Facet Energy versus Enzyme-like Activities: The Unexpected Protection of Palladium Nanocrystals against Oxidative Damage

Abstract

To develop nanomaterials as artificial enzymes, it is necessary to better understand how their physicochemical properties affect their enzyme-like activities. Although prior research has demonstrated that nanomaterials exhibit tunable enzyme-like activities depending on their size, structure, and composition, few studies have examined the effect of surface facets, which determine surface energy or surface reactivity. Here, we use electron spin-resonance spectroscopy to report that lower surface energy {111}-faceted Pd octahedrons have greater intrinsic antioxidant enzyme-like activity than higher surface energy {100}-faceted Pd nanocubes. Our in vitro experiments found that those same Pd octahedrons are more effective than Pd nanocubes at scavenging reactive oxygen species (ROS). Those reductions in ROS preserve the homogeneity of mitochondrial membrane potential and attenuate damage to important biomolecules, thereby allowing a substantially higher number of cells to survive oxidative challenges. Our computations of molecular mechanisms for the antioxidant activities of {111}- and {100}-faceted Pd nanocrystals, as well as their activity order, agree well with experimental observations. These findings can guide the design of antioxidant-mimicking nanomaterials, which could have therapeutic or preventative potential against oxidative stress related diseases.

Synthesis of Pt Hollow Nanodendrites with Enhanced Peroxidase‐Like Activity against Bacterial Infections: Implication for Wound Healing

“…Platinum (Pt)‐based nanocrystals have been widely applied in electronics, photonics, sensing, energy conversion, biomedicine, and particularly in catalysis, due to their well‐controlled shape, size, morphology and structure . In recent years, a series of strategies have been employed to improve the catalytic efficiency of Pt nanocrystals, such as reducing particle size, combining Pt with other metals, and synthesis of hollow structures or high‐index facet nanocrystals.…”

Diagnosis of rubella virus using antigen-conjugated Au@Pt nanorods as nanozyme probe

“…[9][10][11][12] As nanotechnology advances fast, the nanozymes which could replace protein enzymes in bioanalytical assays bring a new opportunity to the development of simple and sensitive diagnostic tools. [13][14][15][16] Nanozymes comprise many types of materials, iron oxide, vanadium oxide, cerium oxide, manganese oxide, gold, platinum, palladium, gold-silver alloys, carbon nanotubes, graphene, metal chalcogenides, and other [17][18][19][20][21][22][23][24][25][26] Compared with natural enzymes, nanozymes are advantageous in several aspects, such as low cost, ease of mass production, robustness to harsh environments, high stability, long-term storage, large surface area for further modification and bioconjugation and so on. [27][28][29][30][31][32] Previously, we found Au-Pt core/shell nanorods (Au@Pt NRs) have intrinsic multiple enzyme mimetic capability, for example, oxidase, peroxidase, and catalase mimetic activity.…”

Nanozyme applications in biology and medicine: an overview

“…The peroxidase-like activity of CNTs have reported in another study [98]. The intrinsic peroxidase-like activity of single-walled carbon nanotubes (SWNTs) was investigated by Qu et al [74]. Similar to HRP, its activity was pH, temperature and H 2 O 2 dependent.…”

“…In a study by Ibrahim et al, an immunoassay was used for the detection of C-reactive protein (CRP) from rapid whole blood magnetic permeability. The assay employed monoclonal anti-CRP antibody conjugated to dextran iron oxide nanoparticles (70 nm) as superparamagnetic labels and polyclonal anti-CRP antibody conjugated to silica microparticles (to enhance sedimentation of the complex) [74]. Notably, nanoparticle biosensors with modified antibody provide three functions including capture, separation and detection [75].…”