Manufacturing high-density graphene edges with electrochemical etching for sensing aminophenol

Laser-induced graphene/gold nanoparticle hybrid sensor for enhanced electrochemical detection of paracetamol

This research presents a highly sensitive and selective electrochemical sensor for detecting paracetamol. The sensor is created using laser direct-writing on a flexible PI substrate to form LIG electrodes. Gold nanoparticles (AuNPs) are then synthesized on the working electrode through secondary laser reduction, resulting in an AuNPs/LIG composite. This combination enhances the sensor's electrochemical activity, electron transfer rate, and adsorption capacity. The sensor exhibits a linear response to paracetamol concentrations with a detection limit of 0.086 μM. Testing on Tylenol tablets and tap water showed good recovery rates. The sensor displays strong anti-interference, reproducibility, and stability, making it a promising tool for effective paracetamol monitoring in real-world situations.

2D/3D hierarchical porous structure of mNPC/SMOH@C to construct an electrochemical sensor for the simultaneous determination of p-acetylaminophenol and p-aminophenol

BACKGROUND

As persistent organic pollutants (POPs), the accumulation of p-acetylaminophenol (PAT) and p-aminophenol (PAP) in water can seriously damage the health of plants and animals, ultimately leading to threats to human health and safety. Electrochemical sensors have the advantages of being fast, inexpensive, and accurate compared to the complex, expensive, and cumbersome conventional analytical methods. In this study, we designed and synthesized composites with two-dimensional/three-dimensional (2D/3D) porous structures to construct an efficient electrochemical platform for the simultaneous detection of PAT and PAP.

RESULTS

In this work, a novel 3D foamy birnessite Na0.55Mn2O4·1.5H2O@C (SMOH@C) was synthesized, which was composited with 2D ordered mesoporous nanosheets (mNPC) to construct electrochemical sensors detecting PAT and PAP simultaneously. The prepared 2D/3D porous structure of mNPC/SMOH@C increased the exposure of active sites due to its large specific surface area. The introduction of a 3D carbon skeleton altered the charge transfer rate of SMOH@C, and the rich pore structure and oxygen-rich vacancies created favorable conditions for the diffusion and adsorption of PAP and PAT, which enabled the sensitive detection of PAT and PAP. The constructed mNPC/SMOH@C electrochemical sensor could simultaneously detect PAT (1 × 10-7 - 1 × 10-4 M) and PAP (5 × 10-8 - 1 × 10-4 M) with detection limits of 20.4 nM and 30.1 nM, respectively. The sensor has good repeatability (RSD <4 %) and reproducibility (RSD <4 %), and satisfactory recoveries (96.7-102.8 %) were obtained in the analysis of natural water samples.

SIGNIFICANCE

In this paper, for the first time, we present the synthesis of 3D foam birnessite and its composite with mNPC for the electrochemical simultaneous detection of PAT and PAP. Our proposed strategy for fabricating 2D/3D porous composites lays the foundation for the design and synthesis of other porous materials. In addition, this study provides new ideas for developing efficient and practical electrochemical sensors for detecting pollutants in aquatic environments.

A novel biosensing strategy on the dynamic and on-site detection of Vibrio coralliilyticus eDNA for coral health warnings

Heat stress and coral diseases are the predominant factors causing the degradation of coral reef ecosystems. Over recent years, Vibrio coralliilyticus was identified as a temperature-dependent pathogen causing tissue lysis in Pocillopora damicornis and one of the primary pathogens causing bleaching and mortality in other corals. Yet current detection techniques for V. coralliilyticus rely primarily on qPCR and ddPCR, which cannot meet the requirements for non-invasive and real-time detection. Herein, we developed an effective electrochemical biosensor modified by an Au-MoS2/rGO (AMG) nanocomposites and a specific capture probe to dynamically detect V. coralliilyticus environment DNA (eDNA) in aquarium experiments, with a lower limit of detection (0.28 fM) for synthetic DNA and a lower limit of quantification (9.8 fg/µL, ∼0.86 copies/µL) for genomic DNA. Its reliability and accuracy were verified by comparison with the ddPCR method (P > 0.05). Notably, coral tissue started to lyse at only 29 °C when the concentration of V. coralliilyticus increased abruptly to 880 copies/µL, indicating the biosensor could reflect the types of pathogen and health risks of corals under heat stress. Overall, the novel and reliable electrochemical biosensing technology provides an efficient strategy for the on-site monitoring and early warning of coral health in the context of global warming.

Spindle-shaped Cu-Ru mesoporous nanospheres with enhanced enzyme-like activity for visual differentiation of toxic o-/m-aminophenol and recognition mechanisms

To effectively differentiate toxic aminophenol isomers, a kind of spindle-shaped Cu-Ru bimetal mesoporous nanozyme (Cu-Ru MPNZ) with high specific surface was developed by one-pot homogeneous reduction method, directed by hexadecyl trimethyl ammonium bromide (CTAB) in this work. By virtue of the distinctive microstructure, Cu-Ru MPNZ expressed superior bi-functional oxidase- and peroxidase-mimic activity to catalyze the oxidation of 3,3',5,5,'-tetramethylbenzidine (TMB) and 2,2'-azinobis (3-ethylbenzothiazoline-6- sulfonic acid) ammonium salt (ABTS) with low Michaelis-Menten constants and quick reaction rates. Especially, toxic aminophenol isomers could exclusively react with the oxydates of TMB or ABTS to express differentiable signals in color. Under the optimal conditions, Cu-Ru MPNZ was successfully applied for visual differentiation of toxic aminophenol isomers in real aqueous, juices and medicinal samples with low detection limits (1.60 × 10-8 mol/L for o-aminophenol and 3.25 × 10-8 mol/L for m-aminophenol) and satisfactory recoveries (96.6-103.5%). The different recognition mechanisms of Cu-Ru MPNZ to toxic o- and m-aminophenol isomers were proposed for the first time as far as we known. This work will provide a potential way to monitor different organic isomer pollution in future.

Ultrathin Graphdiyne/Graphene Heterostructure as a Robust Electrochemical Sensing Platform

Graphdiyne (GDY) has been considered as an appealing electrode material for electrochemical sensing because of its alkyne-rich structure and high degrees of π-conjugation, which shows great affinity to heavy metal ions and pollutant molecules via d-π and π-π interactions. However, the low surface area and poor conductivity of bulk GDY limit its electrochemical performance. Herein, a two-dimensional ultrathin GDY/graphene (GDY/G) nanostructure was synthesized and used as an electrode material for electrochemical sensing. Graphene plays the role of an epitaxy template for few-layered GDY growth and conductive layers. The formed few-layered GDY with a high surface area possesses abundant affinity sites toward heavy metal ions (Cd²⁺, Pb²⁺) and toxic molecules, for example, nitrobenzene and 4-nitrophenol, via d-π and π-π interactions, respectively. Moreover, hemin as a key part of the enzyme catalytic motif was immobilized on GDY/G via π-π interactions. The artificial enzyme mimic hemin/GDY/G-modified electrode exhibited promising ascorbic acid and uric acid detection performance with excellent sensitivity and selectivity, a good linear range, and reproducibility. More importantly, real sample detection and the feasibility of this electrochemical sensor as a wearable biosensor were demonstrated.