Glutathione-protected gold nanocluster decorated cadmium sulfide with enhanced photostability and photocatalytic activity

A Review on Gold Nanoclusters for Cancer Phototherapy

Cancer phototherapy, including photodynamic therapy (PDT) and photothermal therapy (PTT), has been extensively studied in recent years because of its noninvasive properties, high efficiency, improved selectivity, and reduced side effects. Gold nanoclusters (AuNCs) have the advantages of high biocompatibility, high biosafety, excellent photoresponse, and high tumor penetration ability. This review analyzes the use of AuNCs in tumor phototherapy in recent years from three aspects, namely, AuNCs in PDT, AuNCs in PTT, and AuNCs in combination therapy, and presents the high potential of AuNCs in cancer phototherapy. This review aims to provide readers with the unique advantages, diversified application approaches, and bright application prospects of AuNCs in phototherapy and to provide insights into strategies for applying AuNCs to tumor phototherapy.

Recent Progress on Ligand-Protected Metal Nanoclusters in Photocatalysis

The reckless use of non-replenishable fuels by the growing population for energy and the resultant incessant emissions of hazardous gases and waste products into the atmosphere have insisted that scientists fabricate materials capable of managing these global threats at once. In recent studies, photocatalysis has been employed to focus on utilizing renewable solar energy to initiate chemical processes with the aid of semiconductors and highly selective catalysts. A wide range of nanoparticles has showcased promising photocatalytic properties. Metal nanoclusters (MNCs) with sizes below 2 nm, stabilized by ligands, show discrete energy levels and exhibit unique optoelectronic properties, which are vital to photocatalysis. In this review, we intend to compile information on the synthesis, true nature, and stability of the MNCs decorated with ligands and the varying photocatalytic efficiency of metal NCs concerning changes in the aforementioned domains. The review discusses the photocatalytic activity of atomically precise ligand-protected MNCs and their hybrids in the domain of energy conversion processes such as the photodegradation of dyes, the oxygen evolution reaction (ORR), the hydrogen evolution reaction (HER), and the CO₂ reduction reaction (CO₂RR).

A Revealing Insight into Gold Cluster Photocatalysts: Visible versus (Vacuum) Ultraviolet Light

[Au₂₅(PPh₃)₁₀(SC₂H₄Ph)₅Cl₂]²⁺ (Au25) supported on TiO₂ (P25) exhibited distinct photocatalytic behaviors in the oxidation of amines using visible or ultraviolet light. The activity under visible light (455 nm) was superior to that under ultraviolet light. To gain insight into the origin of this difference, we investigated the photoreaction pathways of Au25 isolated in the gas phase upon irradiation with a pulsed laser with wavelengths of 455, 193, and 154 nm. High-resolution mass spectrometry revealed photon energy-dependent pathways for Au25: dissociation of the PPh₃ ligands and PPh₃AuCl units at 455 nm, dissociation into small [Au_nS_m]⁺ ions (n = 3-20; m = 0-4) at 193 nm, and ionization affording the triply charged state at 154 nm. These results were substantiated by density functional theory simulations. On the basis of these results, we proposed that the inferior photocatalytic activity of Au25/P25 under ultraviolet light is mainly due to the poor photostability of Au25.

Multifunctional fluorescent gold nanoclusters with enhanced aggregation-induced emissions (AIEs) and excellent antibacterial effect for bacterial imaging and wound healing

To explore new alternatives to combat increasing risk of bacterial infection, in this work, a cationic antimicrobial peptide (HHC10) and glutathione (GSH) co-ligand protected ultra-small gold nanoclusters (Au NCs) was constructed by a simple one-pot method. The intrinsic luminescent property of GSH-protected Au NCs (Au_xGSH) endowed enhanced aggregation-induced emissions (AIEs) of co-ligand-protected Au NCs (Au_xGSH-HHC10), which exhibited a very strong orange luminescence. Based on the AIE effect, for one thing, Au_xGSH could be applied to rapidly and selectively detect Gram-positive bacteria. For another, Au_xGSH-HHC10 exhibited potential for multicolor imaging of both Gram-negative and Gram-positive bacteria. Besides, as-synthesized Au_xGSH-HHC10 could act as potent nanoantibiotics against both Gram-negative and Gram-positive bacteria, which could not only avoid drug tolerance but also be effective toward drug-resistance bacteria. The antibacterial mechanism indicated that the synergetic effect of the generation of reactive oxygen species (ROS), binding with DNA, and broad-spectrum antibacterial activity of HHC10 led to the membrane damage, depolarization, and interference of biological function, thus enhancing the antibacterial effect. More importantly, such an Au NCs could realize excellent therapeutic outcomes for wound healing in vivo, and showed good biocompatibility and biosafety toward health tissues. The results will provide a great potential for the application of Au NCs for imaging-guided antibacterial platform.

Controlling Pt co-catalyst loading in a WO3 quantum dot and MoS2 nanosheet composite Z-scheme system for enhanced photocatalytic H2 evolution

A solid-state Z-scheme system, with the synergistic integration of the advantages of various narrow-band semiconductors, is considered to be a potential strategy to develop efficient photocatalysts for operation under visible light illumination. However, the charge separation efficiency of these systems has always been reduced by disordered electron transfer between coupling semiconductors. In this work, we constructed a direct Z-scheme system WO₃-MoS₂-Pt through the loading of WO₃ quantum dots onto MoS₂ nanosheets and the selective depositing of a Pt co-catalyst onto MoS₂. X-ray diffraction, transmission electron microscopy, atomic electron microscopy and x-ray photoelectron spectroscopy, etc were used to confirm the successful preparation of the targeted photocatalyst. This photocatalytic system showed high visible-light-driven H₂ evolution activity (802.2 μmol · h^-1 · g^-1) and good photostability. Control experiment and mechanism analysis suggested that the remarkable performance can be attributed to the heterojunction formed WO₃ and MoS₂ and the vectorial electron transfer (WO₃ → MoS₂ → Pt) achieved by selectively loading the Pt co-catalyst.