posted on 2022-01-18, 16:36authored byChenghui Zhang, Wendong Liu, Zhe Li, Bingsong Yan, Jiatong Lin, Chuanxia Chen, Libing Zhang, Yizhong Lu
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.