Microfluidic Synthesis of Hybrid TiO₂-Anisotropic Gold Nanoparticles with Visible and Near-Infrared Activity

Abstract

Anisotropic gold nanoparticles (AuNPs), with their unique physical and optical properties, are emerging as smart and key nanomaterials and are being exploited in many crucial fields. To further improve their range of action, anisotropic AuNPs have been coupled with semiconductors, mainly TiO2 (titania), receiving great interest as powerful platforms both in biomedicine and in catalytic applications. Such hybrid nanoparticles show new properties that arise from the synergic action of the components and rely on NP size, morphology, and arrangement. Therefore, continuous advances in design and fabrication of new hybrid titania@gold NPs (TiO2@AuNPs) are urgent and highly desirable. Here, we propose an effective protocol to produce multibranched AuNPs covered by a controlled TiO2 thin layer, exploiting a one-pot microfluidic process. The proposed method allows the in-flow and reliable synthesis of titania-functionalized-anisotropic gold nanoparticles by avoiding the use of toxic surfactants and controlling the titania shell formation. TiO2@AuNPs have been fully characterized in terms of morphology, stability, and biocompatibility, and their activity in photocatalysis has been tested and verified.

X-ray Photoelectron Spectroscopy (XPS) Analysis of Ultrafine Au Nanoparticles Supported over Reactively Sputtered TiO2 Films

“…Metal oxide-supported catalyst nanoparticles (MO/C) are one of the most actively pursued catalyst systems for modern chemical applications, including the oxidation of volatile organic compounds, photocatalysis, and energy-harvesting materials [ 1 , 2 , 3 , 4 , 5 , 6 ]. Gold (Au), platinum (Pt), and ruthenium (Ru) nanoparticles (NP) are among the MO/C system types that possess an unexpectedly high catalytic activity, coupled with optical properties.…”

Gold Nanostars in Biology and Medicine: Understanding Physicochemical Properties to Broaden Applicability

“…Abalde-Cela et al have shown that gold nanostars can be synthesized in a droplet microfluidics device, where each drop represents a nanoreactor . Very recently, a report by Polito and co-workers has shown that microfluidics devices can not only synthesize gold nanostars with high reproducibility but also can be adapted to coat them with a conformal thin layer of TiO 2 , which opens the door to the opportunity to coat them with a wide range of other metal oxides or semiconducting materials …”

“…64 Very recently, a report by Polito and co-workers has shown that microfluidics devices can not only synthesize gold nanostars with high reproducibility but also can be adapted to coat them with a conformal thin layer of TiO 2 , which opens the door to the opportunity to coat them with a wide range of other metal oxides or semiconducting materials. 65 As I have alluded to in passing before, issues in monodispersity and reproducibility drastically affect the plasmonic response of gold nanostars. Differences in spike number, length, morphology, and orientation all affect the position, width, number, and intensity of the LSPR bands.…”

Controllable Synthesis of Silicon‐Based Nanohybrids for Reliable Surface‐Enhanced Raman Scattering Sensing

“…Recently, given the advantages of excellent mass and heat transfer, precise reaction control and multi‐channel, microfluidic technology has attracted extensive attention in the field of nanomaterial synthesis. [ 56‐60 ] Sugioka and his co‐workers synthesized layered Cu‐Ag nanodots deposited inside the 3D glass microfluidic channel by femtosecond laser direct writing ablation and femtosecond laser selective metallization. [ 57 ] The size and thickness of the decorated Cu‐Ag thin films could be controlled by regulating the laser parameters.…”