Search Results (48)

The rising prevalence of Drug-Facilitated Sexual Assault (DFSA) underscores the urgent need for rapid, sensitive, and selective analytical tools. Among the most concerning substances are γ-hydroxybutyric acid (GHB) and its precursor γ-butyrolactone (GBL), both of which pose significant forensic challenges due to their rapid metabolism and narrow detection windows. While detection methods for GHB have advanced, the monitoring of GBL remains less explored. This study reports the extended application of a fluorescein-based chemosensor previously validated for GHB for the selective detection of GBL in aqueous media and synthetic saliva. The probe operates via fluorescence quenching proportional to GBL concentration, achieving detection limits well below toxicological thresholds. Mechanistic investigations reveal that the recognition process is driven by an acid–base equilibrium and the reversible opening of the fluorescein lactone ring, with the 2-aminonaphthoxazole moiety playing a pivotal role. The sensor exhibits high selectivity against common DFSA-related interferents. Furthermore, the system was integrated into a portable lateral flow assay coupled with a smartphone-based readout, providing a cost-effective and user-friendly platform. Meeting the WHO “ASSURED” criteria, this methodology represents a promising tool for forensic, clinical, and preventive applications against chemical submission. Full article

Recombinase polymerase amplification (RPA) has become a central amplification strategy for decentralized molecular diagnostics because it operates rapidly at mild temperatures and requires far less thermal control than PCR. Its analytical value increases substantially when paired with microfluidic and paper-based platforms, where sample handling, reagent delivery, amplification, and signal readout can be organized within compact, low-power, and field-compatible formats. This review examines recent progress in microfluidic and paper-based RPA systems across biomedical diagnostics, food safety testing, environmental monitoring, and One Health biosurveillance. Particular attention is given to integrated device architectures, including centrifugal chips, capillary-driven platforms, microfluidic paper-based analysis devices (μPADs), electrochemical biosensors, CRISPR-assisted assays, digital microfluidic systems, and sample-to-answer cartridges. Biomedical applications now span respiratory viruses, reproductive and emerging infections, bacterial and parasitic diseases, pharmacogenomic markers, and cancer-related biomarkers. RPA-enabled platforms are moving steadily into food safety and environmental surveillance, covering pathogen detection, seafood and dairy monitoring, agricultural disease control, antimicrobial-resistance tracking, and airborne pathogen screening. At the same time, the field is shifting toward more intelligent diagnostic formats. Smartphone imaging, artificial intelligence (AI)-assisted interpretation, digital partitioning, cloud connectivity, and automated quality control are increasingly being built into rapid testing workflows, giving these systems greater portability, consistency, and decision-making value. Despite this progress, practical deployment still depends on robust sample preparation, multiplex stability, quantitative reliability, reagent storage, scalable fabrication, and regulatory validation. Continued convergence of RPA chemistry with microfluidics, paper devices, CRISPR recognition, electrochemical readout, and data-assisted interpretation is expected to support more robust and accessible molecular diagnostic workflows. Full article

Copper ions (Cu²⁺) and intracellular biothiols are tightly coupled in cellular redox regulation, where copper–thiol coordination governs oxidative stress and metal homeostasis. However, analytical platforms capable of sequentially monitoring Cu²⁺ and biothiols within a single molecular system remain scarce. Herein, we report a coumarin-based fluorescent probe XDP that enables sequential ON–OFF–ON sensing of Cu²⁺ and biothiols through a coordination–competition mechanism. The imine (C=N) site of XDP selectively coordinates Cu²⁺, leading to fluorescence quenching arising from coordination-induced electronic perturbation and enhanced nonradiative decay. The probe exhibits a linear response toward Cu²⁺ over 1–80 μM with a detection limit of 0.108 μM. Subsequent competitive binding of biothiols (GSH, Cys, and Hcy) releases Cu²⁺ from the complex, thereby restoring fluorescence and enabling detection within 1–30 μM with submicromolar sensitivity. XDP also displays a large Stokes shift (135 nm), which minimizes spectral overlap and improves signal reliability. Notably, Cu²⁺ binding triggers a distinct color change that supports naked-eye detection and smartphone-based RGB quantification. The probe further enables visualization of Cu²⁺ and thiol-triggered signal recovery in living cells and zebrafish. This work establishes a versatile analytical platform for probing copper–thiol interactions in environmental and biological systems. Full article

Acid phosphatase (ACP) is a clinically important enzyme whose early-stage detection is hindered by its extremely low abundance, nonspecific tissue distribution, and rapid loss of activity under conventional analytical conditions. Herein, we present a target-driven in situ nanozyme synthesis strategy that enables rapid and ultrasensitive point-of-care testing (POCT) of ACP. In this approach, ACP catalyzes the hydrolysis of L-ascorbic acid 2-phosphate sesquimagnesium (AAPS), producing ascorbic acid (AA). The generated AA partially reduces Fe³⁺ ions to Fe²⁺, thereby initiating alkaline co-precipitation and in situ formation of Fe₃O₄ nanoparticles. Polyvinylpyrrolidone (PVP) stabilizes the nanoparticles and preserves catalytic accessibility, while their intrinsic magnetism allows for efficient magnetic separation to eliminate matrix interference. The resulting Fe₃O₄@PVP nanozymes display pronounced peroxidase-like activity, catalyzing hydrogen-peroxide-mediated oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB). Quantitative readout can be achieved using either spectrophotometric analysis or smartphone imaging. The sensing platform achieves a detection limit of 0.021 U/L within 40 min and demonstrates excellent sensitivity, selectivity, and operational robustness. Successful validation in human serum confirms its clinical feasibility, while smartphone-based imaging enables portable and low-cost quantification suitable for decentralized diagnostics. Collectively, this work establishes a generalizable paradigm for target-triggered nanozyme generation aimed at detecting low-abundance and labile biomarkers. Full article

Hydrogel-based optical sensors have emerged as a versatile class of analytical materials that combine soft-matter processability, tunable network chemistry, and compatibility with luminescent, colorimetric, photonic, and hybrid transduction strategies. Progress in the field is driven not by a single sensing mechanism, but by the convergence of key advances in material functionalization, embedded selectivity, operation across diverse sample matrices, mechanical and analytical robustness, and usability beyond the laboratory. Current systems include framework-integrated, nanoparticle-doped, probe-functionalized, photonic-crystal, enzyme-immobilized, and device-coupled hydrogels, reflecting growing architectural diversity and application-oriented engineering. Selectivity has likewise advanced from basic interferent screening to recognition-specific, imprinted, and pattern-discriminative formats suited to complex environmental, food, biological, and wearable settings. Evidence of stability, reusability, and deformation tolerance further suggests that many platforms are moving beyond proof-of-concept demonstrations toward credible real-world operation. At the same time, translational priorities such as portability, smartphone readout, implantable and epidermal formats, and multifunctionality spanning antimicrobial action, adsorption, anti-counterfeiting, and device integration are becoming increasingly prominent. Together, these trends show that hydrogel-based optical sensing is maturing into a materially rich, application-responsive domain. The key challenge ahead is to unify materials design, selectivity control, durability, and deployability in standardized, reproducible, and clinically or environmentally credible sensing platforms. Full article

Disinfection is essential to ensure safe drinking water and hygienic conditions in environmental, industrial, and clinical settings. However, conventional methods for monitoring free residual chlorine are often laboratory-based and not suited for decentralized analysis. Here, we report a novel paper-based colorimetric biosensing platform that translates the ISO 7393-2 standard, a method based on the reaction of chlorine with N,N-diethyl-p-phenylenediamine (DPD), into a portable and user-friendly format. The proposed device integrates the DPD chemistry within a paper architecture, enabling reagent-free operation at the point of need. The sensor provides a rapid visual readout that is detectable by the naked eye, while quantitative analysis is achieved within 3 min through smartphone-based image acquisition. This work constitutes the first implementation of the ISO standard in a portable paper-based format suitable for both environmental and clinical matrices. The sensor provided a detection limit of 12 μM for sodium hypochlorite and was successfully validated in real samples, including bottled water and exhaled breath condensate, with satisfactory recoveries. Furthermore, the stability of the paper-based sensor was assessed under storage conditions of 4 °C and room temperature (23 °C), demonstrating excellent performance over 30 days in both cases, indicating that refrigeration is not required for maintaining sensor performance. Full article

The unchecked and uncontrolled global spread of multidrug-resistant (MDR) bacteria is a serious challenge to healthcare and modern medicine, and demands diagnostic approaches that are rapid, sensitive, multiplexed, and reliable in point-of-care (POC) settings. At the interface of nanomaterials and aptamer-based biosensing, significant advances have been reported. The convergence of portable electrochemical sensing technologies, smartphone-based readout systems, and artificial intelligence (AI)- and machine learning (ML)-based data analysis is also playing a significant role in advancing this area. This perspective reflects on the most recent breakthroughs and translational developments in electrochemical nano-aptasensors for MDR bacterial detection, covering diagnostic targets and translation trends, nanomaterials advancements, aptamer engineering-integration, POC strategies and microfluidics platforms, and novel multimodal strategies that enhance accuracy, reliability, and efficiency in POC testing. Moreover, limitations and knowledge gaps in this area, as well as key considerations for sustainable development, large-scale manufacturing, and deployment of integrated electrochemical nano-aptasensors, are also highlighted. Electrochemical nano-aptasensors can pave the way for the transformation of MDR bacterial diagnosis, but need coordinated translational efforts for POC diagnostic advancements towards real-world applications. Full article

In this work, a 3D microfluidic paper-based analytical device (3D-µPAD) was developed for the smartphone-based colorimetric determination of phosphate in environmental samples. The assay relied on the formation of a blue-colored product (molybdenum blue) in the detection area of the 3D-µPAD upon reduction of the heteropolyacid H₃PMo₁₂O₄₀ formed in the presence of phosphate. A number of experimental parameters were optimized, including geometric aspects of 3D-µPADs, digitization and image processing conditions, the amount of chemicals deposited in specific areas of the 3D-µPAD, and the reaction time. In addition, the stability of the device was evaluated at three different storage temperatures. Under optimal conditions, the working range was found to be from 4 to 25 mg P/L (12–77 mg PO₄⁻³/L). The limits of detection (LOD) and quantification (LOQ) were 0.015 mg P/L and 0.05 mg P/L, respectively. The repeatability and intermediate precision of a 5 mg P/L standard were 4.8% and 7.1%, respectively. The proposed colorimetric assay has been successfully applied to phosphorous determination in various waters, soils, and sediments, obtaining recoveries in the range of 94 to 107%. The ready-to-use 3D-µPAD showed a greener profile than the standard method for phosphate determination, being affordable, easy-to-use, and suitable for citizen science applications. Full article

The widespread circulation of Eurasian avian-like H1N1 (EA H1N1) swine influenza virus poses significant zoonotic and pandemic risks worldwide. However, current diagnostic methods are difficult to deploy in the field, as they generally require specialized laboratory infrastructure and trained personnel. Here, we present a novel dual-signal detection platform that combines reverse transcription recombinase polymerase amplification (RT-RPA) with CRISPR/Cas12a technology for rapid, on-site EA H1N1 detection. We established an integrated one-tube assay by designing and optimizing RT-RPA primers targeting a conserved region of the hemagglutinin (HA) gene, together with engineered CRISPR/Cas12a guide RNAs exhibiting high specificity. The platform incorporates two complementary readout modes: real-time fluorescence monitoring and visual colorimetric detection using a smartphone. The assay shows excellent analytical specificity, with no cross-reactivity observed against other swine influenza virus subtypes or common swine pathogens, (including CSFV, PRRSV, PEDV, PCV, TGEV, and RV). The detection limit is 2 copies/μL, and the entire procedure can be completed within 30 mins using simple portable equipment. When evaluated on 86 clinical samples, the assay demonstrated 94.18% concordance with RT-qPCR. Compared with conventional diagnostic methods, this RT-RPA–CRISPR/Cas12a assay offers greater convenience and cost-effectiveness. Its strong potential for field-based rapid testing underscores promising application prospects in swine influenza surveillance and control programs. Full article

The rapid global expansion of genetically modified (GM) crops requires fast, on-site detection methods. Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated (CRISPR/Cas) systems offer a promising platform for decentralized GM organism (GMO) monitoring. This review focuses specifically on the application of this technology in agriculture and food supply chains, diverging from previous reviews centered on clinical diagnostics. We examine the mechanisms of key CRISPR effectors (e.g., Cas12a, Cas13a) and their integration into diagnostic platforms (e.g., DETECTR, SHERLOCK) for detecting transgenic elements (e.g., CaMV35S promoter). A dedicated comparison of signal readout modalities, including fluorescence, lateral flow, and electrochemical sensing, highlights their suitability for different GMO detection scenarios, from field screening to laboratory confirmation. Finally, we discuss current challenges, including multiplexing and standardization, and outline future directions, such as the engineering of novel Cas variants and integration with smartphone technology. CRISPR-based diagnostics are poised to become indispensable tools for decentralized, efficient, and reliable GMO detection. Full article

Nanotechnology offers powerful new tools to enhance food quality monitoring and safety assurance. In the food industry, nanoscale materials (e.g., metal, metal oxide, carbon, and polymeric nanomaterials) are being integrated into sensory systems to detect spoilage, contamination, and intentional food tampering with unprecedented sensitivity. Nanosensors can rapidly identify foodborne pathogens, toxins, and chemical changes that signal spoilage, overcoming the limitations of conventional assays that are often slow, costly, or require expert operation. These advances translate into improved food safety and extended shelf-life by allowing early intervention (for example, via antimicrobial nano-coatings) to prevent spoilage. This review provides a comprehensive overview of the types of nanomaterials used in food sensory applications and their mechanisms of action. We examine current applications in detecting food spoilage indicators and adulterants, as well as recent innovations in smart packaging and continuous freshness monitoring. The advantages of nanomaterials—including heightened analytical sensitivity, specificity, and the ability to combine sensing with active preservative functions—are highlighted alongside important toxicological and regulatory considerations. Overall, nanomaterials are driving the development of smarter food packaging and sensor systems that promise safer foods, reduced waste, and empowered consumers. However, realizing this potential will require addressing safety concerns and establishing clear regulations to ensure responsible deployment of nano-enabled food sensing technologies. Representative figures of merit include Au/AgNP melamine tests with LOD 0.04–0.07 mg L⁻¹ and minute-scale readout, a smartphone Au@carbon-QD assay with LOD 3.6 nM, Fe₃O₄/DPV detection of Sudan I at 0.001 µM (linear 0.01–20 µM), and a reusable Au–Fe₃O₄ piezo-electrochemical immunosensor for aflatoxin B1 with LOD 0.07 ng mL⁻¹ (≈15 × reuse), alongside freshness labels that track TVB-N/amine in near-real time and e-nose arrays distinguishing spoilage stages. Full article

Maintaining an effective facial seal is critical for the performance of tight-fitting industrial respirators used in high-risk sectors such as mining, manufacturing, and construction. Traditional fit verification methods—Qualitative Fit Testing (QLFT) and Quantitative Fit Testing (QNFT)—are limited to periodic assessments and cannot detect fit degradation during active use. This study presents a real-time fit detection system based on embedded breath sensors and machine learning algorithms. A compact sensor module inside the respirator continuously measures pressure, temperature, and humidity, transmitting data via Bluetooth Low Energy (BLE) to a smartphone for on-device inference. This system functions as a multimodal biosensor: intra-mask pressure tracks flow-driven mechanical dynamics, while temperature and humidity capture the thermal–hygrometric signature of exhaled breath. Their cycle-synchronous patterns provide an indirect yet reliable readout of respirator–face sealing in real time. Data were collected from 20 healthy volunteers under fit and misfit conditions using OSHA-standardized procedures, generating over 10,000 labeled breathing cycles. Statistical features extracted from segmented signals were used to train Random Forest, Support Vector Machine (SVM), and XGBoost classifiers. Model development and validation were conducted using variable-size sliding windows depending on the person’s breathing cycles, k-fold cross-validation, and leave-one-subject-out (LOSO) evaluation. The best-performing models achieved F1 scores approaching or exceeding 95%. This approach enables continuous, non-invasive fit monitoring and real-time alerts during work shifts. Unlike conventional techniques, the system relies on internal physiological signals rather than external particle measurements, providing a scalable, cost-effective, and field-deployable solution to enhance occupational safety and regulatory compliance. Full article

This study introduces a novel nucleic acid testing (NAT) protocol that integrates rapid deoxyribonucleic acid (DNA) extraction, isothermal amplification, and visual detection to enable efficient analysis of opportunistic pathogens. Polyethylenimine-functionalized iron oxide (PEI-Fe₃O₄) nanoparticles were prepared by combining PEI, acting as a stabilizing agent, with iron salt, which was utilized as the metal ion precursor by the ultrasonication-assisted co-precipitation method, and characterized for structural, optical, and magnetic properties. PEI-Fe₃O₄ exhibited cationic and anionic behavior in response to pH variations, enhancing adaptability for DNA binding and release. PEI-Fe₃O₄ enabled efficient extraction of E. faecium DNA within 10 min at 40 °C, yielding 17.4 ng/µL and achieving an extraction efficiency of ~59% compared to a commercial kit (29.5 ng/µL). The extracted DNA was efficiently amplified by loop-mediated isothermal amplification (LAMP) at 65 °C for 45 min. Pyrogallol-rich poly(tannic acid)-stabilized gold nanoparticles (PTA-AuNPs) served as colorimetric probes for direct visual detection of the DNA amplified using LAMP. The magnetic-nanogold (PEI-Fe₃O₄/PTA-AuNPs) hybrid system achieved a limit of quantification of 1 fg/µL. To facilitate field deployment, smartphone-based RGB analysis enabled quantitative and equipment-free readouts. Overall, the PEI-Fe₃O₄/PTA-AuNPs hybrid system used in NAT offers a rapid, cost-effective, and portable solution for DNA detection, making the system suitable for microbial monitoring. Full article

Thanks to their low-cost, portability, and sustainability, microfluidic thread-based analytical devices (μTADs) are emerging as an attractive analytical platform for wearable biosensing. While several μTADs, mainly based on colorimetric and electrochemical detection methods, have been developed, achieving the needed sensitivity and accuracy for these biosensors continues to present a significant challenge. Prompted by this need we investigated for the first time the implementation of chemiluminescence (CL) as a detection technique for μTADs. Exploiting the lactate oxidase-catalyzed reaction coupled with the enhanced luminol/H₂O₂/horseradish peroxidase CL system, we developed a cotton-thread-based chemiluminescent device enabling the detection of lactate with a limit of detection of 0.25 mM in a 2 µL volume of artificial sweat at pH 6.5 within 3 min. The use of recycled grape skin as support made the device sustainable, while the smartphone detection allowed a simple and quantitative readout for the end-user. Using a smartphone as a detector, the analytical performance was evaluated in different conditions and in the presence of potential interferents, showing suitability for monitoring lactate levels in physiological conditions, such as for monitoring anaerobic thresholds in endurance training. Full article

The signal-processing architecture of passive surface acoustic wave (SAW) sensors presents significant implementation challenges due to its radar-like operational principle and the inherent complexity of discrete component-based hardware design. While System-in-Package (SiP) has demonstrated remarkable success in miniaturizing electronic systems for smartphones, automotive electronics, and IoT applications, its potential for revolutionizing SAW sensor interrogator design remains underexplored. This paper presents a novel architecture that synergistically combines time-domain ADC design with SiP-based miniaturization to achieve unprecedented simplification of SAW sensor readout systems. The proposed time-domain ADC incorporates an innovative delay chain calibration methodology that integrates physical unclonable function (PUF) principles during time-to-digital converter (TDC) characterization, enabling the simultaneous generation of unique system IDs. The experimental results demonstrate that the integrated security mechanism provides variable-length bit entropy for device authentication, and has a reliability of 97.56 and uniqueness of 49.43, with 53.28 uniformity, effectively addressing vulnerability concerns in distributed sensor networks. The proposed SiP is especially suitable for space-constrained IoT applications requiring robust physical-layer security. This work advances the state-of-the-art wireless sensor interfaces by demonstrating how time-domain signal processing and advanced packaging technologies can be co-optimized to address performance and security challenges in next-generation sensor systems. Full article