Search Results (255)

Monitoring nitrate levels in water is critical to protect public health and ensure compliance with regulatory standards. This study provides a comprehensive evaluation of four analytical techniques—test strips, ion-selective electrodes (ISE), colorimetric methods, and titration—to assess nitrate levels in a variety of water sources, including standard solutions, rainwater, bottled water, and groundwater from both shallow and deep wells located in semi-urban regions of Saudi Arabia. Each method was assessed for sensitivity, accuracy, detection limits, reproducibility, and operational practicality. Test strips offer rapid, low-cost screening but consistently underestimate nitrate concentrations, particularly at low levels. The ISE demonstrated broad applicability and reliable performance across a wide concentration range when properly calibrated, making it suitable for both field and laboratory applications. Colorimetric methods provide excellent sensitivity for trace-level detection, whereas titration delivers the highest accuracy for high-nitrate samples despite its time-intensive nature. By calibrating and validating the methods against certified standards, we quantitatively demonstrated their reliability through statistical measures such as precision and accuracy rates. Moreover, the application of Geographic Information System (GIS) techniques in spatial analysis has revealed significant differences in the distribution of nitrates. Notably, shallow wells located in the northern regions surpass the 50 mg/L limit set by the World Health Organization (WHO), thereby indicating the presence of localized contamination hotspots. This study is among the first to systematically compare nitrate detection methods across a wide range of water types in a semi-urban area of Saudi Arabia. Building on a detailed analysis of each method, we underline the crucial need for the strategic selection of nitrate analysis techniques. This selection should be tailored to specific operational contexts, accuracy requirements, and concentration ranges to guide stakeholders towards more informed decision-making. These findings provide actionable guidance for public health officials and water managers to prioritize monitoring, safeguard drinking-water sources, and mitigate nitrate-related health risks in semi-urban communities. Full article

Human granulocyte colony-stimulating factor (hG-CSF) is primarily used to treat neutropenia induced by cancer chemotherapy and bone marrow transplantation. The current identification test for hG-CSF relies on Western blot (WB), a labor-intensive and technically demanding method. This study aimed to screen and prepare an anti-hG-CSF nanobody to identify and quantify hG-CSF, with the ultimate goal of developing colloidal gold-labeled nanobody test strips for rapid identification. An alpaca was immunized with hG-CSF, and the VHH gene sequence encoding the anti-hG-CSF nanobody was obtained through sequencing following phage display library construction and multiple rounds of biopanning. The nanobody C68, obtained from screening, was expressed by E. coli, and its physicochemical properties such as molecular weight, isoelectric point, and affinity were characterized after purification. WB analysis demonstrated excellent performance of the nanobody in identification tests in terms of specificity, limit of detection (LOD), applicability with products from various manufacturers, and thermal stability. Additionally, we established an ELISA method for hG-CSF quantification utilizing the nanobody C68 and conducted methodological validation. Finally, colloidal gold-based test strips were constructed using the nanobody C68, with a LOD of 30 μg/mL, achieving rapid identification for hG-CSF. This study represents a novel application of nanobodies in pharmaceutical testing and offers valuable insights for developing identification tests for other recombinant protein drugs. Full article

Chrysotila dentata (Haptophyta), a harmful algal bloom (HAB) species frequently occurring in coastal waters of China, is one with strong environmental adaptability that poses a serious threat to marine ecosystems and fisheries. Current molecular detection techniques and early warning systems for this species remain limited. To address this, we developed a rapid and highly sensitive detection method for C. dentata. This method integrates recombinase polymerase amplification (RPA) with CRISPR-LbaCas12a and lateral flow dipstick (LFD) technologies, enabling visual readout of results. Key parameters, including the single-stranded DNA (ssDNA) reporter concentration, reaction time, and temperature, were systematically optimized. Field water sample testing demonstrated high specificity and sensitivity, achieving a detection limit of 5 × 10⁻⁶ pg μL⁻¹ for genomic DNA under laboratory conditions and 2.82 × 10¹ cells mL⁻¹ in simulated environmental samples. The entire detection process takes only 1 h (at a constant 39 °C), and results can be directly interpreted via LFD strips. For early warning and prevention of C. dentata outbreaks, this assay provides a powerful, reliable, and field-ready monitoring tool. Full article

The ongoing COVID-19 pandemic has underscored the urgent need for rapid, sensitive, and versatile diagnostic tools. In this study, we developed a nanogold-based lateral flow immunoassay (LFIA) capable of detecting both SARS-CoV-2 nucleocapsid (N) protein antigens and anti-N IgG antibodies at the point of care. Following optimization of colloidal gold nanoparticle size, pH, and protein conjugation parameters, LFIA strips were assembled in two formats: a competitive assay for antigen detection and a sandwich assay for antibody detection. In the competitive format, gold nanoparticles (AuNPs)-conjugated N protein were used to detect varying concentrations of free N protein. The test line signal inversely correlated with antigen concentration, confirming the assay’s specificity and effectiveness. For antibody detection, the sandwich LFIA format employed immobilized anti-human IgG to capture anti-N antibodies in serum samples from COVID-19 patients. Strong test line signals were observed in samples collected ≥11 days post-symptom onset, indicating a time-dependent increase in IgG detectability. These results demonstrate that the AuNP-based LFIA platform provides a flexible, rapid, and low-cost diagnostic solution, suitable for both early antigen detection and serological monitoring during SARS-CoV-2 infection and recovery. Full article

Background: Veterinary antibiotics are widely used in food-producing animals, raising public health concerns due to drug residues and the risk of antimicrobial resistance. Rapid and reliable detection systems are critical to ensure food safety and regulatory compliance. Colloidal gold immunoassay (CGIA)-based antigen–antibody test cards are widely used in food safety for the rapid screening of veterinary antibiotic residues. However, manual interpretation of test cards remains inefficient and inconsistent. Methods: To address this, we propose a complete AI-based detection system for veterinary antibiotic residues. The system is built on the Rockchip RK3568 platform and integrates a five-megapixel OV5640 autofocus USB camera (60° field of view) with a COB LED strip (6000 K, rated 5 W/m). It enables high-throughput, automated interpretation of colloidal gold test cards and can generate structured detection reports for regulatory documentation and quality control. The core challenge lies in achieving accurate and fast inference on resource-constrained embedded devices, where traditional detection networks often struggle to balance model size and performance. To this end, we propose VetStar, a lightweight detection algorithm specifically optimized for this task. VetStar integrates StarBlock, a shallow feature extractor, and Depthwise Separable-Reparameterization Detection Head (DR-head), a compact, partially decoupled detection head that accelerates inference while preserving accuracy. Results: Despite its compact size, with only 0.04 M parameters and 0.3 GFLOPs, VetStar maintains strong performance after distillation with the Bridging Cross-task Protocol Inconsistency Knowledge Distillation (BCKD) method. For our custom Veterinary Drug Residue Rapid Test Card (VDR-RTC) dataset, it achieves an mAP50 of 97.4 and anmAP50-95of 89.5. When deployed on the RK3568 device, it delivers results in just 5.4 s—substantially faster than comparable models. Conclusions: These results highlight the system’s strong potential for high-throughput, cost-effective, and rapid veterinary antibiotic residue screening, supporting food safety surveillance efforts. 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

The synergistic effect of using D2EHPA and TOPO together to enhance the extraction of samarium(III) from aqueous media via emulsion liquid membrane (ELM) technology was explored. D2EHPA in binary mixtures with TBP and in ternary mixtures with TOPO and TBP was also tested. Among the tested extractants, a binary mixture of 0.1% (w/w) D2EHPA and 0.025% (w/w) TOPO achieved 100% samarium(III) extraction at a low loading. This mixture outperformed D2EHPA-TBP and other systems because D2EHPA strongly binds to Sm(III) ions, while TOPO increases the solubility and transport efficiency of metal complexes. Additionally, process factors that optimize performance and minimize emulsion breakage were examined. Key insights for successfully implementing the process include the following: 5 min emulsification with 0.75% Span 80 in kerosene at pH 6.7 (natural), 250 rpm stirring, a 1:1 internal/membrane phase volume ratio, a 20:200 treatment ratio, and a 0.2 N HNO₃ stripping agent. These insights produced stable, fine droplets, enabling complete recovery and rapid carrier regeneration without emulsion breakdown. Extraction kinetics accelerate with temperature up to 35 °C but declined above this limit due to emulsion rupture. The activation energy was calculated to be 33.13 kJ/mol using pseudo-first-order rate constants. This suggests that the process is diffusion-controlled rather than chemically controlled. Performance decreases with Sm(III) feed concentrations greater than 200 mg/L and in high-salt matrices (Na₂SO₄ > NaCl > KNO₃). Integrating these parameters yields a scalable, low-loading ELM framework capable of achieving complete Sm(III) separation with minimal breakage. Full article

The rapid development of transportation infrastructure in mountainous terrains, soft-soil foundations, and high-fill embankments poses stability challenges for conventional embankments, driving the application of advanced three-dimensional reinforced soil technologies. Geogrid with Strengthened Nodes (GSN) is one such innovation, forming a three-dimensional structure by placing block-shaped nodes at geogrid rib intersections. Current research on GSN focuses mainly on pullout tests and numerical simulations, while model-scale studies of its load-bearing deformation behavior and soil pressure distribution remain scarce. This study presents laboratory model tests to assess the reinforcement performance of GSN-reinforced embankments under static and dynamic strip loads. Under static loading, the ultimate bearing capacity of GSN-reinforced embankments increased by 74.58% compared with unreinforced cases and by 26.2% compared with conventional geogrids. Under dynamic loading, cumulative settlement decreased by 32.82%, and lateral displacement at the slope crest was reduced by 64.34%. The strengthened node design improved soil shear strength and controlled lateral deformation via enhanced lateral resistance, creating a more stable “reinforced zone” that alleviated local stress concentrations. Overall, GSN significantly enhanced embankment bearing capacity and stability, outperforming traditional geogrid reinforcement under both static and dynamic conditions, and providing a promising solution for challenging geotechnical environments. Full article

Due to the severe hazard of aflatoxins (AFs) to humans, it is of great significance to detect the key aflatoxins, aflatoxin B₁ (AFB₁) and aflatoxin G₁ (AFG₁), in food and feed in simple, rapid, and semi-quantitative ways. The hybridoma clone 3A1 was prepared in this study, and anti-AFB₁ monoclonal antibody (mAb) with high specificity and affinity (9.38 × 10⁸ L/mol) from 3A1 was purified. The indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) demonstrated that the linear detection range for AFB₁ was 0.029–1.526 ng/mL with a limits of determination (LOD) of 0.023 ng/mL. A latex microsphere-based immunochromatographic test strip (LM-ICTS) was constructed based on 3A1, which showed that the strip could detect AFB₁ (LOD: lower than 1.79 ng/mL) and AFG₁ (LOD: lower than 8.08 ng/mL), and the linear detection ranges for AFB₁ and AFG₁ are 1.79–48.46 ng/mL and 8.08–107.40 ng/mL, respectively. The average recoveries of intra-assay and inter-assay for peanuts were (98.4 ± 4.7)% and (92.6 ± 7.6)%, and the average coefficient of variation (CVs) were 4.38% and 8.15%, respectively. For sunflower seeds, the intra-assay and inter-assay recoveries were (94.4 ± 7.2)% and (89.2 ± 4.3)%, and the average CVs were 6.6% and 4.9%, respectively. In summary, the developed LM-ICTS exhibited excellent sensitivity and specificity, which provided a rapidly stable on-site detection choice for AFB₁ and AFG₁ to contaminated agricultural samples, including grain and feed. Full article

Pseudomonas fluorescens is the main spoilage bacterium in milk, and its proliferation is one of the factors leading to the deterioration of the quality of raw milk. In this study, a rapid detection system for P. fluorescens was developed based on recombinase-aided amplification combined with a test strip (RAA-TS), which contained a double test line (DTL) targeting the virulence gene aprX of P. fluorescens and the housekeeping gene gyrB of Pseudomonas. Visual observation could detect gyrB (50 CFU/mL) and aprX (250 CFU/mL) within 90 min, including sample pretreatment and RAA reaction and detection steps. No cross-reactions were observed with Pseudomonas or other bacteria (n = 19). The quantitative detection limits (LOD) of gyrB and aprX for P. fluorescens in milk were 37 CFU/mL and 233 CFU/mL, respectively. Compared with polymerase chain reaction-agarose gel electrophoresis (PCR-AGE), the sensitivity of the developed RAA-TS-DTL system was increased by approximately four times. Furthermore, it could detect live P. fluorescens in milk when combined with optimized sample pretreatment by propidium monoazide (PMAxx). Its consistency with the traditional culture method in the detection of P. fluorescens spiked in milk samples (n = 25) was 100%. The developed RAA-TS-DTL had the advantages of high accuracy and short time consumption. Thus, it provides a new way or tool for the rapid screening or detection of P. fluorescens in milk. Full article

The growing demand for ultra-low sulfur fuels has intensified interest in recovering strategic metals from the large volumes of hazardous hydrodesulfurization catalysts that are discarded yearly. This work evaluates a task-specific ionic liquid, tri-n-octylammonium bis(2-,4-,4-trimethylpentyl)-phosphinate [TOA][Cy272], synthesized by the acid–base neutralization of tri-n-octylamine and Cyanex 272. FT-IR spectroscopy confirmed complete proton transfer and the formation of a stable ion pair. Liquid–liquid extraction tests were conducted with synthetic Co–Ni–Mo solutions (0.1–2.5 g/L each), a varying ionic liquid concentration (10–50 vol%), pH (1.5–12.5), and organic/aqueous ratio (1:1). At 35 vol% of ionic liquid and pH 2, the extraction efficiency for Mo reached 94%, with separation factors βMo/Ni = 12 and βMo/Co = 7.5; Co and Ni uptake remained ≤15%. Selectivity decreased at higher metal loadings because of ionic liquid saturation, and an excessive ionic liquid amount (>35%) offered no benefit, owing to viscosity-limited mass transfer. Stripping studies showed that 1 M NH₄OH stripped about 95% Mo, while leaving Co and Ni in the organic phase; conversely, 2 M HCl removed 92–98% of Co and Ni, but <5% Mo. Overall Mo recovery of about 95% was obtained by a two-step extraction/stripping scheme. The results demonstrate that [TOA][Cy272] combines the cation exchange capability of quaternary ammonium ILs with the strong chelating affinity of organophosphinic acids, delivering rapid, selective, and regenerable separation of Mo from mixed-metal leachates and wastewater streams. Full article

Straw fiber curtain contains a plant fiber blanket woven from crop straw, which is mainly used to protect embankment slopes from rainwater erosion. To investigate the erosion control performance of slopes covered with straw fiber curtains of different structural configurations, physical model tests were conducted in a 95 cm × 65 cm × 50 cm (length × height × width) test box with a slope ratio of 1:1.5 under controlled artificial rainfall conditions (20 mm/h, 40 mm/h, and 60 mm/h). The study evaluated the runoff characteristics, sediment yield, and key hydrodynamic parameters of slopes under the coverage of different straw fiber curtain types. The results show that the A-type straw fiber curtain (woven with strips of straw fiber) has the best effect on water retention and sediment reduction, while the B-type straw fiber curtain (woven with thicker straw strips) with vertical straw fiber has a better effect regarding water retention and sediment reduction than the B-type transverse straw fiber curtain. The flow of rainwater on a slope covered with straw fiber curtain is mainly a laminar flow. Straw fiber curtain can promote the conversion of water flow from rapids to slow flow. The Darcy-Weisbach resistance coefficient of straw fiber curtain increases at different degrees with an increase in rainfall time. Full article

γ-Glutamyl transpeptidase (GGT) is overexpressed in a variety of diseases, making it an important diagnostic criterion for diseases. Herein, a new fluorescence probe based on naphthalimide (Glu-MDA) was developed and employed for the rapid detection of GGT in tumor cells or samples. Alkynylated naphthalimide is the fluorescent core for excellent fluorescence response. The covalent bridging of self-immolative short linkers reduces the steric hindrance between probes and enzyme cleavage sites, which leads to improved enzymatic reaction kinetics. Glu-MDA shows a rapid response and excellent selectivity with a detection limit of 0.044 U/L. This allows the efficient detection of GGT levels in solution and cells. Simultaneously, the construction of Glu-MDA pre-stained test strips provided an innovative strategy for the qualitative detection of GGT activity, helping to detect GGT faster, more portably, and cost-effectively in various scenarios. Full article

Highly infectious and pathogenic viruses seriously threaten global public health, underscoring the need for rapid and accurate diagnostic methods to effectively manage and control outbreaks. In this study, we developed a comprehensive Surface-Enhanced Raman Scattering–Lateral Flow Immunoassay (SERS-LFIA) detection system that integrates SERS scanning imaging with artificial intelligence (AI)-based result discrimination. This system was based on an ultra-sensitive SERS-LFIA strip with SiO₂-Au NSs as the immunoprobe (with a theoretical limit of detection (LOD) of 1.8 pg/mL). On this basis, a negative–positive discrimination method combining SERS scanning imaging with a deep learning model (ResNet-18) was developed to analyze probe distribution patterns near the T line. The proposed machine learning method significantly reduced the interference of abnormal signals and achieved reliable detection at concentrations as low as 2.5 pg/mL, which was close to the theoretical Raman LOD. The accuracy of the proposed ResNet-18 image recognition model was 100% for the training set and 94.52% for the testing set, respectively. In summary, the proposed SERS-LFIA detection system that integrates detection, scanning, imaging, and AI automated result determination can achieve the simplification of detection process, elimination of the need for specialized personnel, reduction in test time, and improvement of diagnostic reliability, which exhibits great clinical potential and offers a robust technical foundation for detecting other highly pathogenic viruses, providing a versatile and highly sensitive detection method adaptable for future pandemic prevention. Full article

Heavy metal ions pose a significant threat to the environment and human health due to their high toxicity and bioaccumulation. Traditional instrumentations, although sensitive, are often complex, costly, and unsuitable for on-site rapid detection of heavy metal ions. Lateral flow assay technology has emerged as a research hotspot due to its rapid, simple, and cost-effective advantages. This review summarizes the applications of lateral flow assay technology based on nucleic acid molecules and antigen–antibody interactions in heavy metal ion detection, focusing on recognition mechanisms such as DNA probes, nucleic acid enzymes, aptamers, and antigen–antibody binding, as well as signal amplification strategies on lateral flow testing strips. By incorporating these advanced technologies, the sensitivity and specificity of lateral flow assays have been significantly improved, enabling highly sensitive detection of various heavy metal ions, including Hg²⁺, Cd²⁺, Pb²⁺, and Cr³⁺. In the future, the development of lateral flow assay technology for detection of heavy metal ions will focus on multiplex detection, optimization of signal amplification strategies, integration with portable devices, and standardization and commercialization. With continuous technological advancements, lateral flow assay technology will play an increasingly important role in environmental monitoring, food safety, and public health. Full article