Search Results (223)

Graphene quantum dots (GQDs) obtained by microwave-induced pyrolysis of glutamic acid and triethylenetetramine (trien) are fairly stable, emissive, water-soluble, and positively charged nano-systems able to interact with negatively charged meso-tetrakis(4-sulfonatophenyl) porphyrin (TPPS₄). The stoichiometric control during the preparation affords a supramolecular adduct, GQDs@TPPS₄, that exhibits a double fluorescence emission from both the GQDs and the TPPS₄ fluorophores. These supramolecular aggregates have an overall negative charge that is responsible for the condensation of cations in the nearby aqueous layer, and a three-fold acceleration of the metalation rates of Cu²⁺ ions has been observed with respect to the parent porphyrin. Addition of various metal ions leads to some changes in the UV/Vis spectra and has a different impact on the fluorescence emission of GQDs and TPPS₄. The quenching efficiency of the TPPS₄ emission follows the order Cu²⁺ > Hg²⁺ > Cd²⁺ > Pb²⁺ ~ Zn²⁺ ~ Co²⁺ ~ Ni²⁺ > Mn²⁺ ~ Cr³⁺ >> Mg²⁺ ~ Ca²⁺ ~ Ba²⁺, and it has been related to literature data and to the sitting-atop mechanism that large transition metal ions (e.g., Hg²⁺ and Cd²⁺) exhibit in their interaction with the macrocyclic nitrogen atoms of the porphyrin, inducing distortion and accelerating the insertion of smaller metal ions, such as Zn²⁺. For the most relevant metal ions, emission quenching of the porphyrin evidences a linear behavior in the micromolar range, with the emission of the GQDs being moderately affected through a filter effect. Deliberate pollution of the samples with Zn²⁺ reveals the ability of the GQDs@TPPS₄ adduct to detect sensitively Cu²⁺, Hg^2+, and Cd²⁺ ions. Full article

In ecotoxicological risk assessment, current methods for measuring the transfer and bioavailability of organic pollutants like polycyclic aromatic hydrocarbons (PAHs) in bioindicators are often destructive and environmentally unfriendly. These limitations are especially problematic when only small amounts of biological material are available. Here, we present a novel, high-throughput method combining laser-induced UV fluorescence spectroscopy (UV-LIF) and solid-phase spectroscopy (SPS) for rapid, in situ quantification of PAHs in land snails—a key bioindicator species. Using dual excitation wavelengths (266 nm and 355 nm), our method reliably detected pyrene and fluoranthene in snails exposed to varying concentrations, demonstrating clear dose-responses and inter-individual differences in bioaccumulation. The analysis time per sample was under four minutes. This approach allows simultaneous measurement of internal contaminant levels and health biomarkers in individual organisms and aligns with green chemistry principles. These findings establish a new, scalable tool for routine assessment of PAH transfer and bioavailability in diverse ecosystems. Full article

In this study, we describe the preparation of carbon dots (CDs) from natural charcoal by laser ablation in a liquid. A continuum wave (CW) laser diode operating at a wavelength of 450 nm, hitting a solid carbon target placed into a biocompatible liquid, constituted of a phosphate-buffered saline (PBS) solution and distilled water, was used for the generation of the CDs suspension. Exploring the practical applications of carbon dots, it was observed that the luminescence of the produced CDs can be used as bioimaging in living organisms, environmental monitoring, chemical analysis, targeted drug delivery, disease diagnosis, therapy, and others. The CDs’ luminescence can be induced by UV irradiation and, as demonstrated in this study, by energetic MeV proton beams. The fluorescence was revealed mainly at 480 nm when UV illuminated the CDs, and also in the region at 514–642 nm when the CDs were irradiated by energetic proton ions. Atomic force microscopy (AFM) of the CD films revealed their spherical shape with a size of about 10 nm. The significance of the manuscript lies in the use of CDs produced by laser ablation exhibiting luminescence under irradiation of an energetic proton beam. Full article

In this work, methyl viologen (MV) was adsorbed into the nanopores of Si/Al H-β-zeolite via cation exchange. The resulting MV@β-zeolite possessed absorption/fluorescence dual-mode and photo/chemical synergistic stimuli-responsive chromism. Owing to the acidic surrounding provided by β-zeolite, the chromism of MV required the synergistic stimuli of UV irradiation and a chemical reductant (such as Na₂SO₃). UV irradiation induced single electron transfer from the chemical reductant to MV@β-zeolite, leading to enhanced absorption at 610 nm together with a daylight color change from pale yellow to blue. Meanwhile, the nanopores of β-zeolite inhibited aggregation-caused quenching of MV, enabling MV to emit cyan fluorescence at 500 nm. After the single electron transfer of the chemical reductant under UV irradiation, the cyan fluorescence of MV@β-zeolite was quenched. Additionally, MV@β-zeolite exhibited a short stimulus response time (250 s) and good color change reversibility. These findings in this work provide valuable insights into the design of multi-mode and synergistic stimuli-responsive viologen-based chromic materials, particularly for applications in secure high-throughput information storage, high-level anti-counterfeiting and multi-target multi-mode sensing. Full article

The present study compared the free and encapsulated photosensitizer hypocrellin B (HB) in terms of photophysical-chemical properties, cellular uptake, subcellular distribution, and phototoxicity. The hydrophobic HB was encapsulated into liposomes (HB@Lipo) or poly (lactic-co-glycolic acid) nanoparticles (HB@PLGA). Encapsulation into nanocarriers exerted no obvious influence on the photophysical-chemical properties of HB, including UV-visible absorbance, fluorescence spectra, singlet oxygen (¹O₂) production capacity, and photostability. Free and encapsulated HB revealed some disparities in cellular uptake and subcellular localization patterns. In 2D-cultured B16 cells and tumor spheroids, free HB exhibited the fastest cellular uptake, while HB@PLGA had the lowest, as evidenced. Subcellular localization analysis first revealed a significant colocalization of free HB, HB@Lipo, and HB@PLGA within lipid droplets, with minimal colocalization in mitochondria and the endoplasmic reticulum. Unlike free HB and HB@Lipo, HB@PLGA exhibited strong lysosomal colocalization, indicating a unique intracellular trafficking pathway for PLGA-encapsulated HB. Upon laser irradiation, both free and encapsulated HB induced pronounced phototoxicity with substantial ROS production, confirming the robust PDT effect of HB. The photodynamic killing effect correlated with the intracellular HB content. These findings highlighted the impact of nanoformulation on HB’s cellular behavior and therapeutic performance. Full article

Photochromic materials have attracted widespread attention due to their potential applications in optical information storage, optoelectronic devices, and fluorescence probes. As a typical photochromic system, diarylethene derivatives are considered one of the most promising photochromic materials due to their outstanding photostability and significant bistable properties. Based on an aggregation-induced emission (AIE) mechanism, this study employed a molecular structural engineering strategy to design and synthesize a series of diarylethene derivatives containing ethyl benzoate substituents. A systematic investigation of the structure–activity relationship between their photochromic behavior and AIE characteristics revealed a dual-state light response mechanism in the solid and solution states. This study demonstrates that the target compounds exhibited significant photochromic responses under UV–visible light irradiation, with enhanced emission in the solid state compared to the solution state, confirming the remarkable enhancement effect of AIE on aggregation. Structural characterization techniques such as nuclear magnetic resonance spectroscopy (NMR) and high-resolution mass spectrometry (H RMS) were employed to elucidate the correlation between molecular conformation and photophysical properties. Furthermore, these materials demonstrated potential for multi-level anti-counterfeiting, high-density optical storage, and bioimaging applications, providing experimental foundations for the development of novel multifunctional photochromic materials. Full article

Vanadium-bearing beryl is a vanadium-bearing variety of green beryl (distinct from emerald) that exhibits an “electro-optical” green (blue-green) color, which has led to its commercial popularity. However, the underlying coloration mechanism remains unclear. The present study adopted standard gemological tests and non-destructive spectroscopic tests, such as X-ray fluorescence, UV-visible-near infrared (UV-Vis-NIR), infrared and Raman spectroscopy, to analyze the vanadium-bearing beryl from Nigeria. The results of these tests indicated the presence of Fe as the predominant chromogenic element of vanadium-bearing beryl, followed by V, at a level exceeding that of Cr. Furthermore, the samples displayed lower levels of alkali and magnesium when compared to other beryls, accompanied by lower refractive indices and specific gravities. Spectroscopic analysis indicates that the structural channels are dominated by type I H₂O, with CO₂, HDO, and D₂O molecules also present. The inclusions observed in vanadium-bearing beryl bear a resemblance to those found in typical aquamarines, which are raindrop-shaped inclusions, and to those found in emeralds of various origins, which are irregular, jagged, gas–liquid two-phase/three-phase inclusions. The broad UV-Vis-NIR absorption bands at 427 and 610 nm are characteristic of V³⁺ (and a minor amount of Cr³⁺). Charge transfer between Fe²⁺ and Fe³⁺ may also contribute to the 610 nm band, which is superimposed on the absorption bands of V³⁺ and Cr³⁺. These factors primarily contribute to the blue-green coloration of beryl. The absorption induced by V³⁺ in the visible violet-blue region exhibits stronger intensity and a greater tendency towards the blue region compared to Cr³⁺. Consequently, the resultant vanadium-bearing beryl acquires the yellow-green hue (induced by V) overlaid with the light blue (induced by charge transfer between Fe²⁺-Fe³⁺ pairs), resulting in the so-called “electro-optical” green (blue-green) beryl. Full article

Hemocyanins are oxygen-transporting proteins found in crustaceans and other arthropods, playing key roles in immune defense and metabolic regulation. Due to their stability and bioactive properties, Hcs have gained increasing interest in biotechnological and biomedical applications. However, detailed biophysical characterization is crucial to understanding their functional potential. In this study, the hemocyanin was extracted and purified from Macrobrachium acanthurus (HcMac) using ultracentrifugation and size-exclusion chromatography. The molecular mass of HcMac was determined by SDS-PAGE electrophoresis, MALDI-TOF mass spectrometry, and analytical ultracentrifugation. Spectroscopic analyses, including UV-Vis absorption, fluorescence emission, and light scattering intensity, were used to assess the structural stability of the compound under various pH conditions. HcMac was identified as a hexameric protein (~450 kDa) composed of monomeric subunits of 75 and 76 kDa. The protein maintained its oligomeric stability and oxygen-binding affinity in the pH range of 5.0–7.4. However, extreme pH conditions (below 4.4 and above 7.5) induced structural alterations, leading to dissociation and conformational changes, as evidenced by fluorescence emission and UV-Vis spectra. The isoelectric point was determined to be between pH 4.3 and 5.3, consistent with other crustacean HCs. These findings reinforce the structural robustness of HcMac and suggest its potential for biotechnological applications. The high stability of HcMac under physiological pH conditions indicates its suitability for biomedical research, including immunomodulatory and antimicrobial applications. Future studies integrating bioinformatics, proteomics, and immunological assays will be essential to explore the therapeutic potential of HcMac. Full article

Several strategies, including UV detection with a diode array detector (DAD), laser-induced fluorescence (LIF), derivatization reactions, the use of micelles in the separation buffer, as well as online preconcentration techniques based on pressure-assisted electrokinetic injection (PAEKI), and offline preconcentration using solid-phase extraction (SPE) columns containing quaternary amine groups with a chloride counterion, were investigated for the simultaneous separation and signal amplification of free thyroid hormones (THs) in biological samples. Moreover, a sensitive method for the quantification of THs in selected biological samples using micellar electrokinetic capillary chromatography with LIF detection (MEKC-LIF) was developed. The THs present in biological samples (L-tyrosine, T2, T3, rT3, T4, and DIT) were successfully separated in less than 10 min. The analytes were separated following a derivatization procedure with fluorescein isothiocyanate isomer I (FITC). A background electrolyte (BGE) composed of 20 mM sodium tetraborate (Na₂B₄O₇) and 20 mM sodium dodecyl sulphate (SDS) was employed. Key validation parameters such as linearity, precision, limits of detection (LOD), and limits of quantification (LOQ) were determined. The use of PAEKI for the electrophoretic determination of free THs demonstrates significant potential for monitoring these hormones in real urine samples due to its high sensitivity and efficiency. Full article

In this study, we report a green, one-step synthesis of fluorescent carbon quantum dots (PET-FCQDs) derived from polyethylene terephthalate (PET) waste using an environmentally friendly pyrolytic method. The PET-FCQDs were systematically characterized using techniques such as UV-Vis spectroscopy, fluorescence spectroscopy, ATR-FTIR, TGA, and fluorescence microscope, confirming their nanoscale size (2–50 nm), rich functional groups and thermal stability. Thermal stability and dynamics evaluated by the Coats–Redfern method showed endothermic reactions with an activation energy of 88.84–125.05 kJ/mol. Density functional theory studies showed a binding energy, highest occupied molecular orbital, lowest unoccupied molecular orbital, and energy gap of −675.39, −5.23, −5.07, and 0.17 eV, respectively. The as-synthesized PET-FCQDs demonstrated excellent optical properties with quantum yield ($\Phi$) of 49.6% and were applied as a dual-mode fluorescent sensing probe for the detection of Pd²⁺, ciprofloxacin (CIP), and fluoxetine (FLX) in aqueous systems via fluorescence quenching and enhancement mechanisms. For Pd²⁺, the fluorescence emission intensity at 470 nm was quenched proportionally to the increasing concentration, while CIP and FLX induced fluorescence enhancement. The Stern–Volmer analysis confirmed strong interaction between the analytes and PET-FCQDs, distinguishing dynamic quenching for Pd²⁺ and static interactions for CIP and FLX. The method exhibited linear detection ranges of 1–10 mg/L for Pd²⁺, 50–150 µg/L for CIP, and 100–400 ng/L for FLX, with corresponding limits of detection (LOD) of 1.26 mg/L, 3.3 µg/L, and 134 ng/L, respectively. Recovery studies in spiked tap water and river water samples demonstrated the practical applicability of PET-FCQDs, although matrix effects were observed, particularly for FLX. This work not only highlights a sustainable route for PET waste upcycling but also demonstrates the potential of PET-FCQDs as cost-effective, sensitive, and versatile fluorescent probes for environmental monitoring of heavy metal ions and pharmaceutical pollutants. Further optimization of the sensing platform could enhance its selectivity and performance in real-world applications. Full article

This study investigates the synthesis, characterization, and cytotoxicity of dinuclear palladium(II) complexes with glycine (Pd1), alanine (Pd2), and methionine (Pd3) as ligands. UV-Vis and fluorescence spectroscopy were used to investigate the complexes’ interactions with calf thymus DNA (CT-DNA) and bovine serum albumin. The obtained measurements demonstrate that Pd1 and Pd2 have stronger binding affinities for CT-DNA compared to Pd3, with Pd3 exhibiting the most significant cytotoxicity against the MDA-MB-231 cancer cell line. The binding behavior was quantified by calculating intrinsic binding constants (K_b) and Stern–Volmer constants (K_sv), showing that Pd1 and Pd2 interact more effectively with DNA, possibly due to less steric hindrance in their chelation. Cytotoxic activity was evaluated using an MTT assay, and the results confirm that Pd3, with methionine as the ligand, exhibited superior antitumor effects, inducing apoptosis through caspase-3 activation. The complexes also showed a strong affinity for BSA, indicating their potential for biological interaction. These discoveries shed light on the processes of palladium(II) complexes in biological systems, highlighting their DNA and protein-binding capabilities, as well as their anticancer potential. Further research is required to explore their pharmacokinetics and possible clinical applications. Full article

Lignin, a significant industrial byproduct from paper manufacturing processes, exhibits ultraviolet (UV) radiation absorption properties. Cellulose nanofibers (CNFs) demonstrate universal ligand characteristics and represent an innovative approach for converting industrial waste into value-added products. Given their potential applications in cosmetic formulations, their efficacy and safety parameters, such as their photoprotection mechanisms and phototoxicity, need to be investigated. Therefore, two kraft lignin fractions, LE and R1, along with a kraft-bleached pulp CNF, were evaluated for their phototoxicity and photoprotection mechanisms, both using the HaCaT cell line (immortalized human keratinocytes) as the in vitro model. Phototoxicity assessment involved exposing cells to UVA radiation (4 J/cm²), with the subsequent comparison of cell viability between irradiated and non-irradiated samples. ROS quantification was performed using a 2′,7′-dichlorofluorescein diacetate (DCF-DA) probe, with fluorescence intensity measurements, and was then used to evaluate the photoprotection effect. The results demonstrated that both LE and R1 exhibited concentration-dependent increases in phototoxicity, whereas CNF showed no phototoxic effects under the conditions tested. For photoprotection, LE, R1, and CNF reduced UV-induced ROS production, a result which could be associated with antioxidant properties in the case of the lignin fractions. These findings suggest that both lignin fractions and CNF hold promise for use in renewable and sustainable cosmetic formulations. Full article

Introduction: Basal cell carcinoma (BCC) is the most frequently diagnosed skin cancer globally. Despite the well-established dermoscopic features of BCC, overlapping characteristics with other benign and malignant skin conditions cause challenges in differential diagnosis. Part III of this review highlights the role of dermoscopy in differential diagnosis, treatment planning, therapy monitoring and the integration of novel technologies including ultraviolet-induced fluorescence dermoscopy (UVFD) and optical super-high magnification dermoscopy (OSHMD). Methods: A search of the PubMed database was conducted for studies reporting on advances in the dermoscopic assessment of BCC, including differential diagnosis, treatment, monitoring and novel diagnostic technologies. Results: Even entities with well-defined dermoscopic features distinguishing them from BCC can sometimes mimic BCC. Additionally, rare lesions such as neurothekeoma, reticulohistiocytoma, solitary circumscribed neuroma, dermal leiomyosarcoma and various adnexal tumors often remain dermoscopically indistinguishable from BCC, which underscores the importance of histopathology as the diagnostic gold standard. Dermoscopy aids in delineating the tumor margins, optimizing Mohs micrographic surgery (MMS) and traditional excision. It may also help to monitor therapeutic effects by detecting the disappearance of BCC patterns, the presence of residual tumor or recurrences. Dermoscopy may aid in the prediction of therapeutic responses to imiquimod, photodynamic therapy or vismodegib. UVFD and OSHMD appear to be valuable complementary diagnostic techniques for detecting BCC. UVFD seems to be particularly valuable for the detection of small tumors (<5 mm), facial lesions and nodular or non-pigmented BCC subtypes, while OSHMD is useful for the assessment of superficial and non-pigmented BCCs. Three-dimensional total-body photography enhances diagnostic precision but, so far, only when used in combination with traditional dermoscopy. Conclusions: Dermoscopy is valuable for margin delineation, therapy monitoring and differential diagnosis but can be inconclusive, which highlights the role of histopathology as the gold standard. Modifications in dermoscopy technique may further enhance its accuracy. Full article

This study investigates the liquid crystalline behavior, photophysical properties, and metal ion sensing capabilities of a pyrene-based imine dimer (DPyH9). The compound exhibits monotropic nematic mesophase behavior, with a glass transition at 43 °C, as confirmed by polarized light microscopy (PLM) and differential scanning calorimetry (DSC). Its photophysical properties, including UV-vis absorption, solvatochromic fluorescence, and acidochromism, observed through spectral shifts upon HCl addition, were systematically analyzed. Notably, DPyH9 displayed selective metal ion sensing capabilities towards Sn²⁺ and Cu²⁺ with binding constants of 4.51 × 10⁶ M⁻¹ and 4.03 × 10⁷ M⁻¹ and detection limits of 1.61 × 10⁻⁵ M (Sn²⁺) and 4.73 × 10⁻⁵ M (Cu²⁺). Fluorescence titrations revealed distinct responses: Sn²⁺ induced an initial quenching and an enhancement at higher concentrations, while Cu²⁺ caused significant fluorescence quenching. These results therefore highlight DPyH9 as a potential candidate for sensing applications and optoelectronic devices. Full article

Photoaging is common and represents one of the primary pathways for hair damage in daily life. Hydrolyzed keratin, which is usually derived from wool and consists of a series of polypeptide molecules, has been investigated as a UV damage prevention ingredient for hair care. Scanning Electron Microscopy (SEM) and fluorescent penetration experiments verified that hydrolyzed keratin can deposit on the hair cuticles to form a film and partly penetrate into the hair cortex. This film played as a UV reducer and helped hair resist surface damage and maintain a sleek and healthy morphology after UV radiation. Surprisingly, it was found that hydrolyzed keratin treatment combined with subsequent UV radiation could significantly improve the tensile properties of hair. For hydrolyzed-keratin-treated hair, tensile strength was maintained after UV radiation, while, as a comparison, it decreased by 14.32% for untreated hair. This phenomenon is explained by a UV-induced degradation–penetration mechanism. During UV radiation, an increase in free amino acid content and conductivity was observed for the hydrolyzed keratin solution, demonstrating photodegradation into smaller peptides and amino acids. The degradation of hydrolyzed keratin allowed it to more easily enter the interior of the hair cortex, thereby enhancing its tensile properties by enhancing the chemical bonds. Full article