Colorimetric determination of D-penicillamine based on the peroxidase mimetic activity of hierarchical hollow MoS2 nanotubes

A colorimetric assay was designed for the detection of D-penicillamine (D-PA). In this work, hierarchical hollow molybdenum disulfide nanotubes (HH-MoS2) were implemented as peroxidase mimetic catalysts. The pink-colored free cation radicals were generated through oxidation of N,N-diethyl-p-phenylenediamine (DPD) by hydrogen peroxide under the catalytic activity of HH-MoS2. The main role of HH-MoS2 was the enhancement of cation radical generation, thereby, improving the sensitivity of the sensor. In the presence of D-PA, the oxidation reaction of DPD was inhibited and the absorption bands of the cation radicals (at 510 and 551 nm) diminished while a new absorption band appeared at 475 nm. Good linearity between the absorbance ratio (A551/A475) and D-PA concentration in the range of 7.0-60.0 μg mL−1 was acquired and a detection limit of 0.63 μg mL−1 was achieved. As a practical application, this colorimetric sensor was successfully used to determine the D-PA content of the pharmaceutical formulation.