Accelerated Mimetic Oxidase Activity of Polydopamine-Dressed PdCu Nanozyme for the Detection of Ascorbic Acid Related Bioenzymes
Chenghui Zhang, Wendong Liu, Zhe Li, Bingsong Yan, Jiatong Lin, Chuanxia Chen, Libing Zhang, Yizhong Lu
Abstract
The spontaneous accumulating nature and undesirable catalytic activity of nanosized noble-metal nanoparticle-based nanozymes significantly limit their applications in the bioanalytical field. Herein, by combining surface modification and nonprecious metal doping strategies, polydopamine-dressed PdCu alloy (PDA-PdCu) nanozymes with nanochain networks are successfully prepared through a facile one-pot NaBH4 reduction method. It is found that dopamine can shorten the gel formation time and Cu is indispensable for the formation of jelly-like PDA-PdCu samples with chain-like structures. Notably, benefiting from the improved Pd(0)/Pd(II) ratio, the enhanced substrate affinity, and the increased active surface area, the synthesized PDA-PdCu samples exhibit considerably enhanced oxidase mimetic activity compared to PDA-Pd and PdCu nanozymes. By making full use of the enhanced oxidase-like activity of PDA-PdCu and using 3,3′,5,5′-tetramethylbenzidine as a chromogenic substrate, a sensitive and straightforward colorimetric biosensing strategy for ascorbic acid (AA)-related bioenzyme activity, including the AA-generating alkaline phosphatase (ALP) and α-glucosidase (α-Glu) as well as the AA-consuming ascorbic acid oxidase (AA-ox), is elaborately developed. This work not only elucidates that the performance of the nanozyme can be modulated simultaneously by composition and surface modification but also provides a new versatile colorimetric sensing platform for AA-related bioenzymes.