Highly Crystalline Mesoporous Titania Loaded with Monodispersed Gold Nanoparticles: Controllable Metal-Support Interaction in Porous Materials

We report the syntheses of mesoporous Au/TiO₂ hybrid photocatalysts with ordered and crystalline frameworks using co-assembly of organosilane-containing colloidal amphiphile micelles (CAMs) and poly(ethylene oxide)-modified gold nanoparticles (AuNPs) as templates. The assembled CAMs can convert to inorganic silica during calcination at elevated temperatures, providing extraordinary thermal stability to preserve the porosity of TiO₂ and the nanostructures of AuNPs. Well-defined AuNPs supported within mesoporous TiO₂ (Au@mTiO₂) can be prepared using thermal annealing at temperatures up to 800 °C. High-temperature treatment (≥500 °C) under air is found to not only improve the crystallinity of TiO₂ but also induce oxidative strong metal-support interactions (SMSIs) at Au/TiO₂ interfaces. For oxidative SMSIs, the surface oxidation of AuNPs can generate positively charged Au^δ+ species, while TiO₂ gets reduced simultaneously. Using photocatalytic oxidation of benzyl alcohol as a model reaction, Au@mTiO₂ calcined at 600 °C for 12 h exhibited the best activity under UV irradiation, while Au@mTiO₂ calcined at 600 °C for 2 h showed the best activity under visible light. The delicate balance between the crystallinity and porosity of TiO₂ and the SMSIs at Au-TiO₂ interfaces is found to impact the photocatalytic activity of these hybrid materials.

Noble metal nanostructures in optical biosensors: Basics, and their introduction to anti-doping detection

Nanotechnology has illustrated significant potentials in biomolecular-sensing applications; particularly its introduction to anti-doping detection is of great importance. Illicit recreational drugs, substances that can be potentially abused, and drugs with dosage limitations according to the prohibited lists announced by the World Antidoping Agency (WADA) are becoming of increasing interest to forensic chemists. In this review, the theoretical principles of optical biosensors based on noble metal nanoparticles, and the transduction mechanism of commonly-applied plasmonic biosensors are covered. We review different classes of recently-developed plasmonic biosensors for analytic determination and quantification of illicit drugs in anti-doping applications. The important classes of illicit drugs include anabolic steroids, opioids, stimulants, and peptide hormones. The main emphasis is on the advantages that noble metal nano-particles bring to optical biosensors for signal enhancement and the development of highly sensitive (label-free) biosensors. In the near future, such optical biosensors may be an invaluable substitute for conventional anti-doping detection methods such as chromatography-based approaches, and may even be commercialized for routine anti-doping tests.

Hemin/Au nanorods/self-doped TiO2nanowires as a novel photoelectrochemical bioanalysis platform

A sensitive photoelectrochemical platform for GSH was developed by modifying self-doped TiO₂nanowires with mixed Au nanorods at two different aspect ratios as the core sensing unit and hemin for recognition.

Laser-induced fabrication of highly branched Au@TiO2 nano-dendrites with excellent near-infrared absorption properties

The highly branched Au@TiO₂ nano-dendrites with excellent near-infrared absorption properties have been conveniently fabricated via a novel and effective laser-induced strategy.