Wearable biosensors in cardiovascular disease.

This review provides a comprehensive overview of the latest advancements in wearable biosensors, emphasizing their applications in cardiovascular disease monitoring. Initially, the key sensing signals and biomarkers crucial for cardiovascular health, such as electrocardiogram, phonocardiography, pulse wave velocity, blood pressure, and specific biomarkers, are highlighted. Following this, advanced sensing techniques for cardiovascular disease monitoring are examined, including wearable electrophysiology devices, optical fibers, electrochemical sensors, and implantable cardiac devices. The review also delves into hydrogel-based wearable electrochemical biosensors, which detect biomarkers in sweat, interstitial fluids, saliva, and tears. Further attention is given to flexible electronics-based biosensors, including resistive, capacitive, and piezoelectric force sensors, as well as resistive and pyroelectric temperature sensors, flexible biochemical sensors, and sensor arrays. Moreover, the discussion extends to polymer-based wearable sensors, focusing on innovations in contact lens, textile-type, patch-type, and tattoo-type sensors. Finally, the review addresses the challenges associated with recent wearable biosensing technologies and explores future perspectives, highlighting potential groundbreaking avenues for transforming wearable sensing devices into advanced diagnostic tools with multifunctional capabilities for cardiovascular disease monitoring and other healthcare applications.

Nanoengineered Cobalt Electrocatalyst for Alkaline Oxygen Evolution Reaction.

The alkaline oxygen evolution reaction (OER) remains a bottleneck in green hydrogen production owing to its slow reaction kinetics and low catalytic efficiencies of earth abundant electrocatalysts in the alkaline OER reaction. This study investigates the OER performance of hierarchically porous cobalt electrocatalysts synthesized using the dynamic hydrogen bubble templating (DHBT) method. Characterization studies revealed that electrocatalysts synthesized under optimized conditions using the DHBT method consisted of cobalt nanosheets, and hierarchical porosity with macropores distributed in a honeycomb network and mesopores distributed between cobalt nanosheets. Moreover, X-ray photoelectron spectroscopy studies revealed the presence of Co(OH)2 as the predominant surface cobalt species while Raman studies revealed the presence of the cubic Co3O4 phase in the synthesized electrocatalysts. The best performing electrocatalyst required only 360 mV of overpotential to initiate a current density of 10 mA cm-2, exhibited a Tafel slope of 37 mV dec-1, and stable OER activity over 24 h. The DHBT method offers a facile, low cost and rapid synthesis approach for preparation for highly efficient cobalt electrocatalysts.

Improved electrocatalytic activity of Au@Fe3O4 magnetic nanoparticles for sensitive dopamine detection.

Substantially, noble metals are important for the development of low-cost, sensitive, selective, superior performance, and portable electrochemical sensors. Herein, we describe gold (Au) nanoparticles (NPs) systematically decorated with magnetic Fe3O4 nanocomposites on the fabrication of sensitive dopamine sensor is described. Magnetic Au@Fe3O4 nanocomposites were prepared by reducing HAuCl4 on the surfaces of Fe3O4 nanoparticles. The surface morphology of Au@Fe3O4 nanocomposites was characterized by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and transmission electron microscopy (TEM). The electrochemical behaviour of the modified electrode was investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometric techniques, in which it was shown to be highly sensitive and selective towards DA. The amperometric detection of dopamine sensor, using this sensing element, exhibits a wide linear response of 0-0.8 µM with a low detection limit of 2.7 nM. In addition, the fabricated electrode showed an excellent stability and good reproducibility. The proposed analytical method was successfully applied to determine the concentration of dopamine in human urine samples and the unknown concentration of DA in human urine samples No. 1, 2 and 3 were determined as 0.056 ± 0.82 × 10-3, 0.037 ± 0.87 × 10-3 and 0.020 ± 0.94 × 10-3 µM, respectively, with recoveries ranging from 97.2% to 103.4%, suggesting that the fabricated electrode can effectively detect DA in human urine samples.

Lanthanum Thin Film on Boron-Doped Diamond, Glassy Carbon and Platinum Electrodes-An Electrochemical Approach.

Electrodeposition of lanthanum (La) thin film had been successfully carried out in the triethylmethy-lammonium methyl sulfate (TEMAMS) ionic liquid on boron-doped diamond (BDD), glassy carbon (GC) and platinum (Pt) electrodes. The electrolyte shows highest electrochemical stability window of 4.88 V on the BDD, followed by the GC (4.5 V) and Pt (4.1 V). The electrochemical reduction of La(III) ions takes place significantly at a less positive potential on the BDD than the GC, while on the Pt electrode, predominant decomposition current associated with electrochemical reduction/oxidation of TEMAMS dominates the overall process. Surface morphologic characteristics of La thin film deposits obtained on the three electrodes were characterized by scanning electron microscope (SEM) and deposited lanthanum thin film was confirmed by energy-dispersive X-ray spectroscopy (EDS) analysis.

Ag x Cu y Ni z Trimetallic Alloy Catalysts for the Electrocatalytic Reduction of Benzyl Bromide in the Presence of Carbon Dioxide.

Different compositions of trimetallic alloy containing silver, copper, and nickel (Ag x Cu y Ni z ) were electrodecorated in a protic ionic liquid medium on glassy carbon electrodes in order to investigate the suitability of the materials as catalysts for electrochemical reduction of carbon dioxide (CO2). Surface characteristic morphology obtained by scanning electron microscopy shows cauliflower crystallites for the deposit of Ag, whereas materials of Cu and Ni exhibit cubic grains and fine particles, respectively. Deposits of trimetallic alloy containing Ag, Cu, and Ni exhibit the mixture of the three characteristic features. Further, trimetallic alloy containing a large amount of Ag provides high crystallinity, whereas predominance of Cu as well as Ni results in porous structures, as revealed by X-ray diffraction analysis. Atomic absorption spectroscopy () was used to determine the compositions of different alloy materials. The suitability of nanomaterials as cathodes for electroreduction of benzyl bromide in CO2 containing 0.1 M tetra-n-butylammonium tetrafluoroborate (DMF/TBABF4)/N,N-dimethylformamide medium was explored. The linear sweep voltammogram reveals that Ag46Cu40Ni14 shows higher cathodic peak current and lower cathodic peak potential than those of other deposited nanomaterials as well as alloys, indicating its higher catalytic activity for such an electroreduction process, whereas potentiostatic electrolysis confirms the abovementioned results.

High Rate Performing in Situ Nitrogen Enriched Spherical Carbon Particles for Li/Na-Ion Cells.

Nitrogen rich, porous spherical carbon particle with the large surface area was synthesized by simple pyrolysis of the amorphous covalent organic framework. The obtained mesoporous spherical carbon particles with dilated interlayer distance (0.377 nm), large surface area (390 m2 g-1) and high level nitrogen doping (10.9%) offer eminent electrochemical performance as an anode for both lithium ion (LIBs) and sodium ion batteries (SIBs). In LIB applications, the synthesized material delivers an average reversible capacity of 820 mAh g-1 after 100 cycles at 0.1 A g-1, superior rate capability of 410 and 305 mAh g-1 at 4.0 and 8.0 A g-1 respectively. In SIBs, the material shows the stable reversible capacity of about 238 mAh g-1 for the studied 500 cycles at 0.5 A g-1. The rate and steady state cycling performance at high current densities are impressive, being as high as 165 mAh g-1 even after 250 cycles at 2.0 A g-1.