Samy M. Shaban

Hydrovoltaic energy harvesters provide a passive strategy for converting ambient moisture into electricity. However, their electrical output often rapidly decays after the removal of humidity stimulation, limiting their operation under dynamic environmental conditions. Here, we report a polyurethane‐derived polymer hydrovoltaic energy harvester (pp‐HEH) based on a hygroscopic polymeric deep eutectic solvent (HyPU _DES ). The ionic and polar sites within HyPU _DES enable rapid moisture adsorption, while the coupled interactions within the polymer network regulate subsequent moisture redistribution and release. This kinetic asymmetry between rapid moisture uptake and slow post‐stimulus water redistribution enables sustained hydrovoltaic output beyond the period of external humidity exposure. At 90% RH, the pp‐HEH delivers an open‐circuit voltage of 487 mV and a current density of 1.62 µA cm ⁻² . After 30 min exposure to 90% RH, the device maintains a voltage response for more than 120 min under 20 ± 5% RH after humidity withdrawal. This work demonstrates a material‐level strategy for extending hydrovoltaic response windows by regulating moisture transport kinetics, providing potential opportunities for self‐powered wearable and distributed electronic systems.

This study highlights hydrophobic tail engineering in gemini surfactants as an effective molecular strategy to regulate the synthesis, colloidal stability, and catalytic characteristic of AgNPs. Three hydrophobic gemini surfactants with systematically varied alkyl chain lengths of 8 carbons (GSO), 12 carbons (GSD), and 16 carbons (GSH) were employed to direct AgNP nucleation and growth. Increasing hydrophobic tail length significantly enhanced micellization behavior, surface adsorption, and coordination with Ag+ ions, thereby enabling precise control over nanoparticle size, dispersion, and surface charge. Among the investigated systems, GSH provided a uniformly dispersed AgNPs with diameter of 12.7 ± 3.9 nm and a high positive zeta potential (+25.6 ± 6.6 mV). To address nanoparticle recovery and reuse challenges, a reusable catalytic membrane was fabricated via in-situ photochemical synthesis AgNPs on sponge scaffold. The resulting sponge@AgNPs membrane was integrated into a flow-through catalytic column for efficient of methylene blue reduction to leucomethylene blue over 15 consecutive cycles. In addition, AgNPs stabilized with GSD exhibited strong antimicrobial activity, outperforming several benchmark agents. Overall, this work establishes a facile, scalable, and environmentally benign strategy that combines surfactant molecular design with column engineering, demonstrating versatile chances for sustainable catalysis and water purification applications.

Melanoma, the most lethal form of skin cancer, is closely associated with tyrosinase activity, making it a critical biomarker for early diagnosis. In this study, we developed a dual-mode biosensing platform integrating multicolorimetric and ratiometric fluorometric detection for ultra-sensitive tyrosinase quantification. This platform leverages localized surface plasmon resonance (LSPR) modulation of gold nanobipyramids (AuNBPs) alongside a fluorescence resonance energy transfer (FRET)-based mechanism using upconversion nanoparticles (UCNPs). The tunable LSPR of AuNBPs provided a bidirectional ratiometric multicolor emission improving sensitivity and selectivity. Tyrosinase-mediated oxidation of catechol to quinone inhibits silver (Ag) deposition on AuNBPs, inducing a distinct concentration-dependent color shift for precise visual quantification. This dual-modality assay achieves an exceptional limit of detection (LOD) of 4.13 × 10 ^–5 and 2.71 × 10 ^–5 U/mL for colorimetric and fluorometric sensors, respectively, demonstrating high selectivity, robustness in complex biological samples. Additionally, the assay proved effective in screening tyrosinase inhibitors, using kojic acid as a model, and achieved an IC ₅₀ value of 61.45 µM, validating its inhibition efficiency.

Ensuring food quality and safety is crucial, as the consumption of contaminated or substandard food poses serious risks to public health and imposes a substantial economic burden. Among various food safety concerns, milk adulteration with urea has emerged as a significant issue. This study presents a highly sensitive dual-mode colorimetric and fluorometric urea sensor for milk adulteration detection, utilizing enzymatic hydrolysis with Fenton-mediated plasmonic etching. The urease-catalyzed hydrolysis of urea produces ammonia, which inhibits the Fenton reaction, thereby modulating the localized surface plasmon resonance (LSPR) of gold nanobipyramids (AuNBPs). The resulting LSPR shift (Δλ > 150 nm) generates a distinct colorimetric response across a broad urea concentration range (0-5 mM), with a low limit of detection (LoD) of 0.09 μM. Moreover, the tunable LSPR of AuNBPs serves as a dynamic quencher for upconversion nanoparticles (UCNPs) via Förster resonance energy transfer (FRET), enabling ratiometric fluorometric sensing with high sensitivity (LoD of 0.056 μM). The spectral overlap between the LSPR of AuNBPs and the green/red emission of UCNPs facilitates a dynamic "Off/On-On/Off" response, ensuring accurate urea quantification in fluorescence mode. Furthermore, a smartphone-based RGB analysis enhances accessibility for on-site monitoring of urea levels, making this sensor a promising tool for real-world applications.

This study presents an innovative urea detection method utilizing pH-controlled Fenton etching of gold nanobipyramids (AuNBPs), offering a multicolor visual response. By leveraging the urease-catalyzed hydrolysis of urea, which releases ammonia and raises pH, the Fenton reaction is inhibited, reducing the etching of AuNBPs. This approach enables a highly sensitive and distinct multichromatic response across a wide range of urea concentrations, particularly at low target levels. The solution-based sensor achieved an exceptionally low detection limit of 0.098 μM, surpassing existing colorimetric urea biosensors. Furthermore, embedding the sensor in an agarose hydrogel matrix to create a solid-state format resulted in a detection limit of 0.2 μM. Real-world validation demonstrated high recovery rates in urine samples, further affirming the sensor’s reliability. This multicolor biosensing platform offers a robust tool for point-of-care diagnostics, facilitating accurate and user-friendly urea detection.

Bimetallic nanoparticles (BMNPs) combine the desirable properties of two distinct metals that outperform conventional monometallic nanoparticles (NPs). This work presents a novel ecofriendly silver‐copper (Ag–Cu) BMNPs synthesis using sunlight as a green reducing agent, enableing rapid Ag–Cu BMNPs formation at room temperature within 10 min. This method exploiting the facile reduction of Ag⁺ to Ag⁰, which subsequently mediates the reduction of Cu ² ⁺ to Cu⁰ via water radiolysis‐generated species. The Ag–Cu BMNPs were integrated into two reusable catalytic membranes: PTFE@Ag–Cu, formed by immobilizing Ag–Cu BMNPs onto a polytetrafluoroethylene (PTFE) syringe filter, and ACF@Ag–Cu, synthesized via in‐situ growth of Ag–Cu BMNPs on activated carbon fiber (ACF) cloth. PTFE@Ag–Cu displays exceptional performance and reusability, converting 2100 mL of 0.15 mM p ‐nitrophenol to p ‐aminophenol over 105 cycles at a flow rate of 20 mL min ⁻¹ . The Ag–Cu BMNPs also exhibit peroxidase‐mimic activity, enabling colorimetric H ₂ O ₂ detection with a range of 0–200 mM and a limit of detection (LOD) of 13.3 µM in solution. Further, the Ag–Cu nanoenzyme demonstrates strong potential for electrochemical glucose detection, achieving an LOD of 0.1 µM and sensitivity of 5221 µA × 10 ⁻⁶ m ⁻ ¹ cm⁻ ² .

Blood lactate concentration is an established circulating biomarker for measuring muscle acidity and can be evaluated for monitoring endurance, training routines, or athletic performance. Sweat is an alternative biofluid that may serve similar purposes and offers the advantage of noninvasive collection and continuous monitoring. The relationship between blood lactate and dynamic sweat biochemistry for wearable engineering applications in physiological fitness remains poorly defined. Here, we developed a microfluidic wearable band with an integrated colorimetric timer and biochemical assays that temporally captures sweat and measures pH and lactate concentration. A colorimetric silver nanoplasmonic assay was used to measure the concentration of lactate, and dye-conjugated SiO ₂ nanoparticle–agarose composite materials supported dynamic pH analysis. We evaluated these sweat biomarkers in relation to blood lactate in human participant studies during cycling exercise of varying intensity. Iontophoresis-generated sweat pH from regions of actively working muscles decreased with increasing heart rate during exercise and was negatively correlated with blood lactate concentration. In contrast, sweat pH from nonworking muscles did not correlate with blood lactate concentration. Changes in sweat pH and blood lactate were observed in participants who did not regularly exercise but not in individuals who regularly exercised, suggesting a relationship to physical fitness and supporting further development for noninvasive, biochemical fitness evaluations.