Localized surface plasmon resonance (LSPR) is a phenomenon derived from the interaction between light and nanostructures, and its outcomes have been explored mainly for applications in surface-enhanced Raman spectroscopy (SERS), phototherapy, and catalysis. Bimetallic nanostructures are able to synergically combine the properties of two different metals to create a tuned response to LSPR according to their composition, shape, and morphology. In this study, an in situ synthesis of AgAu bimetallic hollow nanoshells (NS) over layered graphene oxide (GO) and silica submicrospheres (SiO 2 ) is presented. The synthesized structures acted as peroxidase-like nanozymes in the plasmon-enhanced electrochemical sensing of H 2 O 2 . The nanozymes were submitted to 405, 533, and 650 nm laser irradiation while performing the hydrogen peroxide reduction reaction (HPRR) with a fast response speed (4 s), exhibiting enhancements in sensitivity of 122% (for Ag 79 Au 21 /GO at 533 nm, 787 μA mM −1 cm −2 ), 105% (for Ag 79 Au 21 /GO at 405 nm, 725 μA mM −1 cm −2 ), and 119% (for Ag 50 Au 50 /SiO 2 at 650 nm, 885 μA mM −1 cm −2 ) compared to the dark conditions when matching the LSPR band maximum for each synthesized structure. When laser stimuli did not match LSPR band maximum, lower enhancements were achieved in both cases. According to Michaelis−Menten enzyme kinetics, the nanozymes I max followed the same LSPR bias and K m app was lowered after LSPR stimuli, showing the smallest values upon 405 nm irradiation (0.599 mM for Ag 79 Au 21 /GO and 0.228 mM for Ag 50 Au 50 /SiO 2 ) demonstrating increased substrate affinity in comparison to values previously reported in enzymatic and nonenzymatic biosensors of H 2 O 2 . Thus, we propose that LSPR is the main mechanism involved in the faster electron transfer rates and the consequent enhancement of electrochemical H 2 O 2 sensitivities, I max , and K m app by the bimetallic nanozymes synthesized by this approach.

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Silver-gold nanoalloys were prepared from their metal salts precursors through bottom-up mechanochemical synthesis, using one-pot or galvanic replacement reaction strategies. The nanostructures were prepared over amorphous SiO2 as an inert supporting material, facilitating their stabilization without the use of any stabilizing agent. The nanomaterials were extensively characterized, confirming the formation of the bimetallic nanostructures. The nanoalloys were tested as catalysts in the hydrogenation of 2-nitroaniline and exhibited up to 4-fold the rate constant and up to 37% increased conversion compared to the respective single metal nanoparticles. Our approach is advantageous to produce nanoparticles with clean surfaces with available catalytic sites, directly in the solid-state and in an environmentally friendly manner.

The interaction of metallic nanoparticles with light excites a local surface plasmon resonance (LSPR). This phenomenon enables the transfer of hot electrons to substrates that release Reactive Oxygen Species (ROS). In this context, the present study was aimed at enhancing the antibacterial effect of citrate-covered silver nanoparticles (AgNPs), which already possess excellent antimicrobial properties, via LSPR excitation with visible LED against Pseudomonas aeruginosa, one of the most refractory organisms to antibiotic .

The remote control of biocatalytic processes in an extracellular medium is an exciting idea to deliver innovative solutions in the biocatalysis field. With this purpose, metallic nanoparticles (NPs) are great candidates, as their inherent thermal, electric, magnetic, and plasmonic properties can readily be manipulated upon external stimuli. Exploring the unique NP properties beyond an anchoring platform for enzymes brings up the opportunity to extend the efficiency of biocatalysts and modulate their activity through triggered events. In this review, we discuss a set of external stimuli, such as light, electricity, magnetism, and temperature, as tools for the regulation of nanobiocatalysis, including the challenges and perspectives regarding their use. In addition, we elaborate on the use of combined stimuli that create a more refined framework in terms of a multiresponsive system. Finally, we envision this review might instigate researchers in this field of study with a set of promising opportunities in the near future.