCC showed homogeneous echogenicity and specific dermoscopic patterns like dotted vessels and white halos. Strong correlations were identified between ultrasound and histopathological measurements of tumor thickness and invasion depth, and confocal microscopy revealed that features like plump bright cells and nest-like structures were linked to invasive and poorly differentiated tumors. Conclusions: This study uniquely integrates advanced imaging techniques—dermatoscopy, skin ultrasound, and ex vivo confocal microscopy—with histopathological analysis to provide new insights into tumor grade, vascularity, and invasion depth in cSCC, enhancing non-invasive diagnosis. Full article

The reflectance (R) of linear and circular micro-gratings on c-plane sapphire Al₂O₃ ablated by a femtosecond (fs) laser were spectrally characterised for thermal emission $\propto (1-R)$ in the mid-to-far infrared (IR) spectral range. An IR camera was used to determine the blackbody radiation temperature from laser-patterned regions, which showed (3–6)% larger emissivity dependent on the grating pattern. The azimuthal emission curve closely followed the Lambertian angular profile $\propto cos{\theta }_a$ at the 7.5–13 μm emission band. The back-side ablation method on transparent substrates was employed to prevent debris formation during energy deposition as it applies a forward pressure of >0.3 GPa to the debris and molten skin layer. The back-side ablation maximises energy deposition at the exit interface where the transition occurs from the high-to-low refractive index. Phononic absorption in the Reststrahlen region 20–30 μm can be tailored with the fs laser inscription of sensor structures/gratings. Full article

Humans are constantly exposed to low doses and low-dose rates of ionizing radiation from both natural and man-made sources. For this reason, there is a growing interest in studies on the biological effects of low-dose radiation. Vibrational spectroscopies, such as Fourier transform infrared and Raman micro-spectroscopies, have been fruitfully employed for studying the effects of high doses of ionizing radiation on biosystems. Aiming at clarifying the potential of the above-mentioned spectroscopic techniques to monitor the changes induced in cells, tissues, and other biological samples by low doses of ionizing radiations, we report a review of the literature in this research field. The analysis of published results suggests that vibrational spectroscopies make a valuable contribution. Additional and more systematic investigations could help to fully exploit the capabilities of these spectroscopic techniques. Full article

Objectives: This scoping review aimed to provide both researchers and practitioners with an overview of how machine learning (ML) methods are applied to infrared spectroscopy for the diagnosis and prognosis of head and neck precancer and cancer. Methods: A subject headings and keywords search was conducted in MEDLINE, Embase, and Scopus on 14 January 2024, using predefined search algorithms targeting studies that integrated infrared spectroscopy and ML methods in head and neck precancer/cancer research. The results were managed through the COVIDENCE systematic review platform. Results: Fourteen studies met the eligibility criteria, which were defined by IR spectroscopy techniques, ML methodology, and a focus on head and neck precancer/cancer research involving human subjects. The IR spectroscopy techniques used in these studies included Fourier transform infrared (FTIR) spectroscopy and imaging, attenuated total reflection-FTIR, near-infrared spectroscopy, and synchrotron-based infrared microspectroscopy. The investigated human biospecimens included tissues, exfoliated cells, saliva, plasma, and urine samples. ML methods applied in the studies included linear discriminant analysis (LDA), principal component analysis with LDA, partial least squares discriminant analysis, orthogonal partial least squares discriminant analysis, support vector machine, extreme gradient boosting, canonical variate analysis, and deep reinforcement neural network. For oral cancer diagnosis applications, the highest sensitivity and specificity were reported to be 100%, the highest accuracy was reported to be 95–96%, and the highest area under the curve score was reported to be 0.99. For oral precancer prognosis applications, the highest sensitivity and specificity were reported to be 84% and 79%, respectively. Conclusions: This review highlights the promising potential of integrating infrared spectroscopy with ML methods for diagnosing and prognosticating head and neck precancer and cancer. However, the limited sample sizes in existing studies restrict generalizability of the study findings. Future research should prioritize larger datasets and the development of advanced ML models to enhance reliability and robustness of these tools. Full article

Polyamorphic transitions driven by high-energy mechanical milling (nanomilling) are studied in thioarsenide As₄Se_n-type glassy alloys obtained by melt quenching deviated from arsenic triselenide As₂Se₃ stoichiometry towards tetraarsenic pentaselenide (g-As₄Se₅) and tetraarsenic tetraselenide (g-As₄Se₄). This employs a multiexperimental approach based on powder X-ray diffraction (XRD) analysis complemented by thermophysical heat transfer, micro-Raman scattering (micro-RS) spectroscopy, and revised positron annihilation lifetime (PAL) analysis. Microstructure scenarios of these nanomilling-driven transformations in arsenoselenides are identified by quantum-chemical modeling using the authorized modeling code CINCA (the Cation Interlinked Network Cluster Approach). A straightforward interpretation of a medium-range structure response of a nanomilling-driven polyamorphism in the arsenoselenides is developed within the modified microcrystalline model. Within this model, the diffuse peak-halos arrangement in the XRD patterning is treated as a superposition of the Bragg-diffraction contribution from inter-planar correlations supplemented by the Ehrenfest-diffraction contribution from inter-atomic (inter-molecular) correlations related to derivatives of network As₂Se₃-type and molecular As₄Se₄-type conformations. Changes in the medium-range structure of examined glassy arsenoselenides subjected to nanomilling occur as an interplay between disrupted intermediate-range ordering and enhanced extended-range ordering. The domination of network-forming conformations in arsenoselenides deviated from As₂Se₃ stoichiometry (such as g-As₄Se₅) results in rather slight changes in their calorimetric heat-transfer and micro-RS responses. At the atomic-deficient level probed by PAL spectroscopy, these changes are accompanied by reduced positron trapping rate of agglomerated multiatomic vacancies and vacancy-type clusters in an amorphous As-Se network. Under an increase in As content beyond the g-As₄Se₅ composition approaching g-As₄Se₄, nanomilling-driven polyamorphic transitions, which can be classified as reamorphization (amorphous I-to-amorphous II) phase transitions, are essentially enhanced due to the higher molecularity of these glassy alloys enriched in thioarsenide-type As₄Se₄ cage-like molecular entities and their low-order network-forming derivatives. Full article

Amazonian fruit residues like piquia shells are often discarded despite their antioxidant potential for sustainable cosmetic use. This study evaluated the photostability, phototoxicity, and photoprotection of hydroalcoholic piquia shell extract (PqSE) combined with UV filters in solutions and cosmetic formulations. PqSE formulations were photostable, even stabilizing photounstable UV filters. Phototoxicity tests (OECD TG 432) showed no phototoxic potential (MPE < 0.15) and reduction in the phototoxic potential of UV filters, while ocular irritation potential via HET-CAM assay indicated no irritant effects. The extract combined with UV filters enhanced protection against UVA-induced reactive oxygen species (ROS) production, achieving 60.9% effectiveness, outperforming commercial photostabilizers. Against UVB radiation, it showed cellular viability above 80%, comparable to benzophenone-3. PqSE formulations exhibited a radical protection factor (RPF) nine times higher than controls and reduced radical production by 64% after visible/near-infrared (VIS/NIR) irradiation on porcine skin, compared to 38% for controls. Confocal Raman microspectroscopy showed penetration depths below 12 µm for all time points. This study highlights the potential of reusing fruit residues like PqSE as sustainable, effective ingredients in sunscreen formulations, offering enhanced photoprotection and reduced environmental waste. Full article

X-ray radiation treatments are largely adopted in radiotherapy, and Fourier-transform infrared microspectroscopy (μ-FTIR) has already been demonstrated to be a useful instrument for monitoring radiotherapy effects. Previous works in this field have focused on studying the changes occurring in cells when they are fixed immediately after the irradiation or 24 and 48 h later. In the present paper, changes occurring in SH-SY5Y neuroblastoma cells in the first hours after the irradiation are examined to obtain information on the processes taking place in this not-yet-investigated time window by using μ-FTIR. For this purpose, cell samples were fixed immediately after X-ray exposure, and 2 and 4 h after irradiation and investigated along with unexposed cells. Different data analysis procedures were implemented to estimate the changes in lipid, protein, and DNA spectral contributions. The present investigation on the effects of X-ray in the first hours after the exposure is helpful for better describing the processes occurring in this time window that offer the possibility of a timely check on the efficacy of X-ray treatments and can potentially be applied for planning personalized treatment as required by the most advanced medical therapy. Full article

A novel double-impurity doping process for silicon (Si) surfaces was developed, utilizing nanosecond-laser melting of an 11 nm thick gold (Au) top film and a Si wafer substrate in a laser plasma-activated liquid nitrogen (LN) environment. Scanning electron microscopy revealed a fluence- and exposure-independent surface micro-spike topography, while energy-dispersive X-ray spectroscopy identified minor Au (~0.05 at. %) and major N (~1–2 at. %) dopants localized within a 0.5 μm thick surface layer and the slight surface post-oxidation of the micro-relief (oxygen (O), ~1.5–2.5 at. %). X-ray photoelectron spectroscopy was used to identify the bound surface (SiN_x) and bulk doping chemical states of the introduced nitrogen (~10 at. %) and the metallic (<0.01 at. %) and cluster (<0.1 at. %) forms of the gold dopant, and it was used to evaluate their depth distributions, which were strongly affected by the competition between gold dopants due to their marginal local concentrations and the other more abundant dopants (N, O). In this study, 532 nm Raman microspectroscopy indicated a slight reduction in the crystalline order revealed in the second-order Si phonon band; the tensile stresses or nanoscale dimensions of the resolidified Si nano-crystallites envisioned by the main Si optical–phonon peak; a negligible a-Si abundance; and a low-wavenumber peak of the Si₃N₄ structure. In contrast, Fourier transform infrared (FT-IR) reflectance and transmittance studies exhibited only broad structureless absorption bands in the range of 600–5500 cm⁻¹ related to dopant absorption and light trapping in the surface micro-relief. The room-temperature electrical characteristics of the laser double-doped Si layer—a high carrier mobility of 1050 cm²/Vs and background carrier sheet concentration of ~2 × 10¹⁰ cm⁻² (bulk concentration ~10¹⁴–10¹⁵ cm⁻³)—are superior to previously reported parameters of similar nitrogen-implanted/annealed Si samples. This novel facile double-element laser-doping procedure paves the way to local maskless on-demand introductions of multiple intra-gap intermediate donor and acceptor bands in Si, providing related multi-wavelength IR photoconductivity for optoelectronic applications. Full article

The stratum corneum (SC) forms the outermost layer of the skin, playing a critical role in preventing water loss and protecting against external biological and chemical threats. Approximately 90% of the SC consists of large, flat corneocytes, yet its barrier function primarily relies on the intercellular lipid matrix that surrounds these cells. Traditional methods for characterizing these lipids, such as Fourier transform infrared spectroscopy (FTIR), typically involve macroscopic analysis using attenuated total reflection (ATR) techniques. In this study, we introduce a novel approach for investigating SC samples at a microscopic level to gain detailed chemical insights and assess sample heterogeneity. Special emphasis is placed on advanced hyperspectral data pre-processing to ensure the accuracy and reliability of the results. We also evaluate methods for filtering out spectral data that significantly deviate from the mean and analyze the extracted mean spectra, the intensities of specific infrared peaks, and their ratios. The novelty of this work lies in its microscopic approach to analyzing the SC lipid matrix, diverging from the traditional macroscopic FTIR–ATR methods. By focusing on hyperspectral imaging and developing robust pre-processing techniques, this study provides more localized, high-resolution chemical insights. This microscopic perspective opens up the possibility of detecting subtle heterogeneities within the skin’s lipid matrix, offering deeper, previously unattainable understanding of the SC’s barrier function. Additionally, the exploration of spectral filtering methods enhances the precision of the analysis, paving the way for more refined and reliable investigations of skin structure and behavior in future research. Full article