Showing papers by "Xingfa Gao published in 2023"
TL;DR: In this article , a carbon dot (C-dot) SOD nanozyme with a catalytic activity of over 10,000 U/mg, comparable to that of natural enzymes was reported.
Abstract: Nanozymes with superoxide dismutase (SOD)-like activity have attracted increasing interest due to their ability to scavenge superoxide anion, the origin of most reactive oxygen species in vivo. However, SOD nanozymes reported thus far have yet to approach the activity of natural enzymes. Here, we report a carbon dot (C-dot) SOD nanozyme with a catalytic activity of over 10,000 U/mg, comparable to that of natural enzymes. Through selected chemical modifications and theoretical calculations, we show that the SOD-like activity of C-dots relies on the hydroxyl and carboxyl groups for binding superoxide anions and the carbonyl groups conjugated with the π-system for electron transfer. Moreover, C-dot SOD nanozymes exhibit intrinsic targeting ability to oxidation-damaged cells and effectively protect neuron cells in the ischemic stroke male mice model. Together, our study sheds light on the structure-activity relationship of C-dot SOD nanozymes, and demonstrates their potential for treating of oxidation stress related diseases.
37 citations
TL;DR: In this paper , the authors present a review of the computational studies that closely interplay with the experiments and provide a historic overview of how the computations promote the understanding of the microscopic mechanisms and kinetics of nanozymes.
Abstract: Nanozymes usually refer to inorganic nanomaterials with enzyme-like catalytic activities. The research of nanozymes is one of the hot topics on the horizon of interdisciplinary science involving materials, chemistry, and biology. Although great progress has been made in the design, synthesis, characterization, and application of nanozymes, the study of the underlying microscopic mechanisms and kinetics is still not straightforward. Density functional theory (DFT) calculations compute the potential energy surfaces along the reaction coordinates for chemical reactions, which can give atomistic-level insights into the micro-mechanisms and kinetics for nanozymes. Therefore, DFT calculations have been playing an increasingly important role in exploring the mechanisms and kinetics for nanozymes in the past years. The calculations either predict the microscopic details for the catalytic processes to compliment the experiments or further develop theoretical models to depict the physicochemical rules. In this work, the corresponding research progress will be summarized. Particularly, the review will be focused on the computational studies that closely interplay with the experiments. The relevant experimental results without DFT calculations will be also briefly discussed to offer a historic overview of how the computations promote the understanding of the microscopic mechanisms and kinetics of nanozymes. This article is protected by copyright. All rights reserved.
2 citations
TL;DR: In this paper , a surface engineering strategy is employed to improve the specific activity of Ru nanozymes using charge-transferrable ligands such as polystyrene sulfonate (PSS), and the modified Ru-POD nanozyme is successfully used to develop an immunoassay for human alpha-fetoprotein (AFP) and achieves a 140fold increase in detection sensitivity compared with traditional HRP-based ELISA.
Abstract: Nanozymes have great potential to be used as an alternative to natural enzymes in a variety of fields. However, low catalytic activity compared with natural enzymes limits their practical use. It is still challenging to design nanozymes comparable with their natural counterparts in terms of specific activity. In this study, a surface engineering strategy is employed to improve the specific activity of Ru nanozymes using charge-transferrable ligands such as polystyrene sulfonate (PSS). PSS modified Ru nanozyme exhibits a peroxidase (POD)-like specific activity of up to 2820 U mg-1 , which is twice that of horseradish peroxidase (HRP) (1305 U mg-1 ). Mechanism studies suggest that PSS readily accepts negative charge from Ru, thus reducing the affinity between Ru and ·OH. Importantly, the modified Ru-POD nanozyme is successfully used to develop an immunoassay for human alpha-fetoprotein (AFP) and achieves a 140-fold increase in detection sensitivity compared with traditional HRP-based ELISA. Therefore, this work provides a feasible route to design nanozyme with high specific activity that meets the practical use as an alternative to natural enzyme. This article is protected by copyright. All rights reserved.
1 citations
TL;DR: In this paper , the integration of single-walled carbon nanotubes and graphene oxide into the endogenous carbon flow through degradation and fermentation, mediated by the gut microbiota of mice using isotope tracing and gene sequencing was uncovered.
Abstract: Carbon-based nanomaterials (CNMs) have recently been found in humans raising a great concern over their adverse roles in the hosts. However, our knowledge of the in vivo behavior and fate of CNMs, especially their biological processes elicited by the gut microbiota, remains poor. Here, we uncovered the integration of CNMs (single-walled carbon nanotubes and graphene oxide) into the endogenous carbon flow through degradation and fermentation, mediated by the gut microbiota of mice using isotope tracing and gene sequencing. As a newly available carbon source for the gut microbiota, microbial fermentation leads to the incorporation of inorganic carbon from the CNMs into organic butyrate through the pyruvate pathway. Furthermore, the butyrate-producing bacteria are identified to show a preference for the CNMs as their favorable source, and excessive butyrate derived from microbial CNMs fermentation further impacts on the function (proliferation and differentiation) of intestinal stem cells in mouse and intestinal organoid models. Collectively, our results unlock the unknown fermentation processes of CNMs in the gut of hosts and underscore an urgent need for assessing the transformation of CNMs and their health risk via the gut-centric physiological and anatomical pathways.
1 citations
TL;DR: In this article , the linker orbital energy model has been proposed by density functional theory calculations, which can be used to design catalytic activity of metal nodes of MOFs by engineering the electronic properties of linkers and substituents.
Abstract: Abstract The Hammett equation is commonly used to theoretically depict the remote electronic effects of substituents on catalytic activities of metal nodes of metal-organic frameworks (MOFs). However, the application of the theory to MOF catalysts usually encounters problems because it relies heavily on empirical parameters with unknown transferability. To develop an alternative prediction theory, the linker orbital energy model has been proposed by density functional theory calculations. The model provides a simple method to approximately depict the remote electronic substituent effects on catalytic activities of metal nodes of MOFs, and its general applicability to MOFs is supported by extensively revisiting the structure-activity relationships reported in the literatures. The model can be used to design catalytic activity of metal nodes of MOFs by engineering the electronic properties of linkers and substituents.
TL;DR: In this paper , contorted hexabenzocoronene (c-HBC) derivatives with good solubility are adopted to synthesize c-MOFs, and three c-MoFs with substantially different geometries and packing modes have been synthesized using three multitopic catechol-based c-hBC ligands with different symmetries and coordination numbers, respectively.
Abstract: Conductive metal-organic frameworks (c-MOFs) with outstanding electrical conductivities and high charge carrier mobilities are promising candidates for electronics and optoelectronics. However, the poor solubility of planar ligands greatly hinders the synthesis and widespread applications of c-MOFs. Nonplanar ligands with excellent solubility in organic solvents are ideal alternatives to construct c-MOFs. Herein, contorted hexabenzocoronene (c-HBC) derivatives with good solubility are adopted to synthesize c-MOFs. Three c-MOFs (c-HBC-6O-Cu, c-HBC-8O-Cu, and c-HBC-12O-Cu) with substantially different geometries and packing modes have been synthesized using three multitopic catechol-based c-HBC ligands with different symmetries and coordination numbers, respectively. With more metal coordination centers and increased charge transport pathways, c-HBC-12O-Cu exhibits the highest intrinsic electrical conductivity of 3.31 S m-1. Time-resolved terahertz spectroscopy reveals high charge carrier mobilities in c-HBC-based c-MOFs, ranging from 38 to 64 cm2 V-1 s-1. This work provides a systematic and modular approach to fine-tune the structure and enrich the c-MOF family with excellent charge transport properties using nonplanar and highly soluble ligands.