Preparation of Pt anchored on cerium oxide and ordered mesoporous carbon tri-component composite for electrocatalytic oxidation of adrenaline

Oatmeal-derived carbon loaded with Pt nanoparticles using a "two-fold benefit approach" for sensitive detection of the biomolecule adrenaline

In this study, we innovatively synthesized nitrogen-doped carbon microspheres (NCS) derived from oatmeal. By utilizing polyoxometalates (POM) as both reducing and linking agents, we achieved uniform loading of platinum nanoparticles (Pt NPs) onto the surface of the NCS. The composite nanoparticles constructed from Pt/polyoxometalate/nitrogen-doped carbon microspheres (Pt/POM/NCS) fully exploit the synergistic catalytic effect, demonstrating superior performance in adrenaline detection. The method has a linear range of 2.59 to 1109.59 μM, a detection limit as low as 0.25 μM (S/N = 3), and a sensitivity of 0.74 μA μM-1 cm-2. Additionally, it exhibits high stability and strong anti-interference ability. The recoveries in human serum were 98.51 % to 101.25 %.

Facile synthesis of Pt/polyoxometalate/hollow carbon sphere tri-component nanoparticles via a "double gain strategy" for high-performance electrochemical sensing of adrenaline

In this study, we designed and successfully synthesized the Pt/polyoxometalate/hollow carbon sphere (Pt/POM/HCS) tri-component nanoparticles (NPs) by a pollution-free, efficient, and convenient method. HCSs with outstanding chemical stability and conductivity are self-generated by acid etching and calcination of silica spheres synthesized by a hard template method. HCSs have a hollow internal structure that provides specific three-dimensional storage space, and can increase the surface area. The mesoporous system is beneficial to providing numerous mass transfer passageways and immobilizing NPs. In addition, we introduced a "double gain strategy", by taking advantage of POMs as reducing and bridging agents, to achieve the loading of ultrafine Pt NPs on the surface of HCSs. Pt NPs have excellent stability and unique electrocatalytic activity. As a result of the synergistic effect of HCSs and ultrafine Pt NPs, the electrochemical sensing of adrenaline exhibits high-performance catalytic activity, sensitivity, suitable linearity range (0.16 μM-1.195 mM), and low limit of detection (57.5 nM, S/N = 3), excellent stability, and reproducibility. The developed platform is a sensitive and effective adrenaline electrical sensing platform with broad practical application prospects.

The Pt/g-C3N4-CNS catalyst via in situ synthesis process with excellent performance for methanol electrocatalytic oxidation reaction

g-C3N4-CNS prepared by the in situ synthetic method has a larger specific surface area and more anchoring sites for Pt, which promotes the dispersion of Pt and enhances the electrocatalytic performance.

'Laccase-like' properties of coral-like silver citrate micro-structures for the degradation and determination of phenolic pollutants and adrenaline

Laccases are multicopper containing oxidase enzymes that are highly important in environmental remediation and biotechnology. To date, complex Copper containing materials have been reported as laccase mimic, and the possibility of a non-Cu laccase mimic remained unknown. In this work, we report an exceptionally simple functional laccase mimic based on coral-like silver citrate (AgCit) microstructures. The AgCit was synthesized by a simple precipitation method and was found to possess excellent laccase-like activity capable of oxidizing phenolic substrates and the endocrine hormone adrenaline. Compared to the natural laccase enzyme, our reported laccase-mimic has a higher υ_max and lower K_m value using adrenaline as a substrate. In addition, the AgCit laccase mimic was observed to be stable at extreme pH, higher temperature, and suitable for long-term storage at room temperature. The laccase-like properties of the AgCit nanozyme were successfully applied for the quantification and degradation of various phenolic pollutants and the adrenaline hormone.

Epoxy-functionalized macroporous carbon with embedded platinum nanoparticles for electrochemical detection of telomerase activity via telomerase-triggered catalytic hairpin assembly

Telomerase is regarded as a crucial biomarker for the early diagnosis of malignant tumors and a valuable therapeutic target. In this work, a telomerase-triggered amplification strategy was designed on the basis of a catalyzed hairpin assembly (CHA) for bridging a signal probe of platinum nanoparticles (Pt NPs) anchored on three-dimensional (3D) epoxy-functionalized macroporous carbon (Pt/MPC-COOH) in an ultrasensitive electrochemical biosensor. Pt/MPC-COOH nanomaterials with interconnected macroporous structure not only immobilized hairpin DNA probe 2 (H2) via an amide reaction (Pt/MPC-COOH-H2), but they also generated an obvious electrochemical signal in response to acetaminophen (AP) oxidation. After the introduction of telomerase, telomerase primer (TP) was extended to a telomerase extension product (TEP) with several hexamer repeats (TTAGGG)n to initiate the CHA cycle, leading to signal amplification. Subsequently, with the TEP-triggered CHA cycle amplification strategy, a large amount of Pt/MPC-COOH-H2 was introduced on the electrode surface for the construction of the electrochemical platform, which realized the sensitive detection of telomerase activity from 10² to10⁷ cells mL^-1 with a limit of detection (LOD) of 9.02 cells mL^-1. This strategy provides a sensitive method for the detection of biomolecules that could be useful for bioanalysis and early clinical diagnoses of diseases.

Facile preparation of Ni nanoparticle embedded on mesoporous carbon nanorods for non-enzymatic glucose detection

Transition metal doped carbon materials are recognized as promising sensing platforms for glucose detection. Herein, a simple strategy involving crystallinity, nanostructure engineering, and pyrolysis was developed for constructing well-defined Ni nanoparticle embedded on nanoporous carbon nanorods (Ni/NCNs). A three-dimensional nickel-based metal-organic framework (Ni-MOF) was used as both a self-sacrificing template and precursor. Due to the synergistic effects between the uniformly dispersed Ni nanoparticles and the nanoporous carbon matrix, the as-prepared Ni/NCNs exhibited remarkable electrochemical activity. The fabricated Ni/NCNs glucose sensor showed excellent electrocatalytic performance with ultra-low limit of detection, wide linear detection ranges, fast response times (within 1.6 s), superior stability, and anti-interference characteristics. Moreover, the Ni/NCNs sensing platform was successfully applied to analyze glucose concentrations in human blood samples. These results showed that Ni/NCNs hold potential applications in developing enzyme-free glucose sensors.

An enzyme-free electrochemical biosensor based on target-catalytic hairpin assembly and Pd@UiO-66 for the ultrasensitive detection of microRNA-21

MicroRNA-21 (miR-21) has been widely investigated as important biomarkers for cancer diagnosis and treatment. Herein, a highly sensitive nonenzymatic electrochemical biosensor based on Pd@metal-organic frameworks (Pd@UiO-66) and target-catalytic hairpin assembly (CHA) with target recycling approach has been proposed for the detection of miR-21. The proposed biosensor integrates the efficient CHA strategy and excellent electrocatalytic performance of Pd@UiO-66 nanocomposites. The concentration of miRNA-21 is related to the amount of the adsorbed electrocatalyst, leading to the different electrochemical signals for readout towards paracetamol (AP). This biosensor shows a low limit of detection of 0.713 fM with the dynamic range of 20 fM -600 pM under the optimal experimental conditions, providing a powerful platform for detecting miR-21. Furthermore, the designed biochemical self-assembly strategy of this electrochemical biosensor is promising candidate for potential applications in the analysis of other important genetic biomarkers for early diagnosis of cancers.