Electrodeposition of polypyrrole/functionalized-multiwalled carbon nanotubes composite and its application in supercapacitors

Development of a mesoporous polypyrrole nanofiber mat for simultaneous detection of multiple mycotoxins in various foods

Due to health hazards and co-contamination of mycotoxins, efficient separation and detection of multiple mycotoxins in food is highly desirable yet challenging. In this study, we prepared a novel mesoporous polypyrrole nanofiber mat (M-PPy NFM) for extracting multiple mycotoxins from food. The mesoporous effects and multifunctional PPy contribute to higher recovery and purification efficiency of M-PPy NFM for mycotoxins by facilitating hydrogen bonding and π-π interaction. Under optimized conditions, a simple, eco-friendly solid phase extraction (SPE) method coupled with high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) was developed for mycotoxin detection. This innovative method demonstrates good linearity (0.9991-0.9999), low detection limits (0.03-0.33 μg kg-1), satisfactory recoveries (92.0 %-108.0 %) and precision (0.3 %-11.7 %). Notably, it significantly reduces organic solvent consumption to 3.1 mL while minimizing adsorbent usage to 5.0 mg. Moreover, M-PPy NFM could be reused ten times. This study confirms the huge potential of M-PPy NFM for efficient applications in mycotoxin extraction and determination.

Synthesis of NiMn2O4/PANI nanosized composite with increased specific capacitance for energy storage applications

Polyaniline (PANI) stands out as a highly promising conducting polymer with potential for advanced utilization in high-performance pseudocapacitors. Therefore, there exists a pressing need to bolster the structural durability of PANI, achievable by developing composite materials that can enhance its viability for supercapacitor applications. In this particular study, a pioneering approach was undertaken to produce a novel NiMn2O4/PANI supercapacitor electrode material. A comprehensive array of analytical techniques was employed to ascertain the structural configuration, morphology, oxidation states of elements, composition, and surface characteristics of the electrode material. The electrochemical evaluation of the NiMn2O4/PANI composite shows a specific capacitance (Cs) of 1530 ± 2 F g-1 at 1 A g-1. Significantly, the composite material displays an outstanding 93.61% retention of its capacity after an extensive 10 000 cycles, signifying remarkable cycling stability, while the 2-electrode configuration reveals a Cs value of 764 F g-1 at 5 mV s-1 and 826 F g-1 at 1 A g-1 with a smaller charge transfer resistance (Rct) value of 0.67 Ω. Chronoamperometric tests showed excellent stability of the fabricated material up to 50 h. This significant advancement bears immense promise for its potential implementation in high-efficiency energy storage systems and heralds a new phase in the development of supercapacitor technology with improved stability and performance metrics.

Electrochemical detection of Salmonella using an invA genosensor on polypyrrole-reduced graphene oxide modified glassy carbon electrode and AuNPs-horseradish peroxidase-streptavidin as nanotag

A rapid and sensitive electrochemical biosensor was constructed to detect Salmonella using invA gene biosensor. The biosensing was based on polyrrole-reduced graphene oxide (PPy-rGO) nanocomposite modified glassy carbon electrode (GCE) and signal amplification with horseradish peroxidase-streptavidin biofunctionalized gold nanoparticles (AuNPs-HRP-SA). PPy-rGO was prepared at 60 °C by chemical reduction of PPy-functionalized graphene oxide (PPy-GO) that was synthesized by in situ polymerization at room temperature. The detection signal was amplified via enzymatic reduction of H₂O₂ in the presence of hydroquinone (HQ) using AuNPs-HRP-SA as nanotag. Under optimal conditions, the differential pulse voltametric (DPV) signal from the biosensor was linearly related to the logarithm of target invA gene concentrations from 1.0 × 10^-16 to 1.0 × 10^-10 M, and the limit of detection (LOD) was 4.7 × 10^-17 M. The biosensor can also detect Salmonella in the range of 9.6 to 9.6 × 10⁴ CFU mL^-1, with LOD of 8.07 CFU mL^-1. The biosensor showed good regeneration ability, acceptable selectivity, repeatability and stability, which bode well as an alternative method for Salmonella screening.