SERS Resolving of the Significance of Acetate on the Enhanced Catalytic Activity of Nanozymes

Abstract

Understanding the structure−activity correlation and reaction mechanism of the catalytic process in an acetic acid−sodium acetate (HAc-NaAc) buffer environment is crucial for the design of efficient nanozymes. Here, we first reported a lattice restructuration of Au-LaNiO 3−δ nanofibers (NFs) after acidification with the HAc-NaAc buffer to show a significantly enhanced oxidase-like property. Surface-enhanced Raman spectroscopy (SERS) and density functional theory (DFT) calculation confirm the direct evidence for the formation of specific enhanced intermediate O−O species after acidification, indicating that the insertion of the carboxyl group in the A-Au/LaNiO 3−δ NFs plays crucial roles in both producing vacancies in HAc-NaAc solution from its dissociation during the catalytic process and the protection of the vacancies, which can be directly interacted with oxygen in the environment to produce O−O species, realizing the enhanced oxidation of substrate molecules. The insertion of the carboxyl group increased the oxidase-like catalytic activity by 2.38 times and the SERS activity by 5.27 times. This strategy offers a way to construct an efficient nanozyme-linked immunosorbent assay system for the diagnosis of cancer through the highly sensitive SERS identification of exosomes.

Signal Amplification Strategy Design in Nanozyme‐Based Biosensors for Highly Sensitive Detection of Trace Biomarkers

“…The catalytic activity of enzymes in various enzyme‐catalyzed reactions is usually highly dependent on the external pH. In a study by Zhao et al., [ 231 ] they achieved the formation of A‐Au/LaNiO 3 ‐δ nanofibers (NFs) by reorganizing the lattice structure of Au/LaNiO 3 ‐δ NFs through acidification with HAc‐NaAc (pH = 4) for 7 days. During this acidification process, the incorporation of carboxyl groups into the A‐Au/LaNiO 3 ‐δ NFs facilitated a direct interaction with oxygen in the surrounding environment.…”

“…The catalytic activity of enzymes in various enzyme-catalyzed reactions is usually highly dependent on the external pH. In a study by Zhao et al, [231] they achieved the formation of A-Au/LaNiO 3 -𝛿 nanofibers (NFs) by reorganizing the lattice struc-Figure 13. Au-based nanozymes enhance SERS signals through increased "hot spots" generation.…”

“…Copyright 2022, American Chemical Society. E) Schematic illustration of the mechanism of lattice restructuration with A-Au/LaNiO 3 NFs [231]. F) The CT and LSPR mechanism of SERS enhancement of oxTMB; G) SERS detection for exosomes.…”

“…F) The CT and LSPR mechanism of SERS enhancement of oxTMB; G) SERS detection for exosomes. Reproduced with permission [231]. Copyright 2022, American Chemical Society.…”

SERS Tracking Oxidative Stress on a Metalloporphyrin Framework by Vitamin C

“…51 Generally, the change of the UV−vis absorption spectrum is closely related to the concentration of molecules and can directly reflect the catalytic process in the reaction system, while the change of the SERS spectrum is related to both the concentration of molecules and the SERS activity of substrate materials, so it reflects the change of both the catalytic process and SERS sensitivity. 52 In order to further understand the changes of UV−vis absorbance and SERS intensities in the peroxidase-like reaction process on the reduced MPF nanosheets, the results in Figure S13 were obtained by dividing the spectral intensity of oxTMB on the MPF substrate after the treatment by different proportions of VC with that of the spectral intensity on the MPF nanosheets without the VC treatment. The UV−vis absorption intensity ratio changes slightly with time, even decreasing; however, the SERS intensity ratio still increases significantly after 10 min.…”