General and fast synthesis of graphene frameworks using sugars for high-performance hydrogen peroxide nonenzymatic electrochemical sensor

Bimetallic FeCo phosphide-enabled electrochemical sensor for rapid tanshinol quantification in Salvia miltiorrhiza herb at near-neutral condition

Tanshinol, an active ingredient extracted from the Salvia miltiorrhiza herb, is widely used in Chinese medicine or health supplements. Accurately and rapidly quantifying of tanshinol under near-neutral or neutral conditions is of great significance but still a significant challenge. Herein, a novel electrochemical sensor based on bimetallic FeCo phosphides (FexCo1-xP) was developed for rapid and sensitive detection of tanshinol in near-neutral environments. FexCo1-xP nanocrystals supported on porous graphene (FexCo1-xP/GFs) were synthesized, with Fe0.25Co0.75P/GFs demonstrating an enhanced electrochemical response for tanshinol detection at pH 6.5. The Fe0.25Co0.75P/GFs-based tanshinol electrochemical sensor exhibited linear detection ranges of 0.20-11.65 μM and 11.65-39.98 μM, which could accurately quantify tanshinol in Salvia miltiorrhiza herb. This study highlights the potential of earth-abundant FeCo phosphides for the electrochemical detection of tanshinol under benign conditions, offering a promising approach for the standardized analysis of Salvia miltiorrhiza herb.

Single-atom ruthenium nanozyme-induced signal amplification strategy in photoelectrochemical aptasensor for ultrasensitive detection of chloramphenicol

To develop ultrasensitive and rapid antibiotics residue detection method is crucial for ensuring food safety and protecting human health. Herein, a novel photoelectrochemical (PEC) aptasensor integrated with single-atom ruthenium (Ru) nanozyme-mediated catalytic precipitation as a valuable signal amplification strategy, have been established for ultrasensitive chloramphenicol (CAP) detection. Particularly, the exceptional peroxidase-mimicking activity of single-atom Ru nanozyme is responsible for accelerating the oxidation of 4-chloro-1-naphthol (4-CN) to produce insoluble precipitate on the electrode, which in turn causes a notable reduction in the photocurrent. Whereas, when CAP is present, the aptamer is liberated away the electrode because of its potent affinity with CAP, resulting in an elevation of the photocurrent signal, enhancing the detection sensitivity. Importantly, the signal amplification strategy combines the effective photoactive material of Au nanoparticles/CdS quantum dot/TiO2 composites, a PEC aptasensor for determination of CAP with an ultralow detection limit of 4.12 pM is achieved in a self-powered mode with great selectivity and accuracy. This work proposes a novel reasonable approach utilizing high-activity single-atom nanozyme to induce signal amplification strategy for the advancement of single-atom nanozyme in ultrasensitive PEC biosensor, and further creates new avenues for ultrasensitive detection beyond antibiotics residue.

The Roadmap of Graphene-Based Sensors: Electrochemical Methods for Bioanalytical Applications

Graphene (GR) has engrossed immense research attention as an emerging carbon material owing to its enthralling electrochemical (EC) and physical properties. Herein, we debate the role of GR-based nanomaterials (NMs) in refining EC sensing performance toward bioanalytes detection. Following the introduction, we briefly discuss the GR fabrication, properties, application as electrode materials, the principle of EC sensing system, and the importance of bioanalytes detection in early disease diagnosis. Along with the brief description of GR-derivatives, simulation, and doping, classification of GR-based EC sensors such as cancer biomarkers, neurotransmitters, DNA sensors, immunosensors, and various other bioanalytes detection is provided. The working mechanism of topical GR-based EC sensors, advantages, and real-time analysis of these along with details of analytical merit of figures for EC sensors are discussed. Last, we have concluded the review by providing some suggestions to overcome the existing downsides of GR-based sensors and future outlook. The advancement of electrochemistry, nanotechnology, and point-of-care (POC) devices could offer the next generation of precise, sensitive, and reliable EC sensors.

Graphene frameworks-confined synthesis of 2D-layered NiCoP for the electrochemical sensing of H2O2 at lower overpotential

A new 2D-layered nickel cobalt phosphide nanosheet confined by 3D graphene frameworks (denoted as NiCoP/GFs) is in situ controllably synthesized as a highly efficient and durable electrocatalyst, which is obtained from the transformation of corresponding NiCo layer double hydroxides and GFs. Hydrogen peroxide (H₂O₂) is selected as a demonstration to study the electrochemical sensing performance of the NiCoP/GFs. Benefiting from 2D morphology of NiCoP and network structure of GFs, NiCoP/GFs exhibits remarkable electroactivity toward H₂O₂ at a relatively low overpotential of approximately - 0.3 V (vs sat. Ag/AgCl) in 0.01 M phosphate-buffered saline solution (PBS, pH = 7.4). The NiCoP/GFs-based H₂O₂ electrochemical sensor achieves a high sensitivity of ∼4398 μA mM^-1 cm^-2, a low detection limit of 0.028 ± 0.006 μM, and desirable selectivity. In addition, the sensor can sensitively detect H₂O₂ from living cancer cells. This study not merely broadens the synthesis methods of transition metal phosphide-based nanocrystals but the NiCoP/GFs also has broad prospects in diverse electrochemistry fields. We have reported a controllable synthesis of 2D nickel cobalt phosphide nanosheet confined by graphene frameworks (denoted as NiCoP/GFs) as a greatly efficient and durable electrocatalyst. The NiCoP/GFs exhibits remarkable electroactivity toward detection of H₂O₂ at a relatively low overpotential of approximately -0.3 V. Density functional theory (DFT) calculations further prove that regulation of the electronic structure of NiCoP by GFs lowers the adsorption free energy of *OOH intermediates, and thus contributes to the greatly improved the electrocatalytic performance of NiCoP/GFs toward H₂O₂ reduction. The developed NiCoP/GFs can be applied as excellent electrode materials for efficient electrochemical sensing of H₂O₂.

Recent progress in the development of porous carbon-based electrodes for sensing applications

Electrochemical (bio)sensors are considered clean and powerful analytical tools capable of converting an electrochemical reaction between analytes and electrodes into a quantitative signal. They are an important part of our daily lives integrated in various fields such as healthcare, food and environmental monitoring. Several strategies including the incorporation of porous carbon materials in its configuration have been applied to improve their sensitivity and selectivity in the last decade. The porosity, surface area, graphitic structure as well as chemical composition of materials greatly influence the electrochemical performance of the sensors. In this review, activated carbons, ordered mesoporous carbons, graphene-based materials, and MOF-derived carbons, which are used to date as crucial elements of electrochemical devices, are described, starting from their textural and chemical compositions to their role in the outcome of electrochemical sensors. Several relevant and meaningful examples about material synthesis, sensor fabrication and applications are illustrated and described. The closer perspectives of these fascinating materials forecast a promising future for the electrochemical sensing field.