Porous Oxyhydroxide Derived from Metal–Organic Frameworks as Efficient Triphosphatase-like Nanozyme for Chromium(III) Ion Colorimetric Sensing

Abstract

The dephosphorylation that involves the removal of a phosphate group from a substrate molecule plays a significant role in living organisms. An enzyme mimic (nanozyme) with phosphatase-like catalytic activity has recently received attention in terms of its capacity for dephosphorylation. In this study, three types of highly porous oxyhydroxide with remarkable triphosphatase-like catalytic activities, ZrOOH, GdOOH, and HfOOH, have been prepared through the transformation of metal−organic frameworks (MOFs) using a simple alkaline hydrolysis method. The triphosphatase mimetic activities of ZrOOH, GdOOH, and HfOOH were then thoroughly investigated and verified. In particular, an isotopic tracing experiment revealed that abundant surface hydroxyls could serve as nucleophilic agents to directly attack the electropositive phosphorus atom, causing the cleavage of the terminal phosphoester bonds of phosphoester substrate molecules. The kinetic analysis provided calculated values of K m of 105.7, 90.5, and 46.1 μM, while the V max values were 3.57, 4.76, and 2.74 × 10 −8 M s −1 and E a values were estimated to be 47.52, 41.15, and 52.79 kJ/mol for ZrOOH, GdOOH, and HfOOH, respectively. The chromium(III) ions acting as "poisoning" inhibitors efficiently downregulated the triphosphatase mimetic activity of GdOOH. On the basis of this effect, a colorimetric chromium(III) ion-sensing system was explored, which provided a relevant linear response range for the detection of chromium(III) ions of 5.0−200 μM and a low detection limit of 0.84 μM. This work not only shows the great potential of ZrOOH, GdOOH, and HfOOH as triphosphatase nanozymes but also deepens our understanding of the role of surface hydroxyls on phosphatase-mimicking nanozyme catalytic dephosphorization, which could be used in the rational design of phosphatase-mimicking nanozymes. Furthermore, the developed colorimetric sensing system could be applied to chromium(III) ion detection in biological systems.

Direct and Specific Detection of Glyphosate Using a Phosphatase-like Nanozyme-Mediated Chemiluminescence Strategy

“…As mentioned above, the UIO-66 precursor has no phosphatase-like activity and only can hydrolyze the phosphate group after being treated with an alkaline solution to generate ZrO X -OH. The reason may be that the rich −OH on the surface of ZrO X -OH as a nucleophilic agent attacked the electropositive phosphorus atom, leading to the cleavage of the P–O bonds. , Therefore, it can be deduced that −OH on the surface of ZrO X -OH plays a very important role in phosphatase-like activity. To evaluate the relationship between −OH on the surface of ZrO X -OH and phosphatase-like activity, we explored the effects of pH and organic acids on the activity of ZrO X -OH nanozymes.…”

Dipeptide Surface Modification and Ultrasound Boosted Phosphatase-Like Activity of the Ceria Nanozyme: Dual Signal Enhancement for Colorimetric Sensors

“…In addition, the bubble–liquid–particle triphase interface region promotes the generation of ROS to trigger the surface hydroxylation of the CMNC nanoparticles. Our previous work confirmed that the surface hydroxyl groups present in phosphatase-mimicking nanozymes play an extremely important role in ensuring a phosphatase-like activity. In the current system, we therefore assumed that the abundance of surface hydroxyl groups on the CMNC nanoparticles could serve as nucleophilic agents to directly attack the electropositive phosphorus atoms of the phosphoester substrates and enhance the catalytic dephosphorylation activity.…”

Recent progress in nanozyme-based sensors for ion detection: strategies, trends, and challenges

“…22 Recently, some nanomaterial-based phosphatase mimics to facilitate the hydrolysis of phosphate esters have emerged for ion analysis. 31,66,70 For instance, Song et al demonstrated that single-atom Ce-N-C has good phosphatase activity, 70 which could catalyze the dephosphorylation of organophosphates. Simultaneously, they discovered that Al 3+ could specifically attach to the O atom in the nanozyme, inhibiting its phosphatase-like activity.…”

“…On the other hand, H 2 O 2 is a redox agent, and the use of high-concentration H 2 O 2 may change the form of analytes in original samples. Instead, a few studies have explored the use of oxidases, 64,65 oxidoreductases, 21,22 phosphatase mimics 31,66 or multiactivity nanozymes 24,67,68 for toxic ion detection. For instance, using ascorbic acid-coated platinum nanoparticles (AA-PtNPs) with catalase properties to catalyze the decomposition of H 2 O 2 to produce hydrogen gas, the produced gas can expel water from the device, leading to a reduction in the weight of the device, 69 and because Ag + can inhibit the AA-PtNPs' catalytic activity and reduce gas production, it is possible to measure the Ag + content by observing changes in the device's weight (Fig.…”