Titania-coated gold nanorods with expanded photocatalytic response. Enzyme-like glucose oxidation under near-infrared illumination

Abstract

Gold nanorods coated with a uniform titanium dioxide nanoshell have been prepared and used as glucose-oxidase surrogates. Remarkably, this core-shell photocatalytic nanostructure has been able to induce complete oxidation of glucose at near room temperature (32-34 °C) in a wide range of pH values with the aid of a near-infrared (NIR) irradiation source. In contrast, the uncoated gold nanorods exhibit negligible photo-oxidation response under identical experimental conditions thereby proving the photoactivity of the titania shell towards glucose oxidation. The process takes place via in situ photo-generation of singlet oxygen or hydroxyl radicals as reactive oxidative species (ROS). This underlines the role played by the core nanorods as plasmonic light harvesters in the NIR range and constitutes the first example of a NIR-activated enzyme-like catalyst.

In-Situ Deposition of Plasmonic Gold Nanotriangles and Nanoprisms onto Layered Hydroxides for Full-Range Photocatalytic Response towards the Selective Reduction of p-Nitrophenol

“…Thus, catalytic activity must be carried out by the smaller facets (100) corners and (110) triangle thickness or the highly under-coordinated Au sites at the sharp facet's intersections. These corners may form Schottky barriers in the interface with the solid helping to avoid the recombination of carriers generated upon excitation and thus increasing the photocatalytic activity [10,[43][44][45]. The contribution of GNT to the photocatalysts at visible and infrared wavelength may be provided by the concentration of plasmonic near-field enhancement at the triangle corners creating highly energetic hot spots [31,[45][46][47].…”

“…As a general rule, bigger nanoparticles as well as more complex morphologies lead to longer red shifted absorptions in the LSPR. In fact, there are currently great research efforts on the photocatalytic field to shift the absorption capabilities and span the photo-response of catalysts towards the visible-NIR range, thereby maximizing the use of natural sunlight as a green and clean energy source [9][10][11].…”

Gold-Based Nanoparticles on Amino-Functionalized Mesoporous Silica Supports as Nanozymes for Glucose Oxidation

“…First of all, formation of GA was indirectly validated by UV-Vis spectroscopy. GA can selectively react with hydroxylamine and a trivalent iron salt form a red-colored hydroxamate complex with a broad absorption centered at 505 nm (see Figure 2a,c) [12,70]. Figure 2d shows the evolution of the absorption band of the hydroxamate complex at different pH values and confirms poorer performance of the Au-MCM-41 catalyst under basic conditions.…”

“…To quantify the glucose-oxidase enzyme mimicking activity of the Au-MCM-41 nanocatalyst, a kinetic study of the glucose conversion into gluconic acid was carried out. The kinetic parameters were determined after performing a series of experiments with increasing concentrations of glucose ( Figure 5a) and adjusting the gluconic acid generated after 30 min of reaction by quantitative colorimetric assays that included pH titration [50,71] and UV-Vis spectroscopy [70,72] (see Experimental section for further details). The data were fitted to a non-linear regression of the Michaelis-Menten equation and the apparent kinetic parameters were obtained using the Lineweaver-Burk double reciprocal plot as previously suggested by Gao et al [73] (see inset in Figure 5a).…”

Triangular and Prism‐Shaped Gold‐Zinc Oxide Plasmonic Nanostructures: In situ Reduction, Assembly, and Full‐Range Photocatalytic Performance

“…The different shapes and sizes of plasmonic nanoparticles give rise to distinct plasmon absorption bands in the visible and/or NIR range , , , . Particles which possess edges, like triangles, exhibit highly localized charge accumulation events and larger reactivity when compared to spherical ones of the same average size .…”