Surface-Enhanced Raman Spectroscopy (SERS) has emerged as a highly promising technique for trace-level molecular detection due to its unique ability to amplify Raman signals via localized surface plasmon resonance (LSPR). However, practical SERS applications face critical challenges, including poor signal reproducibility, non-uniform hotspot distribution, and fabrication complexity that limits scalability. Addressing these limitations, this study presents the rational design and development of a plasmonic gold nanodisk array as a highly uniform and tunable SERS substrate. The primary objective was to fabricate a reproducible, scalable, and optically optimized nanostructure capable of delivering high electromagnetic enhancement and consistent Raman response across large surface areas. The gold nanodisk arrays were fabricated using nanosphere lithography and characterized by SEM and AFM for structural verification. FDTD simulations were employed to optimize disk dimensions for maximum field enhancement near the 785 nm excitation wavelength. Experimental SERS measurements using Rhodamine 6G and 4-MBA confirmed enhancement factors exceeding 10 7 , with a detection limit down to 10 -9 M. Raman mapping demonstrated a spatial coefficient of variation below 8%, indicating excellent uniformity. Additionally, real-time biosensing was validated using Bovine Serum Albumin in a microfluidic system, showing reversible signal kinetics and sensor regenerability. These findings confirm the gold nanodisk array as a high-performance SERS substrate offering sensitivity, reproducibility, and integration compatibility, thereby addressing key obstacles to widespread SERS implementation in biomedical and environmental diagnostics.

Microplastic (MP) pollutes our terrestrial and aquatic ecosystems due to their uncontrolled discharge into our environment. The analysis of MP contamination is still a challenge, although significant improvements are made for different environmental matrices. Using mass-based particle analysis methods such as thermal extraction and desorption-gas chromatography/mass spectroscopy (GC/MS) or pyrolysis GC/MS, essential parameters such as the MP's morphology, size, and shape cannot be obtained, which are indispensable to assess the hazard of the respective particles. Raman, micro-Fourier transform infrared, and attenuated total reflectance spectroscopy are particle-based analysis methods, which are time-consuming due to the high purification effort. Thus, novel, reliable, and time-efficient methods for MP analysis are required. Previously, studies showed the potential of frequency domain fluorescence lifetime imaging microscopy (FD-FLIM) to identify plastics' type, shape, size, and morphology, and distinguishing these from natural materials. However, only pure plastic granules were investigated, omitting that commodity plastics accumulating in our environment contain various additive, filler, or dye concentrations. To circumvent the dependency of additive, filler, and dye concentrations, we investigated the fluorescence spectra and lifetimes of three plastic types, individually composed with two fillers, three additives, and two dyes in six different concentrations. We heuristically modeled the dependency of the concentration on plastics' fluorescence lifetime using a logarithmic model with a high correlation and showed that identifying the plastic types is hardly possible when fillers, additives, or dyes are added in various concentrations because of their superimposing fluorescence lifetimes. However, further research has to be conducted to investigate different emission states of fluorescence to optimize the FD-FLIM method, as only one excitation wavelength and emission band was used for the investigations.

New automatic fluorescence monitoring system for insecticides in surface and groundwater. Applications to pyrethroids in the Niayes agricultural area of Senegal.

Investigation of the histone deacetylase inhibitor potential of phorbazole analogues.

Dual-signal fluorescence and colorimetric sensor based on N,P co-doped carbon dots for selective detection of doxycycline.

Preparation of a fluorescent sensor for fast and highly sensitive detection of patulin using a polyvinylpyrrolidone-modified UiO-66 metal-organic framework.

Tyrosinase, encoded by Tyr, is a key rate-limiting enzyme in melanin biosynthesis. Knockout of Tyr results in a distinct albino phenotype, making it a widely used target for evaluating gene-editing efficiency. Here, we found that the tyrosinase-deficient skin melanophore lineage of Xenopus tropicalis (X. tropicalis) tadpoles shows strong autofluorescence under the GFP filter, which may interfere with in vivo fluorescence imaging. Through spectral scanning analysis, we characterized the emission spectrum of the autofluorescence under commonly used excitation wavelengths for fluorescent proteins. Based on this, we established a reference protocol for identifying and excluding such interference in Tyr-targeted knockin studies. Furthermore, knockout of the GTP cyclohydrolase 2 gene (Gch2) using CRISPR-Cas9 significantly reduced the fluorescence intensity induced by tyrosinase deficiency, indicating an essential role of the enzyme and its mediated pterine biosynthesis in the generation of the autofluorescence. This study systematically characterized these fluorescent mutant melanophores in X. tropicalis tadpoles, providing a practical basis for avoiding fluorescent interference in experimental science and a new perspective on pigment cell development and evolution.

Optically stimulated luminescence (OSL) materials can convert trapped charge carriers into light under controllable light stimulation, thus holding great promise for diverse applications such as radiation dose detection and anti-counterfeiting. Nevertheless, previous OSL signals are located in the visible or near-infrared regions, overlapping seriously with the ambient light and thus hindering the application potential. Herein, we report a type of double perovskite structured phosphor, Cs2NaYF6:Pr3+, capable of emitting ultraviolet-C (UVC) OSL. Upon X-ray irradiation, Cs2NaYF6:Pr3+ can store the excitation energy in terms of trapped charge carriers. In addition, it exhibits strong and persistent UVC luminescence under continuous light stimulation over a wide wavelength range or heating. By investigating the wavelength-dependent stimulated luminescence phenomenon and trap-clearing capability, we elaborate on the influence of excitation wavelength on UVC OSL. Leveraging the luminescent properties of Cs2NaYF6:Pr3+, we further demonstrate its potential application in tracking and marking in bright environments when exposed to sunlight irradiation. This work clarifies the generation mechanism of UVC OSL and its dependence on stimulation wavelength, thereby providing insights for the exploration of more UVC OSL materials.

This work reports two lanthanide clusters, [Ln4(RPO3)2(RPO3H)(tBuCO2)7(tBuCO2H)3(H2O)3] (Ln=Eu, Tb; RPO3H2 denotes (9-methyl-9H-fluoren-9-yl)phosphonic acid). A comprehensive series of characterizations was performed for the Eu4 and Tb4 clusters, including X-ray crystallography, X-ray scintillation, and photoluminescence spectroscopy, to elucidate their structural features and physicochemical properties. Notably, these clusters exhibit exceptional X-ray scintillation performance, attributed to the characteristic luminescence of Ln3+ ions. This finding paves the way for the development of novel scintillator materials and enriches the family of lanthanide-bearing clusters with X-ray scintillating properties. Furthermore, photoluminescence modulation was achieved for the chemically mixed Eu/Tb analogues, c-EuxTb4-x (x=2.67, 2, 1.33), and physically mixed Eu4/Tb4 materials, p-yEu4:zTb4 (y:z=2:1, 1:1, 1:2), with varying the excitation wavelength. Notably, near-white-light emission is realized for p-Eu4:2Tb4 upon excitation at 365nm. Collectively, these tetranuclear lanthanide phosphonates exhibit excitation-wavelength and Eu3+:Tb3+ ratio dependent luminescence, indicating their potential as color-tunable luminescent materials and white-light-emitters.

A method utilizing quaternion principal component analysis (QPCA) for three-dimensional fluorescence spectral (3D FS) feature extraction is employed to identify frying oil in edible oil. Particle swarm optimization partial least squares support vector machine (PSO-LSSVR) is utilized for detecting frying oil concentration. The study includes rapeseed oil, soybean oil, peanut oil, blending oil, and corn oil samples. Adulteration involves adding frying oil to these edible oils at concentrations of 0%, 5%, 10%, 30%, 50%, 70%, and 100%. Firstly, the F7000 fluorescence spectrometer is employed to measure the 3D FS of the adulterated edible oil samples, resulting in the generation of contour maps and 3D FS projections. The excitation wavelengths utilized in these measurements are 360 nm, 380 nm, and 400 nm, while the emission wavelengths span from 220 nm to 900 nm. Secondly, leveraging the automatic peak-finding function of the spectrometer, a quaternion parallel representation model of the 3D FS data for frying oil in edible oil is established using the emission spectra data corresponding to the aforementioned excitation wavelengths. Subsequently, in conjunction with the K-nearest neighbor classification (KNN), three feature extraction methods—summation, modulus, and multiplication quaternion feature extraction—are compared to identify the optimal approach. Thirdly, the extracted features are input into KNN, particle swarm optimization support vector machine (PSO-SVM), and genetic algorithm support vector machine (GA-SVM) classifiers to ascertain the most effective discriminant model for adulterated edible oil. Ultimately, a quantitative model for adulterated edible oil is developed based on partial least squares regression, PSO-SVR and PSO-LSSVR. The results indicate that the classification accuracy of QPCA features combined with PSO-SVM achieved 100%. Furthermore, the PSO-LSSVR quantitative model exhibited the best performance.

BackgroundLive-cell fluorescence microscopy enables the study of dynamic cellular processes. However, fluorescence microscopy can damage cells and disrupt these dynamic processes through photobleaching and phototoxicity. Reducing light exposure mitigates the effects of photobleaching and phototoxicity but results in low signal-to-noise ratio (SNR) images. Deep learning provides a solution for restoring these low-SNR images. However, these deep learning methods require large, representative datasets for training, testing, and benchmarking, as well as substantial GPU memory, particularly for denoising large images.ResultsWe present a new fluorescence microscopy dataset designed to expand the range of imaging conditions and specimens currently available for evaluating denoising methods. The dataset contains 324 paired high/low-SNR images ranging from four to 282 megapixels across 12 sub-datasets that vary in specimen, objective used, staining type, excitation wavelength, and exposure time. The dataset also includes spinning disk confocal microscopy examples and extreme-noise cases. We evaluated three state-of-the-art deep learning denoising models on the dataset: a supervised transformer-based model, a supervised CNN model, and an unsupervised single image model. We also developed an image stitching method that enables large images to be processed in smaller crops and reconstructed.ConclusionsOur dataset provides a diverse benchmark for evaluating deep learning denoising methods, and our stitching method provides a solution to GPU memory constraints encountered when processing large images. Among the evaluated deep learning models, the supervised transformer-based model had the highest denoising performance but required the longest training time.

High-quality seed material is a critical factor in the efficient production of grain and its products. Producing high-quality products requires more plant protein, a source of which is chickpeas. Quality control, which can be accomplished using optical methods, is of great importance when storing grain and seeds. The purpose of the current study was to validate the selection of informative spectral parameters to develop a photoluminescence diagnostic method for chickpeas. There were studied the optical spectral luminescence properties of middle-maturing chickpeas ‘Pamyat’ harvested in 2024, 2019, and 2017. Optical measurements were performed using a diffraction spectrum fluorimeter ‘CM2203’. There have been obtained excitation (absorption) and luminescence spectra. Chickpea excitation was in the range of 250–550 nm, with maxima at 362 and 424 nm for all samples studied. The greatest difference in the integral absorption parameter was in the excitation range of 370–500 nm. There were obtained integral parameters of the luminescence spectra at excitation wavelengths of 362 and 424 nm. Integral photoluminescence fluxes depended on storage time and percentage of protein and oil in seed. The error in determining the fluxes did not exceed 4.5 %. The most informative excitation wavelength was selected based on the condition of the maximum photo signal level, minimum error in determining the flux, and the greatest flux increase for different values of protein and oil percentage. The optimal excitation wavelength was 424 nm. The photoluminescence emission detection range for this excitation wavelength was 480–650 nm. The results obtained could form the basis to develop a photoluminescence method for monitoring chickpea parameters during long-term storage.

Coiled-coil peptides incorporating cyclic β-amino acids, such as trans-(1S,2S)-2-aminocyclopentanecarboxylic acid (trans-ACPC), offer a versatile scaffold for engineering foldamers with tailored self-assembly and photophysical properties. Here, we investigate how solvent polarity and hydrogen-bonding capacity modulate two intrinsic features of such foldamers: autofluorescence and supramolecular organization. A series of trans-ACPC-modified and unmodified coiled-coil peptides were synthesized and characterized by circular dichroism (CD), steady-state and time-resolved fluorescence spectroscopy (SSFS and TRFS), transmission electron microscopy (TEM), and attenuated total reflectance─Fourier-transform infrared (ATR-FTIR) in water, ethanol, and acetonitrile. All peptides exhibited label-free fluorescence, with emission maxima and lifetimes varying systematically with the solvent environment and aggregate morphology. Insertion of a trans-ACPC residue rigidified the backbone, reduced solvent sensitivity, and promoted more homogeneous photophysical responses. TEM and distribution-free statistics show solvent-programmed morphologies, with water favoring extended fibrils, ethanol predominantly yielding globular or shorter twisted aggregates, and acetonitrile producing compact, less ordered clusters with intermediate cross sections (H2O < ACN < EtOH). ATR-FTIR spectra in the amide I/II region reveal solvent-dependent band positions consistent with reorganized hydrogen-bond networks and through-space interactions among backbone carbonyls, supporting the proposed carbonyl-lock contribution to emission. Across solvents, excitation and emission wavelengths follow the expected solvatochromic ordering (most red-shifted in water, blue-shifted in ethanol, and further in acetonitrile), whereas fluorescence lifetimes are broadly similar in water and acetonitrile and shortened in ethanol, indicating only a partial correlation between supramolecular order and decay kinetics. Thus, the external solvent programs intrinsic emissive states by reshaping backbone packing and hydrogen-bond topology rather than introducing new chromophores. These findings establish a structure-solvent-photophysics relationship for cyclic β-amino acid-containing coiled-coils and highlight their potential as intrinsically emissive nanomaterials and optical probes in environments where external labels are undesirable.

Combination cancer therapy, a treatment modality combining two or more therapeutic strategies, has attracted attention for treating various types of cancer. In this study, we produced near-infrared (NIR)-induced multi-shell upconversion nanoparticle (MUN)-based therapeutic nanocarriers co-loaded with chlorin e6 (Ce6) and indoximod (IND) (FMUN3-Ce6/IND) to combine tumor-targeted photodynamic therapy (PDT) with immunotherapy. Upconversion nanoparticles doped with rare-earth elements are synthesized into multi-shell structures to improve their upconversion luminescence efficiency. In particular, their emission intensity in the red region, which is the excitation wavelength of Ce6, increased by ∼519 times compared with the core nanoparticles, which enhanced the PDT effect. The MUN-based nanocarriers showed more than 18-fold better ROS generation than free Ce6 under 808nm NIR laser irradiation. FMUN3-Ce6/IND nanocarriers conjugated with a folic acid ligand showed particularly high phototoxicity to HeLa cells overexpressing folate receptors due to their active targeting effect. FMUN3-Ce6/IND nanocarriers increased the ratio of CD3+CD8+ to CD3+CD4+FoxP3+ T cells by approximately 5.4-fold compared to FMUN3-Ce6 without IND, indicating that inhibition of Trp metabolism by IND effectively promotes CD8+ T cell proliferation and suppresses Treg cells, thereby enhancing the antitumor immune response. Furthermore, the synergistic antitumor efficacy of FMUN3-Ce6/IND combining PDT and immunotherapy under in vivo conditions is demonstrated. These results suggest that multi-shell FMUN-based nanocarriers offer a promising platform for synergistic combination therapy, addressing the limitations of monotherapy with IDO inhibitors and overcoming the restricted tissue penetration and low ROS generation associated with conventional PDT.

Single component white-light emitters with cool-white emission are highly desirable, yet metal halide perovskites of this kind remain rare. Traditionally, white-light emission is achieved by combining blue and yellow phosphors, incurring efficiency losses. We present a zero-dimensional zirconium halide phosphor, (PPh4)2ZrCl6 (PPh4+: tetraphenylphosphonium cation), exhibiting intrinsic cool-white-light emission with Commission Internationale de l'Eclairage (CIE) coordinates of (0.33, 0.33) at 320 nm excitation with a correlated color temperature (CCT) of 5609 K, closely aligning with ideal white-light standards. The isolated [ZrCl6]2- octahedra induce a strong exciton binding energy of 358.7 meV, along with dual emission bands from singlet and triplet self-trapped excitons (STEs), which are tunable via the excitation wavelength. With increasing pressure up to 9 GPa, the emission band at 442 nm intensifies at the expense of 610 nm emission. Mechanical force shifts the emission from cool white to deep blue, shifting the CIE coordinates to (0.19, 0.18) for fully crushed crystals, due to a gradual reduction in the density of states near the Fermi level and the sharpening of band edges. Our findings establish (PPh4)2ZrCl6 single crystals as promising white-light phosphors with tunable properties, offering new insights into single-component emitters and stimuli-responsive photoluminescent materials.

Nitrogen and sulfur co-doped carbon quantum dots (N,S-CQDs) were synthesized via a green, one-step hydrothermal method using waste lemon peel as the carbon source and glutathione (GSH) as the N,S dopant in a dimethylformamide (DMF) medium. The reaction was conducted at 180 °C for 10 hours to achieve efficient synthesis. The resulting N,S-CQDs showed excellent water dispersibility, strong photostability, and bright fluorescence, with optimal excitation and emission wavelengths of 340 nm and 420 nm, respectively. High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared spectroscopy (FT-IR) confirmed their uniform morphology and successful incorporation of nitrogen and sulfur heteroatoms. Notably, the fluorescence of the N,S-CQDs could be rapidly and selectively quenched by Hg2+ within 10 minutes at room temperature, without requiring any additional surface modification of the CQDs or auxiliary reagents in the sensing procedure. Under optimized conditions, the sensor exhibited a linear fluorescence quenching response to Hg2+ over the concentration range of 17.6 nM to 20 µM (R2 = 0.9899), with a low detection limit of 17.6 nM. Mechanistic studies suggested that the quenching primarily resulted from the formation of nonfluorescent complexes between Hg2+ and functional groups on the CQD surface. The developed sensor was successfully applied to detect trace levels of Hg2+ in real lake water samples collected near textile manufacturing sites, demonstrating its potential as a sustainable, rapid, and cost-effective tool for practical environmental mercury monitoring.

Organic-inorganic metal halides (OIMHs) have emerged as highly promising novel multifunctional optoelectronic materials, owing to their easily adjustable properties from a variety of combinations of different components. But it is still difficult and rare to realize highly tunable multicolor luminescence within the same material. In this work, we successfully incorporated three adjustable emission centers in OIMHs to synthesize a novel OIMH (NEA)2MnBr4, with each emission center capable of emitting one of the primary colors-red, green, and blue. The green and red emissions originate from the tetrahedron and octahedron structures in the Mn-based frame, while the blue can be attributed to the contribution of organic components. Additionally, to achieve comparable emission intensity among the three primary colors, we enhanced the blue emission performance by optimizing the ratio of organic structure components and incorporating chirality in the OIMHs. The resulting high-quality films can be obtained by spin-coating method with a photoluminescence quantum yields of up to 96%. More interestingly, by the dual manipulation of excitation wavelength and temperature, the sample can be emitted at least seven distinct colors including a standard white luminescence at (0.33, 0.33), opening up promising prospects for multicolor luminescence applications such as high-end anti-counterfeiting technology, light-emitting diodes, X-ray imaging, latent fingerprints, humidity detection, and so on. Therefore, based on application scenarios and requirements, our research on this highly tunable luminescent OIMH material lays a solid foundation for further development of various functional properties of related materials.

Mott insulators are a unique class of materials whose insulating state originates from strong electron-electron correlations: the interactions localize charge carriers, and the resulting on-site Coulomb repulsion opens a charge gap, fundamentally different from conventional insulators, making these systems an exceptional platform for exploring exotic physical phenomena. Significantly, the interplay between strong correlations and charge transfer not only stabilizes the antiferromagnetic ground state but also endows the material with enriched properties, particularly in optics. Herein, we demonstrate a 2D antiferromagnetic charge-transfer Mott insulator, Vanadium Oxychloride (VOCl), which shows giant third-harmonic generation (THG) anisotropy (ρTHG = Ix/Iy, where Ix and Iy represent the THG intensities corresponding to the excitation polarization parallel to crystal’s x- and y-axes), with ρTHG reaching up to 187 at 1280 nm excitation wavelength. Notably, it is the highest THG anisotropic ratio within the van der Waals materials family. The nonlinear anisotropy is further modulated across a broadband infrared (IR) excitation wavelength range from 2028 to 1280 nm, during which ρTHG rises from 2.6 to 187, corresponding to a 72-fold enhancement relative to its value at 2028 nm. Additionally, VOCl demonstrates layer-independent third-order susceptibilities (χ(3) ~ 10-19 m2/V2) and band structures attributed to its extremely weak interlayer electronic coupling. Moreover, the colossal THG anisotropic ratio in 2D VOCl can be ascribed to the synergistic effect of the correlated charge-transfer Mott insulator behavior and intrinsic C3 symmetry breaking, as supported by theoretical calculations. The colossal nonlinear optical anisotropy in 2D VOCl positions it as an excellent candidate for nanophotonic and optoelectronic applications, enabling next-generation nanodevices based on 2D correlated Mott insulators.

The near-infrared dye indocyanine green (ICG) is widely used for biomedical imaging, yet its photophysical behavior remains incompletely understood. We have investigated how viscosity affects ICG fluorescence in methanol:glycerol mixtures. Increasing the glycerol content raised the viscosity and increased the fluorescence quantum yield (FQY) and lifetime in a way that could not be explained by changes in the solvent's polarity. ICG also exhibited an unusual violation of the Kasha-Vavilov rule that FQYs are generally independent of the excitation wavelength. Calculations using density functional theory revealed that the changes in FQY reflect formation of a nonfluorescent twisted conformation. Twisting around one of the bonds in the central polymethine chain has a calculated energy barrier of about 0.3 eV that can be surmounted at the expense of excess vibrational energy when the molecule is excited on the blue side of the absorption band but not with excitation at the absorption maximum.

The effect of modifying substituents in the rotor group of five second generation molecular motors is estimated by theoretical calculations. The rotational speed is estimated by calculating the rate limiting step, the thermal helix inversion, and the competing backward transition using harmonic transition state theory with energy and atomic forces obtained from density functional theory. First, a methyl group at the stereogenic center is replaced with a tert-butyl (tBu) group, and the rotational speed is found to increase due to reduced lifetime of the metastable state. For two of the rotors, comparison can be made with experimental measurements, and the calculated half-life is in close agreement. Second, the effect of substituting the nine hydrogen atoms in the tBu group with fluorine atoms is studied, and this is found to increase the rotational rate further without significantly altering the molecular structure. The excitation wavelength of both the stable and metastable states is calculated, and the separation of the absorption peaks is found to increase by the tBu substitution and even more so by the fluorinated tBu substitution, up to 40 nm. These findings can help to develop a strategy for designing molecular motors with a rotational speed that best fits a given application.