Search Results (1,433)

The increasing demand for advanced diagnostic technologies has positioned biosensor platforms as powerful alternatives to conventional analytical methods. Among them, lateral flow platforms (LFPs) are widely used for their speed, simplicity, and low cost. However, their limited sensitivity and lack of quantitative precision have spurred the development of enhanced systems incorporating electrochemical detection. Electrochemical biosensors offer significant advantages, including high sensitivity, excellent selectivity, and ease of miniaturization, which make them especially suitable for point-of-care testing (POCT). To address the limitations of traditional colorimetric LFPs, several strategies have been employed, such as the incorporation of nanomaterials, enzymatic amplification, and signal-enhancing labels. A particularly promising innovation is the direct integration of electrodes into LFPs, enabling real-time electrochemical readouts and enhanced analytical accuracy. Despite their potential, challenges persist, including manufacturing complexity, a lack of standardized protocols, and difficulties in scaling production for widespread adoption. Continued progress in developing hybrid platforms that combine lateral flow technology with electrochemical detection is crucial for expanding diagnostic applications in healthcare, environmental monitoring, and food safety. This work explores recent advances in electrochemical LFPs, reviewing current methodologies while discussing their advantages, limitations, and the future directions necessary to facilitate broader implementation and improve global diagnostic accessibility. Full article

Sensitive detection of Escherichia coli O157:H7 (E. coli O157:H7) in food matrices remains an important analytical challenge. Here, a colorimetric biosensor was constructed based on a bimetal oxide nanozyme composed of Ce-Fe oxide. This biosensor achieved sensitive detection of E. coli O157:H7. The Ce-Fe oxide synthesized on the basis of deep eutectic solvents (DESs) had the advantages of low solvent consumption and short preparation time. By regulating the two key factors of metal valence and oxygen vacancy content, the peroxidase (POD) activity of the nanozyme was significantly improved. Compared with the single-metal oxide nanozyme Fe oxide, the addition of Ce increased the Fe²⁺/Fe³⁺ ratio from 0.37 to 0.49, implying a possible enhancement of electron transfer between Fe²⁺ and Fe³⁺. The detection limits (LODs) of the biosensor based on Fe oxide and that based on Ce-Fe oxide were 10² CFU/mL and 10¹ CFU/mL, respectively, comparable to existing validated methods. Moreover, these two biosensors achieved satisfactory recovery rates (91–104%) and RSDs (1.2–8.8%) in the spiked lake water, juice, and lettuce samples of E. coli O157:H7, indicating their high potential for application in spiked sample detection. In summary, the method proposed in this study for improving the POD activity of nanozymes through electron transfer in DES solutions is beneficial to the development of metal oxide nanozymes. Full article

The development of effective fluorescent probes for the detection of acids and bases, both in solution and in the solid state, is of particular interest worldwide, due to the possibility of preventing hazardous consequences for human health and the environment. In the present work, the synthesis of a 1,8-naphthalimide derivative, designed as a “fluorophore-receptor₁-spacer-receptor₂” model, is considered. The compound contains two receptors for analytes in one molecule and can operate as a fluorescent probe via PET and ICT mechanisms. The photophysical behavior of the synthesized derivative in solution, on strip paper, and in thin film was investigated. It was found that the transition from acidic to alkaline medium in solution is associated with a change in color that is visible with the naked eye (yellow–orange-red–blue). The change in fluorescence, both in solution and spread on a supporting surface (strip paper and thin film), can be spectrophotometrically observed. The influence of various volatile acids on the sensing activity of the synthesized compound in solution and deposited on a solid support was investigated. It was found that with increasing acid strength, the fluorescence intensity increases. The strip paper and thin film obtained with the synthesized compound show reversible switching between the “off” and “on” states of fluorescence. The strip paper exhibited good cycling under acid–base vapor stimulation. The results obtained demonstrate the possibility of application of the synthesized compound as a colorimetric and fluorescent probe for determination of pH in solution, and detection of acids, bases, and their vapors in indoor and outdoor residential and industrial premises, as well as in the environment. Full article

Background/Objectives: Onion (Allium cepa) peems are an underutilized by-product rich in polyphenols. This study evaluated the physicochemical profile, and bioactive potential (antidiabetic, antimicrobial, antioxidant, and anticoagulant) of Moroccan red onion peels using integrated in vivo, in vitro, and in silico approaches. Methods: Moisture, pH, ash content, and mineral elements were determined, followed by phytochemical screening and three extractions: decoction E0, aqueous Soxhlet E1, and hydroethanolic Soxhlet E2 (70/30; ethanol/water, v/v). The measurement of polyphenols, flavonoids, and tannins was carried out using colorimetric methods, while the molecular profile was studied by high-performance liquid chromatography coupled to ultraviolet detection and electrospray ionization mass spectrometry (HPLC/UV-ESI-MS). Biological activities were determined using 2,2-diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power, and total antioxidant capacity assays (in vitro antioxidant); microdilution (antimicrobial); prothrombin time and activated partial thromboplastin time (anticoagulant); and α-amylase/α-glucosidase enzymatic inhibition and oral glucose tolerance tests on normoglycemic rats. Also, acute toxicity was evaluated, and molecular interactions between these proteins and ligands (docking, molecular dynamics, and MM-PBSA) were analyzed. Results: Physicochemical analyses showed an acidic pH (3.06) and high ash content (15.21%), with the concentration of regulated elements remaining within FAO/WHO limits. The extractive content was between 6.90% E0 and 19.18% E2. The E1 extract had the maximum amount of total polyphenols (178.95 mg GAE/g); on the other hand, E2 was the richest in flavonoids by 121.43 mg QE/g. The HPLC/ESI-MS analysis of E0 revealed 20 compounds, among which flavonoids (84.93%) were predominant, with isorhamnetin (30.26%), followed by quercetin and its glycosylated forms. E1 showed the most potent antioxidant effects (IC₅₀ DPPH, 22.38 µg/mL, as that of ascorbic acid). The antibacterial activity of E0 was especially potent towards Enterobacter cloacae and Pseudomonas aeruginosa (MIC 75 µg/mL). A mild dose-dependent anticoagulant effect was seen. Antidiabetic activity was found to be outstanding: α-amylase (IC₅₀ 62.75 µg/mL) and α-glucosidase (IC₅₀ 8.49 µg/mL, stronger than acarbose) inhibitions were corroborated in vivo by a considerable decrease in the glycemic area under the curve. The molecular docking study in silico demonstrated strong molecular interactions, especially for quercetin 4′-O-glucoside with good binding energies. Conclusions: A. cepa peels from Morocco can be considered a safe plant matrix containing bioactive flavonoids with strong antioxidant and selective antimicrobial activities and promising antidiabetic effects, supported by molecular modeling. Full article

Streptococcus suis is a serious zoonotic pathogen responsible for rapid progression and deadly infections in both humans and pigs. With an increasing number of reported cases and considering the limitations of standard routine identification, a simple, rapid, and cost-effective approach is needed. In this study, a label-free colorimetric assay based on gold nanoparticles (AuNPs) was applied with a specific aptamer, R8-su12. This assay offered simplified detection through observable color change, enabling visual analysis by the naked eye or assessment via UV–Vis spectrophotometry. Under the optimal assay conditions, the detection procedure was carried out within 45 min. The reaction of the aptasensor and other bacterial species, including Staphylococcus aureus, S. pneumoniae, S. pyogenes, Pseudomonas aeruginosa, Escherichia coli, Enterococcus faecium, and E. faecalis, was not present, indicating the specificity of this assay. Moreover, the aptasensor exhibited high sensitivity with a limit of detection (LOD) at 1 CFU of S. suis and had broad reactivity with S. suis serotypes 1, 1/2, 9, and 14, as well as with S. suis isolated from clinical specimens. Thus, this aptasensor demonstrates proof-of-concept feasibility including clinical sample testing before practical implementation. It holds promise as a practical tool for the early screening and outbreak management of S. suis in a variety of settings, such as clinical laboratories, food safety, and the environment. Full article

Background/Objectives: This study aimed to describe and quantify facial soft tissue changes in two patients who underwent radiotherapy (RT) for head and neck cancers, using three-dimensional (3D) stereophotogrammetry and surface deviation analysis. The aims were (i) to assess the progression of morphological alterations over time (ii) and to evaluate the clinical potential of 3D surface mapping in documenting RT-related aesthetic changes. Methods: Two patients with head and neck cancer undergoing RT were analyzed using three-dimensional stereophotogrammetry (3dMD Trio-system, Atlanta, GA, USA) at three timepoints: before RT (T0), 45 days after the start of RT (T1), and 6 months after the start of RT (T2). Facial 3D scans were processed using Geomagic Control 2014 software (v.3D Systems, Morrisville, NC, USA) to perform standardized alignments and calculate volumetric deviations, create colorimetric deviation maps, and conduct Root Mean Square (RMS) analysis. Results: Between T0 and T1, both patients showed soft tissue volume reduction, primarily in the mandibular and submental regions, likely reflecting acute treatment effects and weight loss. Between T0 and T2, an increase in soft tissue volume was observed, especially in the lower face and neck, consistent with late radiation effects such as lymphedema and post-treatment weight gain. RMS values ranged from 5.53 mm to 6.87 mm across patients and time points, indicating measurable morphological changes. The upper third of the face remained stable and served as a reliable reference region for alignment. Conclusions: RT may be associated with significant, region-specific changes in facial and cervical soft tissues in HNC patients, but these preliminary observations must always be correlated with weight loss and confirmed by further studies. 3D stereophotogrammetry is a reliable, non-invasive method for detecting and quantifying these alterations over time. This technique can offer valuable insights for clinical monitoring and could promote better patient counseling and potentially mitigate the psychological burden associated with facial changes. Full article

Background/Objectives: Rapid, equipment-free molecular detection of bacterial pathogens at the point of care (POC) remains a critical challenge. Staphylococcus aureus is a leading cause of severe infections, necessitating simple and sensitive diagnostic tools. Methods: We developed an integrated assay combining helicase-dependent amplification (HDA) and rolling circle amplification (RCA) in a sequential ‘one-pot’ format. Asymmetric HDA generates short, single-stranded amplicons from S. aureus DNA, enabling specific padlock probe ligation and subsequent exponential RCA. For equipment-free visual detection, biotin-labeled nucleotides are incorporated during RCA, and products are captured on a silica membrane and detected using a streptavidin-HRP conjugate with 3,3′,5,5′-tetramethylbenzidine substrate, producing an unambiguous blue color. Results: The assay detected as few as 10¹ genome copies of S. aureus per reaction. Evaluation against a panel of nine non-target respiratory pathogens and human genomic DNA demonstrated 100% specificity, with no cross-reactivity. The entire procedure is performed isothermally at 65 °C in a single tube with a total assay time of approximately 90 min. Conclusions: This ‘one-pot’ HDA-RCA colorimetric assay combines high sensitivity and specificity for S. aureus in a user-friendly, almost equipment-free format. Its simplicity and robust visual readout make it a promising tool for POC diagnostics in resource-limited settings, enabling rapid clinical decisions without specialized instrumentation. Full article

Antibiotic residues in aquatic products pose a serious food safety concern, whereas conventional laboratory methods often fail to meet the demand for on-site rapid screening. This study systematically reviews the research progress from 2021 to 2025 on both the risks of antibiotic residues in aquatic products and the development of rapid on-site detection technologies. First, based on a literature survey covering major aquatic products (e.g., fish, shrimp, and shellfish), the widespread occurrence of multiple antibiotics at high concentrations was documented, with quinolones and sulfonamides identified as the most frequently detected classes. To address the need for on-site testing, this review focuses on six rapid detection techniques: fluorescent sensor (FRS), lateral flow immunoassay (LFIA), surface-enhanced Raman scattering (SERS), enzyme-linked immunosorbent assay (ELISA), electrochemical sensor (ECRS), and colorimetric sensor (CRS). The core principles, technical advantages, recent application cases (e.g., integration with smartphones and novel nanomaterials), and development trends for each method are analyzed. Finally, it discusses the current challenges faced by existing on-site detection approaches and their potential solutions. Technology selection strategies tailored to different application scenarios (e.g., aquaculture farms, distribution channels, and consumer-level use) are also proposed. Full article

Owing to the high stability and low cost of nanozymes, they have been extensively investigated and reported. In this work, highly active CeO₂ nanoflowers were first prepared and then different metal elements were doped into the CeO₂ nanoflower matrix via a novel synthesis method to fabricate M-CeO₂ (M = Cu, Fe, Co, Mn, La) nanomaterials. Mn-CeO₂ with the highest peroxidase-like activity was selected via systematic screening, the as-prepared Mn-CeO₂ nanocomposites exhibited enhanced enzyme-like activity due to the strong metal-support interaction. This article explored the effects of doping ratio, pH, temperature, reaction time, and material concentration on its activity. A simple sensitive and selective colorimetric method was established and successfully used to detect hydrogen peroxide and ascorbic acid sensitively. When the hydrogen peroxide (H₂O₂) concentration is within the 2.0–120.0 μM range, the UV-visible absorbance at 652 nm was associated linearly with the H₂O₂ concentration, R² = 0.9959, LOD = 1.7 μM (S/N = 3). The absorbance of the reaction system showed a good linear relationship with the ascorbic acid (AA) concentration (1.0–40.0 μM, R² = 0.992), LOD = 0.98 μM (S/N = 3). This study provides an effective way to construct efficient nanozymes and their potential applications in sensing and detection. Full article

Background/Objectives: Lamiaceae species are valuable sources of bioactive natural products, often associated with anti-infective properties. This study investigated chemical composition and bioactivities of dry hydroethanolic extracts and essential oils from Micromeria nervosa (Desf.) Benth. aerial parts from two localities. Methods: Extracts and essential oils were analyzed using LC-DAD-QTOF-MS/MS and GC-FID/MS, respectively. Antimicrobial activity was assessed against 14 strains (microdilution method), and antiviral activity against three viruses by determining cytopathic effects, viral titers (end-point dilution assay) and viral loads (qPCR/RT-qPCR). Cytotoxicity was evaluated on three cancer cell lines (MTT assay) and antioxidant potential using three colorimetric tests. Composition–activity correlation was statistically analyzed; in silico molecular docking/dynamics simulations were performed. Results: Thirty-five compounds were annotated in extracts, including 30 reported for the first time in this species, with rosmarinic acid as the main component. Essential oils contained 31 constituents, dominated by carvacrol. Newly detected phenolics included lithospermic acid and several salvianolic and clinopodic acids. Extracts and oils exhibited notable antibacterial activity, especially against five Gram-positive strains (MIC = 0.313–2.5 mg/mL), and oils showed marked anticandidal effects (MIC = 0.313–0.625 mg/mL) and enhanced cytotoxicity against colon, gastric and hypopharyngeal cancer cells (selectivity indices ≥ 1.66). Extracts displayed potent antiviral activity against human herpesvirus 1 (HHV-1) and adenovirus Ad5, reducing cytopathic effects and viral titers, with qPCR revealing decreased HHV-1 load. In silico analysis suggested HHV-1 glycoprotein D binding. Extracts also showed strong antioxidant potential. Conclusions: These findings demonstrate that M. nervosa is a rich source of compounds with antimicrobial/antiviral, cytotoxic and antioxidant activities, warranting further research. Full article

A digital colorimetric method (ACETimage), which utilizes aldol condensation, crotonization, and resinification, was developed and validated to quantify acetaldehyde in the head fraction of Pisco distillation. The optimal conditions for the reaction were as follows: the head Pisco samples were placed in headspace vials, 20% w/w NaOH was added, and the mixture was boiled in water for 2 min. The Color Grab app was used to capture and analyze images of the reactions, with a screen brightness intensity of 0.5, within a maximum post-reaction time of 10 min. The Euclidean distance (ED-RGB) was the color parameter most sensitive to changes, showing a linear correlation with the square of acetaldehyde concentration, with R² values ranging from 0.9926 to 0.9976. The limit of detection (LOD) and limit of quantification (LOQ) for the ACETimage method were determined to be 30 and 95.3 mg/L, respectively. A significant correlation was observed between the acetaldehyde content measured using ACETimage and gas chromatography (Spearman’s r = 0.9373). Bland–Altman analysis indicated that the differences between the two methods were within the 95% limits of agreement. ACETimage offers a rapid, cost-effective, and user-friendly solution for monitoring acetaldehyde levels during Pisco distillation, enabling easy implementation in production environments, both artisanal and industrial, with minimal sample preparation and limited personnel training. Full article

Food safety requires real-time monitoring of mycotoxins in food, as food products contaminated with these toxins poses major threat to human health. In this study, we proposed a remote-controlled microfluidic platform (RCMP) integrated with chemiluminescent/colorimetric detection system for rapid, cost-effective and real-monitoring of multiple mycotoxins in real samples based on the indirect competitive enzyme-linked immunosorbent assay (ic-ELISA). The RCMP enabled sensitive and automatic detection of deoxynivalenol (DON), zearalenone (ZEA), and fumonisin B1 (FB1) in the range of 4–128 ng/mL, 1–32 ng/mL, and 0.5–16 ng/mL, respectively. The limits of detection (LOD) were 2.881 ng/mL for DON, 0.702 ng/mL for ZEA, and 0.470 ng/mL for FB1. In further validation, satisfactory recoveries between 93.57% to 108.47% with the relative standard deviations (RSDs) of 6.92–11.39% were obtained in beer samples. Overall, RCMP provides an automatic, high-throughput and cost-effective method for detection of DON, ZEA, and FB1 and can be confidently applied for monitoring in beer samples. Full article

Water supplies contaminated by heavy metals pose a serious threat to human health, especially in areas without access to centralized testing facilities. While copper is a necessary heavy metal in trace levels, high concentrations can have detrimental effects on health, such as oxidative stress, cognitive impairment, and liver damage. Due to their expense, complexity, and reliance on laboratories, conventional detection techniques are accurate but unsuitable for real-time, dispersed deployment. Machine learning offers a potent solution to these constraints by facilitating the automatic, precise, and quick interpretation of complicated sensor data. It makes it possible to make decisions in real time without requiring a large laboratory infrastructure. In this work, a dual-mode optical sensor was developed using the colorimetry and fluorometry images of carbon dots embedded in hydrogels with the Cu²⁺ concentration of 0, 20, 50, 100, 200, and 500 μM. Data augmentation was used to expand the RGB picture dataset for each modality, and these data were interpolated to provide responses at 1 µM intervals (0–500 µM). We trained a comprehensive set of supervised machine learning models, including Logistic Regression, Support Vector Machines, Random Forest, and XGBoost, to categorize water samples into five risk-informed quality levels. The system achieved classification accuracies exceeding 96%. Furthermore, we built a simple user interface to make the system practically deployable in mobile phone. Together, these results demonstrate a scalable, interpretable, cost-effective, and quick solution for real-time water quality monitoring in resource-constrained environments. Since the proposed method focuses on classifying concentration ranges rather than precise quantification, a formal limit of detection (LOD) was not calculated; instead, the lowest concentration in the experimental dataset serves as the minimum detectable level. Full article

Dengue virus (DENV), an important mosquito-borne orthoflavivirus, represents a growing global threat due to its geographic expansion and recent outbreaks worldwide. In resource-limited endemic settings, the development of affordable diagnostic assays is needed. In this study, we developed and validated a colorimetric reverse transcription loop-mediated isothermal amplification assay (RT-LAMP) for the detection of DENV type 3 (DENV-3) using 95 previously diagnosed clinical samples from Southeastern Mexico. Primers targeting the 3′ untranslated region (3′ UTR) of DENV-3 were designed, and assay conditions were standardized. The colorimetric RT-LAMP DENV-3 system achieved a preliminary limit of detection of 1 × 10³ copies per reaction, with 90.7% sensitivity and 100% specificity. The colorimetric format enabled visual readout without specialized equipment, supporting its potential applicability in point-of-care and resource-limited settings. The developed colorimetric RT-LAMP detection for DENV-3 is intended as a rapid screening/triage tool that can trigger confirmatory testing or public-health actions. Full article

Accurate assessment of light properties is essential and is measured with photometric and colorimetric standardized methods. However, the spatial characteristic of light—harshness—remains difficult to quantify. Building on the authors’ previous work, this study presented a fully automated method for determining light source harshness based on image analysis of cast shadows in a standardized environment. The improved method eliminated the need for manual shadow segmentation by introducing algorithmic noise removal and adaptive smoothing of shadow data. The method was applied to 180 test images comprising 30 combinations of photographic light-shaping attachments (e.g., softboxes, beauty dishes, and snoots) across two light sources (halogen and xenon) and three intensity levels. The results showed that the method was capable of detecting subtle differences in shadow properties and confirmed the influence of geometry, material, and orientation of the light modifiers on harshness. In addition, the results provided quantitative insight into the influence of photographic light modifiers on the original light. Full article