Search Results (2,868)

Pearl color serves as the paramount criterion for quality assessment and commercial valuation in the global pearl industry. Freshwater nucleated pearls, which constitute 95% of global production, exhibit striking chromatic diversity. This study deciphers the chromogenic mechanisms of freshwater nucleated cultured pearls in Hyriopsis cumingii from Zhuji, China, through integrated spectroscopic (UV-vis-NIR and Raman), colorimetric (CIELAB), and trace-element (LA-ICP-MS) analyses. We identify polyene compounds as the primary organic chromophores, with C=C bond counts determining core hue: purple (12 C=C bonds), pink (11 C=C bonds), and white/orange (10 C=C bonds). Color expression is further modulated by nacre microstructure; densely aligned aragonite tablets enhance optical interference in purple pearls, whereas irregular tablet arrangements in pink and orange pearls promote diffuse scattering. Crucially, trace elements (Mn, Fe, Cu, Zn) contribute synergistically via metalloporphyrin formation (e.g., Mn-porphyrin in purple variants) and aragonite lattice substitutions. These findings reveal that pearl coloration arises from the interplay of biological factors (organic matrix), physical structure (nacre architecture), and chemical composition (trace elements), providing insights for quality enhancement and sustainable aquaculture practices. Full article

Miscanthus × giganteus particles possess excellent advantages in biodegradability and sustainability. However, their susceptibility to ultraviolet (UV) degradation limits wider outdoor applications. In the present work, electron beam (e-beam) radiation-induced grafting was used for the first time to attempt covalent grafting of UV absorbers onto miscanthus particles to address a major challenge in natural fiber stabilization. Two UV absorbers, 2-hydroxy-4-(methacryloyloxy) benzophenone (HMB) and 2-(4-benzoyl-3-hydroxyphenoxy) ethyl acrylate (BHEA), were explored using both pre-irradiation and simultaneous approaches. Pre-irradiation grafting did not achieve useful covalent fixation of HMB or BHEA, due in part to the premature decay of radicals at elevated temperatures and with solvent use, and the lignin-based quenching of radicals. Solvent-free mutual irradiation grafting failed due to immobility of the UV absorbers, while grafting of HMB in solvent failed due to radical-scavenging behavior. Grafting of BHEA was successfully achieved under solvent-based simultaneous irradiation, reaching up to 38 wt % DG in a butanone/2.5% H₂SO₄ system. This condition led to the improved UV stability of miscanthus particles, in which color change was reduced significantly after 1000 h of accelerated weathering; this was mainly linked to a beneficial pre-darkening effect which was induced by the presence of the acid. This work proposes a route of grafting strategy that aims to improve the photostability of miscanthus particles, paving the way for durable bio-based materials in outdoor composite applications. Full article

Pneumonia caused by Pneumocystis jirovecii poses a serious threat, particularly to immunocompromised patients such as those with HIV/AIDS, transplant recipients, or individuals undergoing chemotherapy. Its diagnosis is challenging because current methods, such as microscopy and certain molecular tests, have limitations in sensitivity and specificity, and require specialized equipment, which delays treatment initiation. In this context, CRISPR-Cas12-based methods offer a promising alternative: they are rapid, highly specific, sensitive, and low-cost, enabling more timely and accessible detection, even in resource-limited settings. We developed a simple and rapid detection platform based on the CRISPR-Cas12 coupled with lateral flow strips. A guide RNA was designed against DHPS, β-tubulin, and mtLSU rRNA genes. The guide corresponding to β-tubulin showed high sensitivity in the detection of P. jirovecii to produce a detectable fluorescence signal within the first 20–30 min. In addition, it demonstrated high specificity for P. jirovecii when DNA from other microorganisms was used. When coupled with lateral flow strips, high sensitivity and specificity were also observed for detecting positive samples, without the need for genetic amplification. CRISPR-Cas12 successfully detected P. jirovecii infection in an initial diagnostic application, demonstrating the potential of this method for integration into public health diagnostic systems, particularly in field, due to its adaptability, speed, and ease of use. Full article

Copper ions (Cu²⁺), indispensable in physiological processes yet toxic at elevated concentrations, require sensitive on-site monitoring. Here, a portable fluorescent sensing film (Y-CDs@BCM) was fabricated by anchoring yellow-emitting carbon dots (Y-CDs) into bacterial cellulose films, which enables rapid and sensitive detection of Cu²⁺ in complex real-world samples. The yellow fluorescent carbon dots (Y-CDs) were synthesized with the aid of o-phenylenediamine and 1-octyl-3-methylimidazolium tetrafluoroborate as precursors, exhibiting excellent fluorescence stability. The fluorescence of Y-CDs was selectively quenched by Cu²⁺ via the inner filter effect (IFE), allowing quantitative analysis with superior sensitivity compared to existing methods. By adding bacterial cellulose (BC) as a solid support, aggregation-induced fluorescence quenching was effectively reduced, and sensor robustness and portability were improved. Through smartphone-based colorimetric analysis, the Y-CDs@BCM sensor enabled rapid, visual interpretation of Cu²⁺ detection (within 1 min). Furthermore, cell viability and in vivo assays confirmed the biocompatibility of Y-CDs, indicating their suitability for biological imaging. This work presents an environmentally friendly, reliable, and practical method for on-site Cu²⁺ monitoring, emphasizing its broad application potential in food safety control and environmental analysis. Full article

Bacterial diseases of Pleurotus pulmonarius, caused by diverse pathogens and associated with a range of symptoms, reduce its commercial value and lead to substantial economic losses. While most research has focused on Pseudomonas tolaasii and its non-volatile toxin tolaasin, little is known about other bacterial pathogens and their volatile metabolites. In this study, two bacterial pathogens were isolated from symptomatic P. pulmonarius fruiting bodies in Guangxi, China, and identified as Ewingella americana and Cedecea neteri. Using headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS), we identified 16 volatile organic compounds (VOCs) produced by these two species, seven of which exhibited toxicity-inducing sunken lesions, discoloration, and inhibition of mycelial growth. Symptom severity was quantified by colorimetric analysis. Among the toxic VOCs, 2,4-di-tert-butylphenol was the most potent, inducing sunken lesions and slight discoloration at concentrations as low as 0.5 mg/mL, and causing significant inhibition of mycelial growth at 5 μg/L. The remaining VOCs also caused varying degrees of sunken lesions, yellowing or browning, and suppression of mycelial growth. This study is the first to demonstrate the pathogenic potential of VOCs produced by bacterial pathogens in P. pulmonarius, underscoring their role as important virulence factors and providing a foundation for further investigation into their mechanisms and control strategies. Full article

LED strips are increasingly used as lighting sources in public and private spaces. However, traditional photometric methods, such as integrating spheres, are unsuitable for measuring their light parameters, often resulting in significant errors and requiring expensive instrumentation or calibration. These errors are typically caused by non-uniform illumination of the internal surface or improper internal geometry, especially when measuring LED sources. This article presents the development of a low-cost integrating device specifically designed to measure LED strips’ light parameters. The device is a compact cube with a volume of less than 1.0 m³. It was tested against alternative methods using an integrating sphere and a goniophotometer in a professional photometric laboratory. The verification results confirmed its effectiveness. The device showed the maximum relative error of luminous flux measurement to be around 5% compared with the accurate, expensive goniophotometric method. For colorimetric measurements, the maximum Correlated Color Temperature (CCT) absolute error was about 35 K for an LED strip with a CCT of 4000 K, indicating a difference imperceptible to the human eye. These results demonstrate the device’s proper relevance in the research and development of LED strip-based lighting equipment to improve lighting equipment quality and control processes. The device is easy to replicate, significantly reducing production and transportation costs, making it an excellent solution for companies and research units seeking a cost-effective method for LED strip measurements. Additionally, the device can measure other light sources or luminaires with reasonably small sizes emitting light in only one hemisphere. The device is the basis of a patent application. Full article

Nicotinamide adenine-dinucleotide (NAD⁺) supplementation is a promising strategy to delay cellular aging in different areas, including cosmetic dermatology. However, low bioavailability and stability of NAD⁺ formulations are the main factors limiting its effectiveness as an anti-aging treatment. In light of the above, a liposomal formulation of NAD⁺ (LF-NAD⁺) was tested in this study and compared to NAD⁺ alone in primary human aortic endothelial cells (HAECs) and primary human epidermal keratinocytes (HEKas). Intracellular NAD⁺ was measured using a colorimetric assay. Cell survival was derived from lactate dehydrogenase release in supernatants. Cell senescence was measured by senescence-associated β-galactosidase staining. Molecular mechanisms underlying the reported effects were analyzed by Western blot. Skin penetration of NAD⁺ was measured ex vivo in skin explants, using infrared spectroscopy. Compared to control NAD⁺ alone, the LF-NAD⁺ formulation increased the intracellular NAD⁺ content and cell survival in HAECs, but not in HEKas. Instead, a significant reduction in the number of senescent cells was observed in both HAECs and HEKas. LF-NAD⁺ treatment was associated with a reduced expression of p16 in both HAECs and HEKas, and to a significant reduction in p21 in HEKas alone. Finally, LF-NAD⁺ increases the skin penetration of the active substance NAD⁺ by 30% compared to the application of NAD⁺ alone. LF-NAD⁺, enhances the anti-aging effects of NAD⁺ on vascular and skin cells. Such in vitro findings might indicate a potential anti-aging role in the microcirculation and in the epidermidis. Full article

Nitrosamines, including N-nitroso diethylamine (NDEA) have emerged as pharmaceutical impurities and carcinogenic environmental contaminants of grave public health safety concerns. This study reports on the preparation and first use of cysteine–gold nanoparticles (CysAuNPs) for colorimetric detection of NDEA in human serum albumin (HSA) under physiological conditions. Molecular docking (MD) and molecular dynamic simulation (MDS) were performed to probe the interaction between NDEA and serum albumin. UV–visible absorption and fluorescence spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM) imaging were used to characterize the synthesized CysAuNPs. These CysAuNPs show a UV–visible absorbance wavelength maxima (λ_max) at 377 nm and emission λ_max at 623 nm. Results from DLS measurement revealed the CysAuNPs’ uniform size distribution and high polydispersity index of 0.8. Microscopic imaging using TEM showed that CysAuNPs have spherical to nanoplate-like morphology. The addition of NDEA to HSA in the presence of CysAuNPs resulted in a remarkable increase in the absorbance of human serum albumin. The interaction of NDEA–CysAuNPs–HSA is plausibly facilitated by hydrogen bonding, sulfur linkages, or by Cys–NDEA-induced electrostatic and van der Waal interactions. These are due to the disruption of the disulfide bond linkage in Cys–Cys upon the addition of NDEA, causing the unfolding of the serum albumin and the dispersion of CysAuNPs. The combined use of molecular dynamic simulation and colorimetric experiment provided complementary data that allows robust analysis of NDEA in serum samples. In addition, the low cost of the UV–visible spectrophotometer and the easy preparation and optical sensitivity of CysAuNPs sensors are desirable, allowing the low detection limit of the CysAuNPs sensors, which are capable of detecting as little as 0.35 µM NDEA in serum albumin samples, making the protocol an attractive sensor for rapid detection of nitrosamines in biological samples. Full article

Antioxidants, such as flavonoids, are influential secondary metabolites that play a significant role in regulating human health. Açaí, known for its potent antioxidant properties, has gained popularity in the nutritional field. However, there is a need for accurate methods to quantify its antioxidant capacity. Therefore, the goal of this investigation was to determine the total antioxidant capacity of frozen açaí pulp by applying the concept of the electrochemical quantitative index (EQI) using the cyclic voltammetry technique. The electrochemical response of ethanolic extracts obtained by a nonconventional ultrasound bath was investigated in the anodic region. The results clearly showed redox behavior at +0.37 V and +0.27 V (vs. Ag/AgCl) for the anodic and cathodic peaks, respectively, when evaluated by cyclic voltammetry at a glassy carbon (GC) electrode. By investigating a constant ethanolic extract concentration (0.2%) and analyzing the scan rate and supporting electrolyte effects, it was determined that the frozen açaí pulp extract presented an EQI of about 2.3 µA/V. Similarly, the concept of the EQI was extended to the use of the differential pulse voltammetry profile of a 0.2% ethanolic açaí extract on different supporting electrolytes, which showed that some experimental conditions needed improvement. Still, maintaining pH with a buffer solution in the anodic region is crucial to ensure reproducibility. The antioxidant capacity was also determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical assay to compare the electrochemical results. The Folin–Ciocalteu colorimetric test was applied to determine the total phenolic content of the extract. Full article

Poly(lactic acid) (PLA) is an aliphatic polyester considered a “green” material due to its natural-based origin and biodegradable properties. This is why PLA fibres may be compared with poly(ethylene terephthalate) (PET) fibres in an effort to partially replace the latter in industrial production. The purpose of this study is to investigate the dyeability of poly(lactic acid) fibres using six (6) commercially available disperse dyes with different energy levels, molecular weights and chemical structures, namely Disperse Red 59 (Serisol Fast Pink RFL), Disperse Red 60 (Serilene Red 2BL), Disperse Red 92 (Serilene Red TBLS), Disperse Orange 31 (Serisol Br Orange RGL), Disperse Yellow 54 (Serilene Yellow 3GL) and Disperse Blue 79 (Serilene Navy Blue GRLS). The dyeing characteristics, such as dye exhaustion, colour strength (K/S value), colorimetric values, wash fastness, light fastness and sublimation fastness of dyed fibres, were examined at dyeing temperatures of 110 and 130 °C, while the presence of carrier agent was also investigated. The dye exhaustion values of PLA fibres were found to be lower than those of PET fabrics; however, K/S values were higher than those of the corresponding PET fabrics in some cases. Dyed PLA fibres illustrated good colour fastness, light fastness and sublimation fastness properties, comparable to similarly dyed PET fibres. Full article

Biological hydrogels are widely available in terms of raw material sources and can be processed and molded using relatively simple techniques. Hydrogels can offer abundant three-dimensional, water-containing channels that facilitate the reaction between gases and dye, making them the preferred choice for the solid support layer in colorimetric indicators. However, biomass hydrogels exhibit inferior mechanical properties, making them unsuitable for large-scale manufacturing processes. In this study, four dual-network composite hydrogels Agar/Gelatin, Sodium Alginate/Agar, Sodium Alginate/Poly (vinyl alcohol), Sodium Alginate/Gelatin (AG/Gel, SA/AG, SA/PVA and SA/Gel) prepared through hybrid strategies. Furthermore, the influence of the dual-network structure on the mechanical properties and ammonia response was systematically investigated, using microscopy and Fourier transform infrared spectroscopy (FTIR) characterization method. The experimental results demonstrate that the incorporation of SA into original hydrogel matrices can significantly enhance both the mechanical and ammonia response performance due to the secondary topological network structure. The interpenetrating double network structure was effectively regulated through the calcium ion cross-linking process. The color difference threshold of SA/PVA’s response to ammonia gas is 10, it holds promise for rapid detection applications. The SA/Gel composite hydrogel exhibits excellent mechanical robustness and toughness. The tensile strength of the SA/Gel sample is 11 times that of a single gel, and the toughness is 80 times greater, suggesting its suitability for large-scale manufacturing of colorimetric indicator. Full article

Over a decade ago, WHO introduced the ASSURED (Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free, and Deliverable to end-users) criteria to guide diagnostic assay development. Today, lateral flow assays (LFAs) best meet these standards, evolving from simple rapid tests to advanced diagnostics integrating AI and nanotechnology for precise, quantitative results. Notably, nanoparticle-enhanced LFAs have achieved limits of detection (LOD) as low as 0.01 pg/mL (a 100-fold improvement over conventional methods), while AI algorithms have reduced interpretation errors by 40% in low-contrast conditions. The COVID-19 pandemic underscored the societal impact of LFAs, with over 3 billion antigen tests deployed globally, demonstrating 98% specificity in real-world surveillance. Beyond infectious diseases, LFAs are revolutionizing cancer screening through liquid biopsy, achieving a 92% concordance rate with gold-standard assays, food safety and environmental monitoring. Despite these advancements, challenges remain in scalability, reproducibility, sustainable manufacturing, and how to enhance the sensitivities and lower the LOD. However, innovations in biodegradable materials, roll-to-roll printing, CRISPR-integrated multiplexing, and efficient functionalization methods like photochemical immobilization technique offer promising solutions, with projected further cost reductions and scalability. This review highlights the technological evolution, diverse applications, and future trajectories of LFAs, highlighting their critical role in democratizing diagnostics. Full article

Transparent Exopolymer Particles (TEP) play a key role in the marine carbon cycle, facilitating the aggregation and exportation of organic matter. TEP production is particularly relevant during Harmful Algal Blooms (HABs), where dinoflagellates like Lingulaulax polyedra can release significant amounts of exudates. Temperature is a crucial environmental factor that influences HAB dynamics and physiological processes of bloom-forming species, affecting exudate composition and abundance. This study investigates the influence of temperature and nutrient availability on the production of organic exudates in L. polyedra cultures. TEP, Particulate Organic Carbon (POC), and Particulate Organic Nitrogen (PON) concentrations were analyzed under controlled laboratory conditions. Batch cultures were maintained at temperatures of 17, 20, and 25 °C, with two nutrient regimes (low and high nitrate and phosphate concentrations). Exudates were quantified using colorimetric and spectrophotometric methods. We found that temperature and nutrient availability significantly influence exudate production. The highest TEP concentration was recorded at 25 °C in cells cultivated under low-nutrient conditions, whereas POC exhibited a notable increase at 20 °C. ANOVA revealed that TEP and POC were the primary drivers of variability among treatments. These findings reveal that temperature is important in the regulation of L. polyedra exudate production. The role of this variable on organic matter cycling and bloom dynamics in marine ecosystems is discussed. Full article

Aminoglycoside antibiotics (AGs) are widely used in medicine and animal husbandry, but they pose significant risks due to residual toxicity and antibiotic resistance. In this study, a novel chemical sensor based on the laccase-like activity of CH₃COOAg was developed for the selective detection of AGs. CH₃COOAg exhibited varying degrees of laccase-like activity in different buffers (MES, HEPES, and NaAc) and H₂O, and five AGs showed distinct intensities of the inhibitory effect on the laccase-like activity of CH₃COOA in different buffers and H₂O. Therefore, a four-channel colorimetric sensor array was constructed in combination with the use of principal component analysis (PCA) and Hierarchical Cluster Analysis (HCA) for the efficient identification of five AGs (0.02–0.3 μM) in environment samples like tap and lake water. In addition, a colorimetric method was developed for kanamycin (KAN) detection in a honey sample with a linear range of 10–100 nM (R² = 0.9977). The method has excellent sensitivity with a limit of detection of 3.99 nM for KAN. This work not only provides a rapid and low-cost detection method for AG monitoring but also provides a reference for the design of non-copper laccase mimics. Full article

Background/Objectives: This study evaluated a novel PET tracer, ⁶⁸Ga-NOTA-CYT-200, which targets human granzyme B (GZB) as a biomarker for cytotoxic T-cell activation in a clinically relevant model of melanoma-bearing mice with a humanized immune system treated with immune checkpoint inhibitor (ICI) therapy. Methods: The binding affinity of the tracer was determined using an enzymatic colorimetric assay. Tumor-bearing humanized NSG mice underwent PET imaging before and during ICI monotherapy or combination therapy to assess ⁶⁸Ga-NOTA-CYT-200 uptake within tumors and other organs. The tumor growth was carefully monitored. The treatment response was evaluated based on the percentage change in tumor size at days 5 and 15 after the treatment started. A tracer biodistribution study and immunohistochemical staining of the tumors and organs were also performed. Results: The inhibition constant (Ki) of ⁶⁸Ga-NOTA-CYT-200 was estimated at 4.2 nM. PET imaging showed a significantly higher ⁶⁸Ga-NOTA-CYT-200 uptake in mice receiving the combination therapy compared to those receiving monotherapy or a vehicle (p < 0.0001 or p = 0.0005, respectively), which correlated with the greatest reduction in tumor size in the combination ICI group. Regardless of treatment, the responders presented with a significantly higher ⁶⁸Ga-NOTA-CYT-200 uptake at days 4 or 7 after the treatment began (p = 0.0002 and p = 0.0109, respectively). An increased uptake of ⁶⁸Ga-NOTA-CYT-200, especially in the intestines and liver within the combination ICI group, suggested immune-related adverse events (IrAEs). Conclusions: Our study demonstrates that ⁶⁸Ga-NOTA-CYT-200 PET imaging can predict the early treatment response in melanoma models treated with ICI and may also help in detecting IrAEs. Full article