Fabrication of ternary MoS-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 MoS-polypyrrole (PPy)-Pd nanotubes have been prepared through a hydrothermal reaction and in situ redox polymerization process between pyrrole monomer and NaPdCl. The prepared MoS-PPy-Pd nanotubes exhibited a higher peroxidase-like catalytic activity than individual MoS, MoS-PPy, PPy-Pd and MoS-Pd nanocomposites due to the synergistic catalytic effect between the three components. The catalytic kinetic of MoS-PPy-Pd nanotubes follows Michaelis-Menten behaviors, exhibiting a good affinity to both 3,3',5,5'-tetramethylbenzidine (TMB) and HO substrates. On the basis of high peroxidase-like catalytic efficiency of the MoS-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 MoS-PPy-Pd nanotubes for promising potential applications in biosensing, environmental monitoring, and medical diagnostics.