Search Results (316)

A new sensor was developed to detect Hg²⁺ ions; different volume ratios of chloroauric acid and sodium citrate were used, which were 1.0, 0.8 and 0.5. Three kinds of gold nanoparticles (AuNPs) with sizes of 18 nm, 25 nm and 32 nm were synthesized in this way. The functional modification with succinimide and glutarimide was performed on these three sizes of AuNPs. Hg²⁺ was detected by colorimetric detection of AuNPs modified with succinimide and glutarimide. Research shows that, because a complex structure was formed by a coordination reaction with Hg²⁺, the aggregation of AuNPs occurred, the color changed from red to purple, and the characteristic absorption peak of the UV–visible absorption spectrum was redshifted. The best visual detection limit is 5 μmol/L, showing good selectivity and broad applicability; it was found that the material was specific to the detection of Hg²⁺. The novelty of this study lies in the use of simple imide-containing modifiers and the systematic comparison of particle-size-dependent colorimetric responses of modified AuNPs toward Hg²⁺. These results offer a promising approach for tracking and monitoring Hg²⁺ contamination in aquatic environments. Full article

Inorganic mercury ions (Hg²⁺) are highly toxic, posing a threat to aquatic ecosystems and human health. In this study, iron phthalocyanine (FePc) was anchored onto the surface of MXene via a self-assembly strategy to construct an FePc/MXene-x (F/M-x) heterostructure. Characterization by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption–desorption (BET) confirmed that the high specific surface area and good conductivity of MXene effectively inhibited FePc aggregation and increased the exposure of active sites. The F/M-x composite was then modified onto a glassy carbon electrode (GCE) to fabricate an electrochemical sensor, and the detection performance for Hg²⁺ was evaluated using square-wave anodic stripping voltammetry (SWASV). Under optimized conditions (pH = 5.0, accumulation at −1.2 V for 180 s), the F/M-100/GCE exhibited a linear range of 0.1–1.0 μM, a sensitivity of 19.02 μA/μM, and a detection limit of 5.9 nM. The sensor showed good anti-interference ability against coexisting metal ions such as Cd²⁺, Cu²⁺, and Pb²⁺, with a batch-to-batch RSD of 2.03% and a long-term stability RSD of 2.49%. Spike recovery experiments in real water samples (lake water and groundwater) verified the accuracy of the method. This study provides a new electrochemical platform for the rapid detection of trace Hg²⁺ in water environments. Full article

Background: High-intensity interval training (HIIT) is increasingly implemented in school-based physical education, yet little is known about how exercise intensity changes across repeated sessions and whether such trajectories are associated with physiological adaptations in adolescents. Methods: This study, conducted within the PEER-HEART project (ClinicalTrials.gov: NCT06431230), included 145 adolescents from the experimental arms of a broader school-based trial, stratified by sex and training modality: male HIPT (n = 24), male HIIT (n = 45), female HIPT (n = 46), and female HIIT (n = 30). The 8-week intervention was delivered twice weekly, and exercise intensity was monitored during 16 sessions using heart rate sensors. Intensity trajectories were examined using visual trajectory plots and slope-based statistical analyses, and pre-to-post changes in body fat percentage, systolic and diastolic blood pressure, and predicted VO₂max were analyzed. Results: Visual analyses indicated sex- and modality-specific intensity patterns, with the female HIIT group showing the most dynamic trajectory. Mean changes ranged from −0.63 ± 2.37% to −1.54 ± 2.66% for body fat, from −2.73 ± 5.28 to −5.37 ± 4.32 mmHg for systolic blood pressure, from −0.22 ± 5.00 to −2.62 ± 6.25 mmHg for diastolic blood pressure, and from 0.41 ± 3.25 to 3.81 ± 4.67 mL/kg/min for predicted VO₂max across subgroups. Although most delta values showed no significant main effects, a sex × modality interaction was observed for body fat percentage, and a main effect of sex was observed for predicted VO₂max. Greater intensity progression was associated with larger reductions in diastolic blood pressure in the female HIIT (β = −708.0, p < 0.001, R² = 0.39) and male HIIT groups (β = −377.0, p = 0.014, R² = 0.13) and with greater improvements in predicted VO₂max in the female HIPT (β = 154.0, p = 0.029, R² = 0.104) and male HIIT groups (β = 315.0, p = 0.029, R² = 0.106). Conclusions: Individual intensity trajectories may help explain variability in physiological responses to school-based interval training and may provide additional insight beyond group-level comparisons alone. Full article

Although compression therapy is widely used to improve wound healing, selecting the appropriate pressure remains a challenge in clinical practice. This work proposes an intelligent patch integrated into a bandage that allows for the simultaneous monitoring of the applied pressure and wound condition using Near-Field Communication (NFC). The proposed patch integrates a force-sensitive resistive sensor to measure pressure and a capacitive sensor to detect wound exudate through capacitance variations. Capacitance is obtained by analyzing the delay in the stepwise response of the sensor, while resistance is measured from the voltage drop across a resistive divider, which is read by a microcontroller’s analog-to-digital converter. The system is powered wirelessly through NFC energy harvesting, triggered by a mobile device that acts as a reader. The NFC module can be moved away after measurement to improve patient comfort or remain integrated into the dressing for periodic monitoring. Experimental results demonstrate pressure measurements up to 140 mmHg and exudate detection up to 200 $\mathsf{\mu }$L, confirming the feasibility of battery-free NFC smart bandages for therapeutic monitoring based on wound compression. Full article

Graphitic carbon nitride (g-C₃N₄), an emerging metal-free semiconductor material, has attracted considerable attention in the field of photoelectrochemical (PEC) sensing due to its unique electronic structure, excellent chemical stability, and visible-light responsiveness. This article systematically reviews recent advances in research on g-C₃N₄-based PEC sensors applied to water environment monitoring. First, the fundamental physicochemical properties of g-C₃N₄ are introduced, along with its advantages and limitations in PEC sensing applications. Subsequently, four main performance enhancement strategies are outlined: heterojunction construction (including type II, Z-scheme, and S-scheme heterojunction), elemental doping and defect engineering, morphology control and nanostructure design, as well as various signal amplification approaches such as self-powered systems, dual-mode detection, and cyclic amplification. Furthermore, the current application status of these sensors in detecting typical water pollutants, including heavy metal ions (e.g., Pb²⁺, Cu²⁺, Cd²⁺, Hg²⁺), antibiotics (e.g., tobramycin, norfloxacin, kanamycin), pesticide residues (e.g., chlorpyrifos, atrazine, glyphosate), and pathogenic microorganisms (e.g., Salmonella, Candida albicans), is comprehensively reviewed, with particular emphasis on detection sensitivity, selectivity, and real-sample performance. Finally, the remaining challenges in terms of long-term stability, anti-interference capabilities in complex matrices, portability, and multifunctional integration are analyzed, and future development directions are proposed, including smartphone-based intelligent sensing, CRISPR/Cas12a-assisted signal amplification, and multi-target high-throughput detection. This review aims to provide a reference for the rational design and practical application of g-C₃N₄-based PEC sensors in the field of water environment monitoring. Full article

Surface-enhanced Raman scattering (SERS) offers exceptional sensitivity for trace contaminant detection; conventional noble-metal substrates suffer from high cost, signal irreproducibility, and poor chemical stability. While semiconductor alternatives are promising, their performance is fundamentally limited by sluggish interfacial charge-transfer kinetics under static band alignment. To overcome these limitations, we introduced a new strategy centred on a high carrier generation rate (HCGR). By integrating TiOPc, a material that exhibits strong Ti–O bond polarisation and a high HCGR, with atomically thin MoS₂, we constructed a hybrid platform that drives efficient charge transfer via HCGR-enabled kinetic pumping, surpassing traditional thermodynamic band engineering. This HCGR-driven efficient CT mechanism primarily amplifies SERS through enhanced chemical mechanisms (CM) with minor electromagnetic contributions, achieving an enhancement factor (EF) of 10⁷. The platform can detect methylene blue (MB) and rhodamine 6G (R6G) at concentrations as low as 10⁻¹⁴ M and 10⁻¹³ M, respectively, demonstrating excellent repeatability (RSD = 7.2%) and stability over 60 days. Additionally, efficient CT accelerated MB photodegradation under UV light, achieving complete decomposition within 80 min. The practical applicability of the platform is evidenced by detecting Hg²⁺ (LOD: 10⁻¹¹ M) and malachite green in tap/lake water (LODs: 10⁻¹² M/10⁻¹⁰ M). This work establishes HCGR-driven efficient CT as the next generation of semiconductor SERS platforms. It provides a scalable route toward low-cost, reusable sensors for real-time, in situ monitoring of industrial effluents and the dynamic pollutant degradation of pollutants in environmental monitoring. Full article

Background/Objectives: Peripheral(-muscle) oxygenation assessed with near-infrared spectroscopy might serve as an early marker of infection/inflammation; however, evidence of its clinical relevance is lacking so far. This study aimed to develop a peripheral(-muscle) oxygenation and perfusion score (POP-Score) using the peripheral(-muscle) tissue oxygenation index (pTOI) combined with non-invasive monitoring parameters within six hours after birth. The POP-Score was designed to explore associations with elevated C-reactive protein (CRP), as an early infection/inflammation marker, in term and late-preterm neonates. Methods: Secondary outcome parameters from a prospective observational study were analysed. Included neonates weighed ≥2000 g with respiratory distress, excluding those with umbilical artery pH < 7.20. Neonates with CRP ≥ 20 mg/L were 1:4-matched to those with CRP < 20 mg/L by gestational age (±2 weeks). For pTOI measurements, a sensor was placed for a duration of 30 s, followed by four further reapplications of the sensor, using the NIRO200NX within the first six hours after birth. The POP-Score was established using the following formula: (pTOI [%] × subcutaneous fat layer thickness [cm] × heart rate [bpm])/(arterial oxygen saturation [%] × systolic blood pressure [mmHg]). POP-Score was correlated with the highest CRP within 48 h. Results: Thirty neonates were included (median gestational age: 39.1 weeks [CRP < 20 mg/L group] vs. 37.3 weeks [CRP ≥ 20 mg/L group], p = 0.299; median birth weight: 3561 g vs. 3260 g, p = 0.058, respectively). Median POP-Scores were significantly different: 1.11 (CRP ≥ 20 mg/L) vs. 0.85 (CRP < 20 mg/L), p < 0.001. POP-Score correlated positively with CRP (r = 0.341; p = 0.070). In this small exploratory cohort, a POP-Score cut-off of 1.00 was associated with CRP ≥ 20 mg/L (100% sensitivity and 87% specificity); however, these estimates are uncertain due to the limited sample size. Conclusions: This study is the first to describe a new score for peripheral(-muscle) oxygenation and perfusion (POP-Score), which may represent a potential approach for early, non-invasive assessment but requires validation in adequately powered studies before any clinical application. Trial Registration: Clinicaltrials.gov, Trial registration number: NCT04818762, Date of Registration: 26 March 2021. Full article

Mercury ion, a highly toxic and bioaccumulative heavy metal pollutant, poses significant risks to human health and ecosystems even at trace concentrations. Therefore, the development of highly sensitive and selective analytical methods for mercury ions is critically important to safeguard environmental integrity and human health. In this work, 4-mercaptopyridine-functionalized gold nanoparticles (4-MPY-AuNPs) were synthesized and subsequently immobilized onto quartz slides to fabricate a localized surface plasmon resonance (LSPR) sensor. Exploiting the selective coordination interaction between the pyridyl nitrogen atoms of 4-MPY and Hg²⁺, this LSPR sensor enables highly specific detection of Hg²⁺. Moreover, injecting a trace amount of 4-mercaptopyridine-functionalized AuNPs into the flow cell triggers the in situ formation of a surface-confined AuNP–Hg²⁺–AuNP sandwich architecture, thereby enhancing the sensor’s sensitivity. Under the optimized conditions, the proposed method exhibited a linear dynamic range of 1 × 10⁻⁹–6 × 10⁻⁷ mol L⁻¹, with a correlation coefficient (R²) of 0.9917 and a limit of detection (LOD) of 3.2 × 10⁻¹⁰ mol L⁻¹; the LOD of this method is one order of magnitude lower than the LODs reported in contemporary Hg²⁺ detection methods. This method exhibits high selectivity, sensitivity, cost-effectiveness, and is label-free, thereby demonstrating significant potential for environmental applications. Full article

In electrochemical nitrite detection, the strong oxidizing nature of nitrite often leads to high detection potentials, posing a significant challenge. To address this issue, this study successfully fabricated a nickel oxide/carbon cloth (NiO/CC) electrode using a one-step electrodeposition method followed by calcination. Taking advantage of the excellent electrocatalytic reduction properties of nickel oxide—particularly the surface oxygen vacancies that serve as active sites for efficient nitrite ion adsorption and promote the hydrogenation of the key intermediate (*NO)—the reaction energy barrier is substantially reduced. As a result, the NiO/CC electrode enables high-sensitivity nitrite detection at a low potential. Electrochemical evaluations reveal that the NiO/CC sensor performs excellently at −0.15 V (vs. Hg/HgO), featuring a linear detection range of 10–500 μM, a low detection limit of 0.091 μM (S/N = 3), and a high sensitivity of 2910 μA·mM⁻¹·cm⁻². These results highlight the promise of a catalytic reduction-based strategy for lowering detection potentials and provide a crucial foundation for the rational design of high-performance electrochemical sensing interfaces. Full article

A continued interest in developing a low-cost, rapid screening method for quantifying Hg (II) and As (III) in biological samples stems from the toxic effects of human exposure to these heavy metal ions. This study reports the use of cysteine-capped gold nanoparticles (CysAuNPs) for chemical sensing, colorimetric detection, and quantification of As (III) and Hg (II) ions in human serum albumin (HSA) under physiological conditions. Zeta potential measurements indicated that the CysAuNPs have a negative surface charge, which was decreased in the presence of HSA and reversed to a positive value upon binding of As (III) and Hg (II) metal ions. Circular dichroism (CD) spectroscopy revealed changes in HSA conformation upon binding to As (III) and Hg (II) ions. X-ray fluorescence enables rapid qualitative screening for As (III) and Hg (II) ions before colorimetric quantification. The figures of merit (R² ≥ 0.940) and the low detection limits (0.05 ppm for As (III) ions and 0.02 ppm for Hg (II)) in serum albumin demonstrate the high sensitivity of the method. The developed calibration curves correctly quantified the concentration of As (III) and Hg (II) ions of independently prepared test validation samples in HSA with an accuracy of ≥95% over a period of seven months without recalibrations, demonstrating the stability of CysAuNPs in solution and the robustness of the method for analysis of As (III) and Hg (II) ions in serum albumin. Full article

Hypertension is a major risk factor for cardiovascular disease and requires effective long-term monitoring. Photoplethysmography (PPG), acquired from wearable optical sensors, offers a convenient and non-invasive signal source for cuffless blood pressure (BP) estimation, but existing studies have mainly emphasized model architecture optimization, with limited systematic investigation of signal representation. This study systematically compares seven one-dimensional-to-two-dimensional signal transformation methods and evaluates multiple architectural variants for PPG-based cuffless BP estimation under a unified framework. Experiments were conducted using PPG and arterial BP signals from the UCI Open Blood Pressure Database. The best-performing configuration, based on continuous wavelet transform (CWT), achieved estimation errors of 3.80 ± 5.02 mmHg for systolic BP and 1.65 ± 2.70 mmHg for diastolic BP. Further real-world validation on 26 participants using an Omron cuff-based monitor as the reference showed good consistency, with correlation coefficients of R = 0.96 for SBP and R = 0.74 for DBP. The results demonstrate that appropriate signal representation, particularly CWT, plays a critical role in improving estimation accuracy and robustness, and may facilitate the development of wearable cuffless BP monitoring systems. Full article

Environmental pollution constitutes an increasingly complex global challenge, largely driven by industrial expansion and the consequent release of toxic species such as Cd²⁺, Pb²⁺, Cu²⁺, Hg²⁺, Fe³⁺, As³⁺, and Rh³⁺ into natural ecosystems. These contaminants pose significant risks to environmental integrity and public health, motivating the development of analytical technologies capable of sensitive, selective, and reliable detection. In this context, graphene-based electrochemical sensors have emerged as versatile platforms for monitoring a broad range of analytes, particularly in environmental applications involving heavy-metal detection. The intrinsic physicochemical properties of graphene derivatives have enabled low detection limits, rapid response times, and tunable selectivity. Despite analytical advances, critical challenges persist regarding operational stability in complex matrices, inter-batch reproducibility, and robustness to interfering species, which continue to hinder large-scale deployment and real-world applicability. However, challenges remain regarding stability and performance in complex arrays, reproducibility, and resistance to interference, necessitating innovative strategies for functionalization and molecular recognition. This review article establishes a comparative framework based on functionalization strategies (covalent, non-covalent, and hybrid), the chemical nature of graphene (GO, rGO, and doping), and various types of polymers (conductors and insulators), using statistical metrics such as the limit of detection (LOD), linear range, working potential, stability, and interferences, employing a bibliometric analysis using the PRISMA 2020 methodology. This comparative framework enables analysis and explanation of performance trends, and the generation of design and functionalization recommendations for versatile applications, including criteria for reproducibility and sustainability. Full article

This work presents wirelessly interrogated microelectromechanical system (MEMS) capacitive sensors for continuous intraocular pressure (IOP) monitoring. The sensor uses a passive inductor–capacitor (LC) tank circuit comprising a fixed, on-chip spiral inductor and a pressure-sensitive, variable-gap capacitor with parallel-plate membrane electrodes and side anchors. The membrane is designed with dimensions of 500 µm × 500 µm × 2 µm and a capacitive transducer gap of 2.5 µm. Applied pressure deflects the top membrane, producing a corresponding capacitance variation that changes the frequency and phase response of the LC tank circuit, enabling real-time and continuous IOP monitoring over a target detection range of 0–50 mmHg and beyond. Mutual inductive coupling between the sensor and the external readout coil is investigated as a reliable readout mechanism. Full article

Mercury ions (Hg²⁺) are highly toxic and pose severe risks to human health and ecosystems, necessitating sensitive detection methods for environmental monitoring. Here, we report a paper-based graphene sensor functionalized with single-stranded DNA (ssDNA) probes for Hg²⁺ detection based on T-Hg²⁺-T coordination chemistry. To elucidate the effect of probe structure on sensing performance, we designed DNA constructs with varying numbers of guanine (G) bases (3–6, designated DNA2–DNA5) in the bridging fragment and systematically evaluated their influence on hairpin stability, Hg²⁺ binding affinity, and sensor response. The DNA3-based sensor (four G bases) exhibited optimal electronic stability and sensitivity, achieving a detection limit of 0.673 pM with effective real-time monitoring capability in aqueous media. These findings highlight the critical role of DNA sequence design in T-Hg²⁺-T-based biosensors and provide a promising strategy for sensitive and selective Hg²⁺ detection in environmental samples. Full article

The Middle-Wave Infrared Imaging Spectrometer for Target Asteroids (MIST-A) will be launched in 2028 aboard the Emirates Mission to the Asteroid belt (EMA) and will operate in the 2–5 μm spectral range to study the asteroids’ surface composition and thermo-physical properties. MIST-A’s Optical Head (OH) design is inherited from the Jovian IR Auroral Mapper (JIRAM), from which the instrument also received two spare Hybrid-Thinned Mercury-Cadmium-Telluride (MCT) photodetectors: the Engineering Model EM2 and the Flight Spare FS1. These are tested to assess their performance after a long period of storage. The laboratory setup for testing both detectors consists of a blackbody and a cryostat which houses the focal plane, maintained at temperatures of 85 K, its nominal operative temperature, and 90 K. Two sets of measurements are performed: (1) characterization of the dark current at different integration times (0 ms, 224 ms, 448 ms, 672 ms, 869 ms, 1120 ms); (2) verification of the detectors’ response linearity, measuring a blackbody at different temperatures (from 50 °C to 100 °C), including ambient temperature (25 °C, with the blackbody turned off). The results of these tests confirm that both models are fully operational and allow us to evaluate the consequences of the years of inactivity on their performance. Through a detailed analysis of the detectors’ properties and a comparison study with the results of the sensors’ first characterization performed by their producer in 2009, we come to the conclusion that both instruments are able to fulfill MIST-A’s scientific requirements. The FS1 displays a better performance with respect to the EM2 and for this has been selected as MIST-A’s Flight Model. Full article