Strongly coupled CeO2/Co3O4/poly(3,4-ethylenedioxythiophene) nanofibers with enhanced nanozyme activity for highly sensitive colorimetric detection.

In this work, we have prepared CeO2/Co3O4 composite nanofibers via an electrospinning technique followed by a calcination process. Then core-shell structured CeO2/Co3O4/poly(3,4-ethylenedioxythiophene) (PEDOT) composite nanofibers were fabricated through a redox reaction between the 3,4-ethylenedioxythiophene (EDOT) monomer and Co3O4 on the surface of CeO2/Co3O4 composite nanofibers. The morphology and composition of the two composite nanofibers were confirmed by field-emission scanning electron microscopy, transmission electron microscopy, x-ray diffraction, Fourier transform infrared spectroscopy, and x-ray photoelectron spectra measurements. Due to the synergistic effect between CeO2 and Co3O4, the catalytic activity was enhanced compared to that of independent oxide nanofibers. After the growth of PEDOT, the catalytic activity process was further improved, having achieved a secondary synergistic effect. Application of the two prepared composite nanofibers as peroxidase-like catalysts for the colorimetric detection of H2O2 was investigated. It is anticipated that this work can inspire researchers to develop various novel functional nanocomposites for applications in biosensing and environmental monitoring.

Self-templated fabrication of FeMnO3 nanoparticle-filled polypyrrole nanotubes for peroxidase mimicking with a synergistic effect and their sensitive colorimetric detection of glutathione.

A self-templated approach has been developed for the preparation of FeMnO3 nanoparticles filled in the hollow core of polypyrrole (PPy) nanotubes by an in situ polymerization process accompanied by the etching of FeMnO3 nanofibers. The prepared FeMnO3@PPy nanotubes exhibited a superior peroxidase-like activity. The catalytic reaction system has been used for the sensitive colorimetric detection of glutathione with a low detection limit and good selectivity.

Fabrication of ternary MoS2-polypyrrole-Pd nanotubes as peroxidase mimics with a synergistic effect and their sensitive colorimetric detection of l-cysteine.

Over the past few years, nanomaterials-based enzymatic mimics have attracted tremendous attention due to their excellent catalytic activity and environmental stability. In this work, ternary MoS2-polypyrrole (PPy)-Pd nanotubes have been prepared through a hydrothermal reaction and in situ redox polymerization process between pyrrole monomer and Na2PdCl4. The prepared MoS2-PPy-Pd nanotubes exhibited a higher peroxidase-like catalytic activity than individual MoS2, MoS2-PPy, PPy-Pd and MoS2-Pd nanocomposites due to the synergistic catalytic effect between the three components. The catalytic kinetic of MoS2-PPy-Pd nanotubes follows Michaelis-Menten behaviors, exhibiting a good affinity to both 3,3',5,5'-tetramethylbenzidine (TMB) and H2O2 substrates. On the basis of high peroxidase-like catalytic efficiency of the MoS2-PPy-Pd nanotubes, a simple and convenient colorimetric strategy for the rapid and sensitive detection of l-cysteine with a detection limit of 0.08 µM has been developed. In addition, a high selectivity towards the detection of l-cysteine is achieved. This work present an opportunity of the prepared ternary MoS2-PPy-Pd nanotubes for promising potential applications in biosensing, environmental monitoring, and medical diagnostics.

Self-Assembly Fabrication of Coaxial Te@poly(3,4-ethylenedioxythiophene) Nanocables and Their Conversion to Pd@poly(3,4-ethylenedioxythiophene) Nanocables with a High Peroxidase-like Activity.

Here, we report a simple one-step procedure to fabricate coaxial Te@poly(3,4-ethylenedioxythiophene) (PEDOT) nanocables via a self-assembly redox polymerization between 3,4-ethylenedioxythiophene monomer and the oxidant of sodium tellurite without the assistance of any templates and surfactants. The as-synthesized Te@PEDOT coaxial nanocables have diameters of center cores in the range of 5-10 nm, and the size of the outer shell from several nanometers to 15 nm. More interestingly, the as-prepared Te@PEDOT nanocables can be converted to Pd@PEDOT nanocables via a galvanic replacement reaction. The center core of the Pd nanowire exhibits a high crystallinity. The application of the synthesized Pd@PEDOT nanocables as peroxidase-like catalysts for the colorimetric detection of H2O2 is reported. The synergistic effect between the Pd nanowire and electrically conducting PEDOT enhances the catalytic activity toward the oxidation of the peroxidase substrate 3,3',5,5'-tetramethylbenzidine in the presence of H2O2. A detection limit toward H2O2 is as low as 4.83 µM, and a linear range from 10 to 100 µM has been achieved. This work offers a potential versatile route for the fabrication of cable-like nanocomposites with conducting polymers and other active components, which display great promise in applications such as catalysis, nanoelectronic devices, and energy storage and conversion.

Electroactive self-doped poly(amic acid) with oligoaniline and sulfonic acid groups: synthesis and electrochemical properties.

A novel poly(amic acid) with pendant aniline tetramer and sulfonic acid groups (ESPAA) was synthesized by ternary polymerization and characterized by Fourier-transform infrared spectra, ((1))H NMR and gel permeation chromatography. The polymer showed good thermal stability and excellent solubility in the common organic solvents. The electrochemical properties were investigated carefully on a CHI 660A Electrochemical Workstation. The polymer displayed good electroactivity in acid, neutral and even in alkaline solutions (pH=1-10) due to the self-doping effect between aniline tetramer and sulfonic/carboxylic acid groups. It also exhibited satisfactory electrochromic performance with high contrast value, acceptable coloration efficiency and fast switching time in the range of pH=1-9.