Optical Control of Biomimetic Nanoparticle Catalysts Based upon the Metal Component

Abstract

Nanoparticle catalysts provide an intriguing route to achieving sustainable reactivity. Recent evidence has suggested that both the underlying metallic core and the passivating ligand layer can be exploited to control reactivity. The intimate interactions between the core metal and structure of the ligand layer can change based upon the metal used to generate the catalytic particle. Through judicious selection of both components, nanoparticle catalytic systems can be designed to be stimuli responsive for controlled reactivity. Herein, we demonstrate the effects of the underlying metal on the optically modulated catalytic activity of peptide-capped noble metal nanoparticles. For this, a photoswitch was incorporated into the peptide that enables reversible reconfiguration of the bioligand overlayer structure between two conformations based upon the isomerization state of the photoswitch. These changes in activity are dependent upon the inorganic metal of the particle core, and we exploit this dependence to demonstrate changes in the activity. The materials were fully characterized via spectroscopic methods and microscopy to correlate the observed reactivity to the material composition. The results provide new pathways to achieve remotely responsive catalysts that could be important for controlled multistep reactions or be exploited for other applications including biosensing and plasmonic devices.

Photoswitchable Catalysis Mediated by Nanoparticles

“…Yet another study [14c] of the same authors focused on the influence of metal core on switchability. Palladium (PdNPs) and silver (AgNPs) nanoparticles were prepared with previously studied AuBP1C and CAuBP1 peptides.…”

“…Since then, the research has been solely continued on nanoparticles due to the large surface to volume ratio they offer in comparison to bulk materials. [13][14][15][16][17][18][19] Figure 2 outlines the main concepts of photoswitchable catalysis mediated by nanoparticles. The surface, interligand and interparticle space have been successfully utilized, as discussed below.…”

Atomically Resolved Characterization of Optically Driven Ligand Reconfiguration on Nanoparticle Catalyst Surfaces

“…3,4 A second stimulus can then be used to return the ligands to the initial configuration with negligible structural changes in the inorganic component. 5 Such materials could make immediate impacts for applications in targeted drug delivery, biosensing, information storage, catalysis, and so on. 6−8 Unfortunately, the ability to remotely and reversibly actuate structural changes of ligands bound to a NP surface is highly challenging.…”

“…9,10 In addition, the external stimulus also needs to be of sufficiently low enough energy such that it does not adversely affect or degrade the material. 5 For instance, optical irradiation with light may be an ideal stimulus over heat that could lead to particle degradation and bulk precipitation. 11,12 Taking all of these ligand/NP structural considerations into account and the external stimulus factors for responsive structural changes, the complexity of these responsive material systems is raised.…”

“…3 With the ability to change the bioligand overlayer structure between two different conformations, changes in the NP catalytic reactivity have been observed. 5,13 To this end, when Au NPs capped the AuBP1 peptide with the photoswitch incorporated at the C-terminus (termed AuBP1C-MAM) was used to drive catalytic reduction of 4-nitrophenol (4-NP) in water, the reaction was notably faster with the peptides in the trans conformation over the cis. 13 This difference in reactivity was the result of a higher activation energy for the NPs in the cis conformation as compared to those in the trans.…”