Engineering Two-Dimensional Pd Nanoplates with Exposed Highly Active {100} Facets Toward Colorimetric Acid Phosphatase Detection

Abstract

Enzyme-like activity and efficiency of nanomaterials are strongly controlled by their size, composition, and structure, and hence the structural parameters need to be optimized. Here, we report that two-dimensional Pd nanoplates enclosed by {100}-facets [{100}­PdSP@rGO] exhibit substantially enhanced intrinsic oxidase-like activities relative to the {111}-facets ones and Pd nanocubes in catalyzing the chromogenic reaction of 3,3′,5,5′-tetramethylbenzidine. By taking ascorbic acid 2-phosphate as the substrate, which transforms to ascorbic acid in the presence of acid phosphatase (ACP), the {100}­PdSP@rGO could be used as an efficient nanozyme for colorimetric ACP detection without resorting to destructive H2O2. A good linear relationship from 0.01 to 6.0 mU/mL with a detection limit of 8.3 μU/mL is obtained, which is better than most previously reported ACP assays. Importantly, the excellent assay performance could be successfully applied to ACP determination in serum samples with high accuracy. This study demonstrates that the enzyme-like activity of nanomaterials could be finely tuned simultaneously by controlling their exposed crystal facets and high specific surface area.

Colorimetric and Fluorescent Dual-Modality Sensing Platform Based on Fluorescent Nanozyme

“…Good linearity is obtained using colorimetric detection in the concentration range of 20∼5 mU/ml with an LOD of 14 μU/ml (S/N = 3) ( Figure 7B ). Comparison between determination of ACP using different electrodes is demonstrated in Supplementary Table S1 (SI) ( Hu et al, 2016 ; Deng et al, 2017 ; Chen et al, 2019b ; Lin et al, 2020 ; Zhang et al, 2021 ). The LOD is lower than that obtained from palladium square nanoplates on reduced graphene oxide (PdSP@rGO) ( Chen et al, 2019b ), chitosan modified platinum nanoparticles (Ch-PtNPs) ( Deng et al, 2017 ), and acridone derivative 10-benzyl-2-amino-acridone ( Zhang et al, 2021 ).…”

“…The possible oxidase, catalase, or superoxide dismutase (SOD)-mimicking activities of NGQDs were measured according to the literature ( Chen et al, 2019a ). The activity of oxidase was obtained by measuring the absorbance of TMB solution (0.5 mM in HAc-NaAc buffer, pH = 4.0) after it was directly oxidized by NGQDs (10 μg/ml).…”

“…The assay of catalase-mimicking activity is based on the decrease of characteristic UV absorption of H 2 O 2 (10 μM) at 240 nm after its decomposition catalyzed by NGQDs (10 μg/ml). The activity of superoxide dismutase was determined by the improved tetrazolium blue method ( Chen et al, 2019a ). Briefly, riboflavin was reduced under light conditions, and the reduction product produced •O 2 − in the presence of O 2 , which could further reduce nitrotetrazolium blue (NBT) to blue methylhydrazone with characteristic absorption at 560 nm.…”

Metal nanoparticles-based nanoplatforms for colorimetric sensing: A review

“…The linear range was 1-100 μM, and the detection limit was 10.6 nM. (Figure 4a) [73]. Taking ascorbic acid 2-phosphoric acid as substrate and converting to ascorbic acid in the presence of acid phosphatase (ACP), ACP can be efficiently detected without destroying H 2 O 2 .…”

“…Detect metals [77] and nonmetal ions [72]; detect acid phosphatase (ACP) [73]; detect biomolecules [75,79,80]; detect toxic substances [78].…”