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Constructing highly proficient C–X (X = O, N, S, etc.) and C–C bonds by leveraging TMs (transition metals) (Fe, Cu, Pd, Rh, Au, etc.) and enzymes to catalyze carbene insertion into X–H/C(sp2)–H is a highly versatile strategy. This is primarily achieved through the in situ generation of metal carbenes from the interaction of TMs with diazo compounds. Over the last few decades, significant advancements have been made, encompassing a wide array of X–H bond insertions using various TMs. These reactions typically favor a stepwise ionic pathway where the nucleophilic attack on the metal carbene leads to the generation of a metal ylide species. This intermediate marks a critical juncture in the reaction cascade, presenting multiple avenues for proton transfer to yield the X–H inserted product. The mechanism of C(sp2)–H insertion reactions closely resembles those of X–H insertion reactions and thus have been included here. A major development in carbene insertion reactions has been the use of engineered enzymes as catalysts. Since the seminal report of a non-natural "carbene transferase" by Arnold in 2013, "P411", several heme-based enzymes have been reported in the literature to catalyze various abiological carbene insertion reactions into C(sp2)–H, N–H and S–H bonds. These enzymes possess an extraordinary ability to regulate the orientation and conformations of reactive intermediates, facilitating stereoselective carbene transfers. However, the absence of a suitable stereochemical model has impeded the development of asymmetric reactions employing a lone chiral catalyst, including enzymes. There is a pressing need to investigate alternative mechanisms and models to enhance our comprehension of stereoselectivity in these processes, which will be crucial for advancing the fields of asymmetric synthesis and biocatalysis. The current review aims to provide details on the mechanistic aspects of the asymmetric X–H and C(sp2)–H insertion reactions catalyzed by Fe, Cu, Pd, Rh, Au, and enzymes, focusing on the detailed mechanism and stereochemical model. The review is divided into sections focusing on a specific X–H/C(sp2)–H bond type catalyzed by different TMs and enzymes. [ABSTRACT FROM AUTHOR]

Cyclopentene rings possessing a chiral quaternary center are important structural motifs found in various natural products. In this work, we disclose expedient and efficient access to this class of synthetically valuable structures via highly enantioselective desymmetrization of prochiral propargylic alcohols. The efficient chirality induction in this asymmetric gold catalysis is achieved via two‐point bindings between a gold catalyst featuring a bifunctional phosphine ligand and the substrate homopropargylic alcohol moiety—an H‐bonding interaction between the substrate HO group and a ligand phosphine oxide moiety and the gold‐alkyne complexation. The propargylic alcohol substrates can be prepared readily via propargylation of enoate and ketone precursors. In addition to monocyclic cyclopentenes, spirocyclic and bicyclic ones are formed with additional neighboring chiral centers of flexible stereochemistry in addition to the quaternary center. This work represents rare gold‐catalyzed highly enantioselective cycloisomerization of 1,5‐enynes. Density functional theory (DFT) calculations support the chirality induction model and suggest that the rate acceleration enabled by the bifunctional ligand can be attributed to a facilitated protodeauration step at the end of the catalysis. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of seleno‐substituted chromenes from selenoalkynes and phenols. In this cascade reaction, the applied gold catalyst not only functions as a π‐acid, but also as a Lewis acid, enabling the propargylic substitution in the first step to connect the oxygen carbon bond. Under the optimal reaction condition a total of 26 chromenes were accessible by this modular access. During scale up experiments, the hydrolysis of the vinylselenium substructure to the corresponding chromenones was observed. By revisiting the electron‐rich starting materials, four chromenones were produced following a one‐pot reaction using a single gold catalyst. To better understand the interaction of gold and selenium, a series of nuclear magnetic resonance studies and high‐resolution mass spectrometry studies were performed, which led to the proposal of a mechanism for this transformation. [ABSTRACT FROM AUTHOR]

Cacumen platyclade extracts were utilized as the reducing agent to prepare Au/Al2O3 composites. XRD, BET, SEM, TEM were employed to characterize the properties of the catalyst. The catalytic activity of Au/Al2O3 was studied by using NaBH4 as the reducing agent and nitrophenol as the pollutant. The results showed that the Au/Al2O3 catalyst, calcinated at 400 °C, exhibited the highest catalytic activity. With a catalyst dosage of 1 g L−1, 2 mL NaBH4 of 0.15 mol L−1 could degrade 96.5 % nitrophenol in 21 min at 298 K, with a reaction constant of 0.16 min−1. Furthermore, the p-nitrophenol degradation ratio decreased by 0.8 % after ten cycles. [ABSTRACT FROM AUTHOR]

Thiolate‐protected Au nanoclusters (NCs) have developed as a promising class of model catalysts to achieve fundamental understanding of metal nanocatalysis. Whereas, the packing mode of peripheral ligand on metal core is changeful in the reaction medium and show elusive impact on catalytic activity. In this work, using glutathione (GSH) protected Au NCs (Au@GSH NCs) with aggregation‐induced‐emission (AIE) characteristics as model catalyst for the hydrogenation of 4‐nitrophenol (4‐NP), photoluminescence (PL) intensity correlated catalytic activity of Au@GSH NCs was successfully mediated by the addition of Ag+ in the preparation or poor solvent in the reaction medium, showing a relationship of “as one falls, another rises.” Au NCs with intense PL implied a dense packing of peripheral ligand, which hampered the accessibility of active site and thus exhibited slowest catalytic reaction kinetics of the reduction of 4‐NP and vice versa. Based on this methodology, a case study of the effect of salt additives on the catalytic activity is carried out, different mechanisms are distinguished by the change in the PL intensity, and with the combination of diagnostic deuterium isotope experiments, it has been demonstrated that the proton from water solvent is involved in the reaction and that the proton transfer process is the rate‐determining step, the contribution of ionic additives to the hydrogen bonding network determines their effect on the reaction kinetics. The correlation between PL intensity and catalytic activity of Au NCs could provide an efficient way to design highly active Au NC catalysts and give a new insight to understand the unique optoelectronic properties of Au NCs and reaction mechanism. [ABSTRACT FROM AUTHOR]

We reported nucleation mechanisms of InP directly on Si (8% lattice mismatch) under confined structures, called micro-crucibles, at ultra-high vacuum (UHV) by chemical beam epitaxy. These micro-crucibles are used to induce lateral growth in the presence of a micro-scale Au catalyst. It is found that at this UHV condition, the kinetics is dictated predominantly by adatom surface diffusion. Using a two-step growth process ((1) In-only exposure, then, (2) simultaneous In and P exposures), InP islands have been successfully nucleated on Si substrates under micro-crucible structures. The nucleation of these InP islands strongly depends on the metal catalyst location relative to the micro-crucible opening with metal catalysts residing closer to the opening having a higher chance to get incorporated with In and P atoms. Importantly, we found that using smaller micro-crucibles with double openings can increase the possibility of having metal catalysts reside near either opening and nucleate InP under micro-crucibles. [ABSTRACT FROM AUTHOR]

Computationally derived volcano curve has become the gold standard in catalysis, whose practical application usually relies on empirical interpretations of composition or size effects by the identical active site assumption. Here, we present a proof-of-concept study on disclosing both the support- and adsorbate-induced restructuring of Pt-Co bimetallic catalysts, and the related interplays among different interfacial sites to propose the synergy-dependent volcano curves. Multiple characterizations, isotopic kinetic investigations, and multiscale simulations unravel that the progressive incorporation of Co into Pt catalysts, driven by strong Pt-C bonding (metal-support interfaces) and Co-O bonding (metal-adsorbate interfaces), initiates the formation of Pt-rich alloys accompanied by isolated Co species, then Co segregation to epitaxial CoOx overlayers and adjacent Co3O4 clusters, and ultimately structural collapse into amorphous alloys. Accordingly, three distinct synergies, involving lattice oxygen redox from Pt-Co alloy/Co3O4 clusters, dual-active sites engineering via Pt-rich alloy/CoOx overlayer, and electron coupling within exposed alloy, are identified and quantified for CO oxidation (gas-phase), ammonia borane hydrolysis (liquid-phase), and hydrogen evolution reaction (electrocatalysis), respectively. The resultant synergy-dependent volcano curves represent an advancement over traditional composition-/size-dependent ones, serving as a bridge between theoretical models and experimental observations in bimetallic catalysis. Volcano curves have become the gold standard in catalyst design. Here, the authors propose synergy-dependent volcano curves by disclosing both support- and adsorbate-induced catalyst restructuring, ideally bridging the gap between theoretical models and experimental observations. [ABSTRACT FROM AUTHOR]

Vertically aligned carbon nanotubes (VACNTs) exhibit outstanding mechanical strength, chemical stability, and electrical characteristics; however, their constrained mechanical elasticity and chemical responsiveness spurred research on atomic decoration techniques for enhancing their mechanochemical attributes. Nevertheless, achieving uniform atomic decoration on the VACNT surface is difficult because of the high density and large aspect ratio of VACNT. Herein, a strategy to design and apply nanopatterned VACNTs (nVACNTs) based on a nanotransfer printing process is proposed to improve atomic penetrability. Nanopatterns inherent to nVACNTs facilitate atomic penetration, allowing for the more consistent and higher quality deposition of functional materials such as zinc oxide and alumina by atomic layer deposition. Furthermore, physical vapor deposition provides an improved coating of metal catalysts such as gold. The uniform deposition of ceramic layers on the entire surface of nVACNTs strengthens its mechanical resilience, owing to the diminished van der Waals forces of CNTs. Surface‐decorated nVACNTs display an increased sensitivity to NO2 gas, which is attributed to the enhanced quality of the reactive catalyst deposition and augmented permeability. This strategy achieves a larger decorated area while increasing a catalytically active reaction area. The obtained results promise that the enhanced nVACNTs will expand the industrial applications of carbon nanotubes. [ABSTRACT FROM AUTHOR]

Context: The field of chemistry has significantly evolved, with catalysis playing a crucial role in transforming chemical processes. From Valerius' use of sulfuric acid in the sixteenth century to modern advancements, catalysis has driven innovations across various industries. The introduction of gold as a catalyst marked a pivotal shift, expanding its applications beyond ornamentation to homogeneous catalysis. Gold's unique properties, such as its electrophilic nature and flexibility, have enabled its use in synthesizing complex molecules, including those in nanomedicine and sustainable chemical processes. The development of gold-based complexes, particularly in hydroalkoxylation and hydroamination reactions, showcases their efficiency in forming carbon–oxygen bonds under mild conditions. Recent studies on dual gold catalysis and heterobimetallic complexes further highlight gold's versatility in achieving high turnover rates and selectivity. This evolution underscores the potential of gold catalysis in advancing environmentally sustainable methodologies and enhancing the scope of modern synthetic chemistry. The debate about the nature of monogold and dual-gold catalysis is open. Methods: DFT calculations have played a key role in promoting the activation of alkynes, in particular the hydrophenoxylation of alkynes by metal-based catalysts. They not only help identify the most efficient and selective catalysts but also aid in screening for those capable of performing a dual metal catalytic mechanism. The most commonly used functionals are BP86 and B3LYP, with the SVP and 6-31G(d) basis sets employed for geometry optimizations, and M06 with TZVP or 6-311G(d,p) basis sets used for single-point energy calculations in a solvent. Grimme dispersion correction has been explicitly added either in the solvent single point energy calculations or in the gas phase geometry optimizations or in both. To point out that M06 implicitly includes part of this dispersion scheme. [ABSTRACT FROM AUTHOR]

A biomimetic nanoreactor that can mimick the chloroplasts in green plants is constructed through the self-assembly of cetyltrimethylammonium bromide (CTAB) bilayer on the surface of a gold nanorod (GNR) electrocatalyst. The CTAB bilayer of the nanoreactor imitates the chloroplast membrane to allow the selective transport of CO 2 and protons to the GNR core and the GNR core functions like Rubisco enzymes in chloroplast to catalyze CO 2 reduction reaction. Consequently, selective and efficient electrochemical reduction of CO 2 to CO is achieved on the chloroplast-like nanoreactor. Schematic structures of chloroplast and our chloroplast-mimicking nanoreactor for CO 2 reduction reaction (CO 2 RR). (a) The ingenious structure of chloroplast allows the selective transport of different species through phospholipid bilayer (chloroplast membrane) and subsequent photosynthetic CO 2 fixation via Rubisco enzyme catalysis occurring in chloroplast stroma. (b) Illustrations of our biomimetic design that employ cetyltrimethylammonium bromide (CTAB) bilayer-modified gold nanorod catalysts for CO 2 RR in aqueous solution. [Display omitted] [ABSTRACT FROM AUTHOR]

Gold nanoparticles (Au NPs) are unique catalysts due to their increased coordination unsaturation via nanoparticulation. Effective functioning requires an appropriate support to maintain particle dispersion without compromising nanoscale properties. Cross‐linked hydrophilic polymer‐derived hydrogels are ideal supports, particularly for biological and biomedical reactions, due to their aqueous affinity and biocompatibility. However, applications in confined spaces, such as in vivo environments, necessitate hydrogel micronization. This study introduces microsized DNA hydrogels as support for Au catalysts. DNA motif‐composed hydrogel particles exhibit high crosslinking density and produce small Au NPs owing to short DNA strands. This system significantly enhances catalytic efficiency compared to similar‐sized Au NP gel‐supported catalysts and requires minimal gold catalyst. Modulating DNA hydrogel crosslinking density allows easy control of Au NP size and catalytic activity, further improved by increased hydrogel surface area through microparticulation. These findings demonstrate DNA nanotechnology's versatility in tailoring DNA hydrogel properties and Au NP catalytic behavior. Computer‐aided design enables precise particle property and motif arrangement manipulation, offering promising customizable catalytic systems. [ABSTRACT FROM AUTHOR]

Constructing structurally robust and catalytically active metal nanoclusters for catalyzing multi‐component reactions is an interesting while challenging task. Inspired by Lewis acid and Lewis base catalysis, we realized the combination of both Lewis acid and Lewis base sites on the surface of a stable gold nanocluster Au35Cd2. The catalytic potential of Au35Cd2 in four‐component Ugi reaction was explored, demonstrating high activity and exceptional recyclability. In‐depth mechanism studies indicate that the catalytic synergy of the Lewis acid/base pair is crucial for the high efficiency of Au35Cd2‐catalyzed Ugi reaction. Bearing the stable structure, multiple activation sites and hierarchical chirality, Au35Cd2 is expected to display further interesting catalytic performance such as asymmetric catalysis. [ABSTRACT FROM AUTHOR]

An organophotocatalytic method has been described towards the synthesis of indolines and oxindoles starting from unusual α-chloro amide and N-(2-chlorophenyl)-N-alkyl methacrylamide substrates. This marks a notable improvement since the earlier syntheses utilized iridium and gold catalysts, and involved C–I or C–Br bond cleavage as the initial step. Our photocatalyst is a pincer ligand that can be easily deprotonated to make a very strong reducing agent. The reductive cleavage of the carbon–chloride bond, and subsequent 5-exo-trig ring cyclization, followed by hydrogen atom abstraction, prepare the desired heterocycles under very mild reaction conditions. An atom economic use of KOtBu has been shown to demonstrate the unusual trifunctional role of the latter. [ABSTRACT FROM AUTHOR]

Nanoporous gold (npAu) attracted increasing attention over the last 20 years as a highly active and selective oxidation catalyst in particular at low temperatures. Previous research mainly focused on npAu that was fabricated by corrosive dealloying of AuAg parent alloys. Yet, the use of other binary alloys, such as AuCu, promises interesting variations of the catalytic properties, when considering that residual amounts of the less noble metal were shown to be co‐catalytically involved. Aiming at providing a platform for systematic studies in this direction for Cu, we not only dealt with strategies for a reliable and reproducible preparation of npAu(Cu) catalysts from AuCu, but also with their potential for CO oxidation in comparison to npAu(Ag). We were able to develop an approach based on thermally quenched Au0.3Cu0.7 alloys, providing distinct synthetic advantages as a starting material for the catalyst fabrication versus the thermodynamically more stable AuCu3 intermetallic compound. Using PCD (potentiostatically controlled dealloying), well‐defined pore structures with ligament diameters of ∼40 nm and variable residual Cu concentrations in the range between ∼0.6 at % and ∼1.2 at % could be straightforwardly obtained. After activating such catalysts at 150 °C, they reproducibly showed catalytic activity for aerobic CO oxidation in a broad temperature window between 40 °C and 250 °C. As opposed to npAu(Ag), the activity increased with decreasing residual Cu content, outperforming the former at temperatures above ∼60 °C not only with respect to CO2 formation rates but also with respect to thermal stability. Based on X‐ray photoelectron spectroscopic and transmission electron microscopic results, it was possible to conclude that Cu segregates to the surface and, with rising Cu bulk content, increasingly occurs in form of Cu2+ species at the surface. While the latter are expected to be catalytically inactive, Cu and Cu+ species are likely candidates for the activation of oxygen being not possible on pure Au. [ABSTRACT FROM AUTHOR]

The direct auration of arenes is a key step in numerous gold‐catalyzed reactions. Although reported more than 100 years ago, understanding of its underlying mechanism has been hampered by the difficulties in the isolation of relevant intermediates given the propensity of gold(III) species to undergo reductive elimination. Here, we report the synthesis and isolation of a new family of intriguing zwitterionic [C(sp3)^C(sp2)]‐auracyclopentanes, as well as of their alkyl‐gold(III) precursors and demonstrate their value as mechanistic probes to study the C(sp2)‐Au bond‐forming event. Experimental investigations employing Kinetic Isotope Effects (KIE), Hammett plot, and Eyring analysis provided important insights into the formation of the auracycle. The data suggest a SEAr mechanism wherein the slowest step might be the π‐coordination between the arene and the gold(III) center, en route to the Wheland intermediate. We also show that these auracyclopentanes can work as catalysts in several gold‐promoted transformations. [ABSTRACT FROM AUTHOR]

Shape-controlled nanocrystals, such as nanoflowers, are expected to serve as innovative nanocatalysts with high catalytic activity. It is well-established that these nanocrystals can be readily synthesized with specific shapes using colloidal methods in solutions containing capping agents. However, these capping agents tend to reduce the catalytic activity of nanocatalysts. Therefore, it is imperative to remove these agents without altering the morphology to enhance catalytic efficiency. In this study, we developed a method for eliminating melamine, a common capping agent, from supported Au nanoflowers using water extraction and ultraviolet-ozone treatment. This process significantly enhances the catalytic performance, particularly for alcohol oxidation reactions such as the conversion of 1-phenylethyl alcohol to acetophenone. [ABSTRACT FROM AUTHOR]

Developing a desirable ethanol dehydrogenation process necessitates a highly efficient and selective catalyst with low cost. Herein, we show that the "complex active site" consisting of atomically dispersed Au atoms with the neighboring oxygen vacancies (Vo) and undercoordinated cation on oxide supports can be prepared and display unique catalytic properties for ethanol dehydrogenation. The "complex active site" Au−Vo−Zr3+ on Au1/ZrO2 exhibits the highest H2 production rate, with above 37,964 mol H2 per mol Au per hour (385 g H2 gAu-1 ${{\rm{g}}_{{\rm{Au}}}^{ - 1} }$ h−1) at 350 °C, which is 3.32, 2.94 and 15.0 times higher than Au1/CeO2, Au1/TiO2, and Au1/Al2O3, respectively. Combining experimental and theoretical studies, we demonstrate the structural sensitivity of these complex sites by assessing their selectivity and activity in ethanol dehydrogenation. Our study sheds new light on the design and development of cost‐effective and highly efficient catalysts for ethanol dehydrogenation. Fundamentally, atomic‐level catalyst design by colocalizing catalytically active metal atoms forming a structure‐sensitive "complex site", is a crucial way to advance from heterogeneous catalysis to molecular catalysis. Our study advanced the understanding of the structure sensitivity of the active site in atomically dispersed catalysts. [ABSTRACT FROM AUTHOR]

Ylide‐functionalized phosphines (YPhos) have been shown to yield highly active gold catalysts owing to their high donor capacity. To examine the impact of ylide functionalization on a given ligand structure, a series of ferrocenyl diphosphines functionalized with no, one or two ylide moieties and their corresponding bimetallic gold complexes were prepared. The complexes feature an anti‐conformation of the two phosphine moieties, guaranteeing the presence of two independent metal centers. Comparative studies of the complexes in the hydroamination and hydrohydrazination of alkynes revealed a significant increase in catalytic activity for each newly introduced ylide group. The di‐YPhos ligands were revealed to be the most active precatalysts, functioning effectively even at 0.1 or 0.2 mol % catalyst loading. This catalytic efficiency was demonstrated for a series of alkynes, amines and hydrazines. [ABSTRACT FROM AUTHOR]

Interactions between gold‐based materials and dioxygen (O2) have motivated researchers to understand reaction mechanisms for O2 activation by homo‐ and heterogeneous gold catalysts. In this work, gold(I) porphyrin dinuclear complexes were synthesized with a saddle‐distorted porphyrin ligand. The gold(I) porphyrin complexes showed unprecedented O2 activation in the presence of protic solvents to form gold(III) tetradentate porphyrin complexes. Mechanistic insights into the O2 activation by the gold(I) center were elucidated by spectroscopic measurements and theoretical calculations, revealing that dissociation of halides on the gold(I) center by alcohol solvents and hydrogen bonding of an N−H proton in the distorted porphyrin with dioxygen played important roles in establishing the unique reactivities of gold(I) complexes. [ABSTRACT FROM AUTHOR]

This review focuses on summarising the studies on transition metal catalysed transfer vinylation of alcohols using vinyl ethers and vinyl acetate as vinylating agents. Mercury, palladium, iridium and gold catalysts are discussed herein. Selected examples from publications and patents are given for the purpose of analysing functional group tolerance towards the methodology. In addition, mechanistic pathways are described. [ABSTRACT FROM AUTHOR]

This article introduces Professor Xiulin Fan as a new member of the editorial board of the Chinese Journal of Chemistry. Professor Fan's research focuses on the design of novel electrolytes and their impact on the electrochemical performance of next-generation lithium batteries. He has gained insights into the solvation structures of electrolytes and their relationship to the formation of the solid electrolyte interphase (SEI). Professor Fan has also discovered a new transport mechanism for lithium ions in electrolytes, enabling high energy density, fast charging, and a wide operating temperature range in lithium-ion batteries. [Extracted from the article]

Photocatalysis provides a versatile approach to redox activation of various organic substrates for synthetic applications. To broaden the scope of photoredox catalysis, developing catalysts with strong oxidizing or reducing power in the excited state is imperative. Catalysts that feature highly cathodic oxidation potentials and long lifetimes in their excited states are particularly in demand. In this research, we demonstrate the catalytic utility of two-coordinate Au(I) complex photocatalysts that exhibit an exclusive ligand-to-ligand charge-transfer (LLCT) transition in C–C cross-coupling reactions between N-heterocycles and (hetero)aryl halides, including redox-resistant (hetero)aryl chlorides. Our photocatalysis system can steer reactions under visible-light irradiation at a catalyst loading as low as 0.1 mol% and exhibits a broad substrate scope with high chemo- and regioselectivity. Our mechanistic investigations provide direct spectroscopic evidence for each step in the catalysis cycle and demonstrate that the LLCT-active Au(I) complex catalysts offer several benefits, including strong visible-light absorption, a 210 ns-long excited-state lifetime without short-lived components, and a 91% yield in the production of free-radical intermediates. Given the wide structural versatility of the proposed catalysts, we envision that our research will provide useful insights into the future utilization of the LLCT-active Au(I) complex for organic transformations. Developing photoredox catalysts with long-lived excited states that feature highly cathodic oxidation potentials is imperative. Here, the authors demonstrate the C–C cross-coupling catalytic utility of two-coordinate LLCT-active Au(I) complex photocatalysts with visible-light absorption and a 210 ns-long excited-state lifetime. [ABSTRACT FROM AUTHOR]

This study presents a surface engineering strategy utilizing electronic waste (e‐waste) to incorporate single‐atom catalysts on conjugated polymers. Employing a conjugated porphyrin polymeric photocatalyst, gold single‐atom‐site catalysts are successfully introduced using the acidic metal leachates from e‐waste, where metal speciation and composition are regulated during the metal loading processes. The resulting photocatalyst with gold single atoms demonstrates a remarkable hydrogen peroxide (H2O2) selectivity of up to 97.56%, yielding a pure H2O2 solution at 73.3 µm h−1 under white LED illumination. The produced H2O2 is activated to •OH radicals on the same polymer with mixed gold and iron atoms, enabling a photo‐Fenton reaction and the complete degradation of toxic microcystin‐LR within 10 min under visible light. This study highlights the universal applicability of the metal mining strategy in various photoreactions. It is believed that this discovery pioneers sustainable photocatalysis, allowing the tuning of reactivity and selectivity on photocatalytic surfaces using metal waste. [ABSTRACT FROM AUTHOR]

This article discusses a green and efficient method for synthesizing 2,3-dihydroquinazolinones, a class of heterocycles with biological and pharmacological activities. The authors propose using ball milling and montmorillonite K-10 as a catalyst under solvent-free conditions, which results in high yields and short reaction times. The montmorillonite K-10 catalyst is recyclable and the experimental section provides detailed information on the reaction conditions and characterization techniques used. The document also includes information on the synthesis and characterization of various compounds, with satisfactory results obtained for most of them. [Extracted from the article]

This study aimed to explore the impact of varying amounts of added Au (0.5 to 2 wt.%) and the structural characteristics of anatase TiO2 supports (nanoparticles (TP, SBET = 88 m2/g) and nanorods (TR, SBET = 105 m2/g)) on the catalytic efficiency of TiO2+Au catalysts in eliminating the herbicide glyphosate from aqueous solutions via the catalytic wet air oxidation (CWAO) process. The investigation was conducted using a continuous-flow trickle-bed reactor. Regardless of the TiO2 support and the amount of Au added, the addition of Au has a positive effect on the glyphosate degradation rate. Regarding the amount of Au added, the highest catalytic activity was observed with the TP + 1% Au catalyst, which had a higher Schottky barrier (SB) than the TP + 2% Au catalyst, which helped the charge carriers in the TiO2 conduction band to increase their reduction potential by preventing them from returning to the Au. The role of glyphosate degradation product adsorption on the catalyst surface is crucial for sustaining the long-term catalytic activity of the investigated TiO2+Au materials. This was particularly evident in the case of the TR + 1% Au catalyst, which had the highest glyphosate degradation rate at the beginning of the CWAO experiment, but its catalytic activity then decreased over time due to the adsorption of glyphosate degradation products, which was favoured by the presence of strong acidic sites. In addition, the TR + 1% Au solid had the smallest average Au particle size of all analyzed materials, which were more easily deactivated by the adsorption of glyphosate degradation products. The analysis of the degradation products of glyphosate shows that the oxidation of glyphosate in the liquid phase involves the rupture of C–P and C–N bonds, as amino-methyl-phosphonic acid (AMPA), glyoxylic acid and sarcosine were detected. [ABSTRACT FROM AUTHOR]

A novel smart catalyst was developed with amino‐modified thermo‐responsive poly(N‐isopropyl acrylamide) (PNIPAM) grafts on silica‐coated magnetic nanoparticles using the conventional free radical polymerization process. By this methodology, the polymer was successfully grafted mainly onto silica‐modified iron oxide nanoparticles (Fe3O4@Si). The PNIPAM‐grafted Fe3O4@Si was then subjected to ethylenediamine treatment to produce the amino‐functionalized support (Fe3O4@Si@PNIPAM‐NH2), which was subsequently modified with carboxyl functional groups by using EDTA (ethylenediaminetetraacetic acid) to create Fe3O4@Si@PNIPAM‐NH2‐EDTA. Au nanoparticles were then decorated on this support through its two amines and four carboxylates. Different methods were used to study this novel catalyst, including inductively coupled plasma, Fourier transport infrared spectroscopy, TGA, dynamic light scattering, SEM, energy‐dispersive X‐ray analysis, vibrating sample magnetometry, XRD and elemental CHN analysis. The reduction of several aryl‐nitro derivatives demonstrated a significant catalytic activity for the as‐synthesized gold catalyst (Fe3O4@Si@PNIPAM‐NH2‐EDTA‐Au). The Au catalyst can be successfully removed from the reaction components using a magnetic field and used again in eight successive reduction reactions without significant gold leaching and loss of catalytic activity. © 2024 Society of Industrial Chemistry. [ABSTRACT FROM AUTHOR]

The treatment of diabetic periodontitis poses a significant challenge due to the presence of local inflammation characterized by excessive glucose concentration, bacterial infection, and high oxidative stress. Herein, mesoporous silica nanoparticles (MSN) are embellished with gold nanoparticles (Au NPs) and loaded with manganese carbonyl to prepare a carbon monoxide (CO) enhanced multienzyme cooperative hybrid nanoplatform (MSN‐Au@CO). The Glucose‐like oxidase activity of Au NPs catalyzes the oxidation of glucose to hydrogen peroxide (H2O2) and gluconic acid，and then converts H2O2 to hydroxyl radicals (•OH) by peroxidase‐like activity to destroy bacteria. Moreover, CO production in response to H2O2, together with Au NPs exhibited a synergistic anti‐inflammatory effect in macrophages challenged by lipopolysaccharides. The underlying mechanism can be the induction of nuclear factor erythroid 2‐related factor 2 to reduce reactive oxygen species, and inhibition of nuclear factor kappa‐B signaling to diminish inflammatory response. Importantly, the antibacterial and anti‐inflammation effects of MSN‐Au@CO are validated in diabetic rats with ligature‐induced periodontitis by showing decreased periodontal bone loss with good biocompatibility. To summarize, MSN‐Au@CO is fabricate to utilize glucose‐activated cascade reaction to eliminate bacteria, and synergize with gas therapy to regulate the immune microenvironment, offering a potential direction for the treatment of diabetic periodontitis. [ABSTRACT FROM AUTHOR]

A series of cerium-based high-entropy oxide catalysts (the ratio of CeO2 and HEO is 1:1) was prepared by a solid-state reaction method, which exploit their unique structural and performance advantages. The Ce-HEO-T samples can achieve 100% toluene conversion rate above 328°C when they were used as catalysts directly. Subsequently, the Ce-HEO-500 exhibited the lowest temperature for toluene oxidation was used as a support to deposit different amounts of Au for a further performance improvement. Among all of prepared samples, Au/Ce-HEO-500 with a moderate content of Au (0.5 wt%) exhibited the lowest temperature for complete combustion of toluene (260°C), which decreased nearly 70°C compared with Ce-HEO-500 support. Moreover, it also showed excellent stability for 60 h with 98% toluene conversion rate. Most importantly, under the condition of 5 vol.% H2O vapour, the toluene conversion rate remained unchanged and even increased slightly compared with that in dry air, exhibiting excellent water resistance. Combined with the characterizations of XRD, SEM, TEM, BET, Raman, H2-TPR and XPS, it was found that the high dispersion of active Au NPs, the special high-entropy structure and the synergistic effect between Au and Ce, Co, Cu are the key factors when improving the catalytic performance in the Au/Ce-HEO-500 catalyst. [ABSTRACT FROM AUTHOR]

Growing hydrogen demand and progress in fuel cell technology contributed to renewed interest in water-gas shift (WGS) reaction. Supported gold catalysts attracted a special attention during the last three decades. Given the undisputed role of support nature in catalyst activity the purpose of this work was exploration of the effect of ceria amount (1, 3, and 5 wt%) and preparation approach as sol-gel (SG) or mechanochemical mixing (MM) to WGS activity of Au/TiO 2 catalyst. Thorough studies using textural measurements, X-ray fluorescence spectrometry, powder X-ray diffraction, transmission electron microscopy, UV–Vis diffuse reflectance, UV-Raman and X-ray photoelectron spectroscopy, electron paramagnetic resonance, and temperature-programmed reduction were carried out to explain the relationship among structure, electronic properties, and WGS performance. The catalysts showed a notably better performance as compared to Ce-free Au/TiO 2 counterpart by reaching a 90−93 % CO conversion at 180 °C vs. 75 % with unmodified sample. Formation of defective Ti 4 O 7 and Ce 11 O 20 phases occurred during sample preparation by SG. In addition, a distinct ceria phase was found in MM-prepared carriers to assist preferential gold deposition. All these structures contributed to improved WGS activity of the supported gold catalysts. Activity enhancement was related to Ce–Ti interactions and modification of structural and electronic properties that favor water dissociation. New insights into structure-to-function relationships of Au/Ce–TiO 2 catalysts for WGS reaction are provided. [Display omitted] • Effect of Ce doping in Au/TiO 2 and preparation route on WGS activity was explored. • Au/Ce-doped TiO 2 outperformed Au/TiO 2 by reaching a 93 % CO conversion at 180 °C. • Defective Ti 4 O 7 and Ce 11 O 20 phases occurred during sample preparation. • Modification of structural and electronic properties favored H 2 O dissociation. • Tuning physicochemical properties of TiO 2 enable higher WGS activity of Au catalysts. [ABSTRACT FROM AUTHOR]

In the quest to combat global warming, traditional thermal chemistry processes are giving way to selective photocatalysis, an eco-friendly approach that operates under milder conditions, using benign solvents like water. Benzaldehyde, a versatile compound with applications spanning agroindustry, pharmaceuticals, and cosmetics, serves as a fundamental building block for various fine chemicals. This study aims at enhancing benzaldehyde production sustainability by utilizing photooxidation of benzyl alcohol. Gold nanoparticle-based catalysts are renowned for their exceptional efficiency in oxidizing bio-based molecules. In this research, Au nanoparticles were anchored onto three distinct supports:  T i O 2 ,  Z r O 2 , and graphitic carbon nitride (g- C 3 N 4 ). The objective was to investigate the influence of the support material on the selective photocatalysis of benzyl alcohol. In the preparation of g- C 3 N 4 , three different precursors—melamine, urea, and a 50:50 mixture of both—were chosen to analyze their impact on catalyst performance. After 4 h of irradiation at 365 nm, operating under acidic conditions (pH = 2), the Au photocatalyst on graphitic carbon nitride support synthesized using urea precursor (Au@g- C 3 N 4 (u r e a) ) displayed the optimal balance between conversion (75%) and selectivity (85%). This formulation outperformed the benchmark Au@TiO2, which achieved a similar conversion rate (80%) but exhibited lower selectivity (55%). [ABSTRACT FROM AUTHOR]

[Display omitted] A herein proposed PdAu/Al 2 O 3 egg-shell catalyst for selective acetylene hydrogenation combines two factors to provide perfect performance: isolation of Pd 1 active sites by Au and an egg-shell distribution of the active phase across the catalyst pellets. The PdAu/Al 2 O 3 catalyst exhibits high acetylene hydrogenation activity at the level of Pd-catalysts and high intrinsic ethylene selectivity of Au-catalysts. [ABSTRACT FROM AUTHOR]

For energy harvesting with plasmonic photocatalysis, it is important to optimize geometrical arrangements of plasmonic nanomaterials, electron (or hole) acceptors, and co-catalysts so as to improve the charge separation efficiency and suppress charge recombination. Here, we employ a photocatalytic system with Au nanocubes on TiO2 and introduce MnO2 as an oxidation co-catalyst onto the nanocubes via site-selective oxidation based on plasmon-induced charge separation (PICS). However, it has been known that PbO2 is the only material that can be deposited onto Au nanomaterials through PICS with sufficient site-selectivity. Here we addressed this issue by introducing an indirect approach for MnO2 deposition via site-selective PbO2 deposition and subsequent galvanic replacement of PbO2 with MnO2. The indirect approach gave nanostructures with MnO2 introduced at around the top part, bottom part, or entire surface of the Au nanocubes on a TiO2 electrode. The activity of those plasmonic photocatalysts was strongly dependent on the location of MnO2. The key to improving the activity is to separate MnO2 from TiO2 to prevent recombination of the positive charges in MnO2 with the negative ones in TiO2. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal Chemical Communications, published by The Royal Society of Chemistry. It includes a feature article on the use of tetrazoles in constructing assemblies, as well as several communications on various topics such as electron-poor Au(III) trication, cold denaturation of DNA origami nanostructures, and optical discrimination of terpenes in citrus peels. The journal aims to connect the global chemistry community and publishes work from scientists at all career stages and countries. [Extracted from the article]

Utilizing sustainable electrocatalysis to upcycle glycerol (GLY; the by‐product of biodiesel) to lactic acid (LA; the key monomers for biodegradable polymer) is an efficient way to reduce the cost of biodiesel, which is also consistent with the waste‐to‐wealth principle. However, current research still suffers from issues of low LA selectivity (<80%), especially at high current density. Herein, we designed a cooperative catalyst by modifying BiOx nanolayers on gold nanoparticles (BiOx/Au), achieving high LA selectivity (82%) at high current density (226 mA cm−2 at 1.05 V vs. RHE), outperforming most of the reported works in the literature. We reveal that BiOx could promote the adsorption of the middle hydroxyl of GLY, which facilitates the formation of DHA and thus enables high LA selectivity. Moreover, the electron‐deficient Au in BiOx/Au is responsible for the enhanced current density, which is more beneficial to generate reactive oxygen species (OH*). To further reveal the application potential of this electrocatalytic strategy, we realized that the conversion of crude GLY extracted from cooking oil to LA coupled with H2 production using a membrane‐free flow electrolyzer, demonstrating a sustainable fashion to convert biodiesel waste into high value‐added product and H2 fuel. [ABSTRACT FROM AUTHOR]

Gold complexes, because of their unique carbophilic nature, have evolved as efficient catalysts for catalyzing various functionalization reactions of C–C multiple bonds. However, the realization of enantioselective transformations via gold catalysis remains challenging due to the geometrical constraints and coordination behaviors of gold complexes. In this context, merged gold/organocatalysis has emerged as one of the intriguing strategies to achieve enantioselective transformations which could not be possible by using a single catalytic system. Historically, in 2009, this field started with the merging of gold with axially chiral Brønsted acids and chiral amines to achieve enantioselective transformations. Since then, based on the unique reactivity profiles offered by each catalyst, several reports utilizing gold in conjunction with various chiral organocatalysts such as amines, Brønsted acids, N-heterocyclic carbenes, hydrogen-bonding and phosphine catalysts have been documented in the literature. This article demonstrates an up-to-date development in this field, especially focusing on the mechanistic interplay of gold catalysts with chiral organocatalysts. [ABSTRACT FROM AUTHOR]

Conventional spherical nucleic acid enzymes (SNAzymes), made with gold nanoparticle (AuNPs) cores and DNA shells, are widely applied in bioanalysis owing to their excellent physicochemical properties. Albeit important, the crowded catalytic units (such as G-quadruplex, G4) on the limited AuNPs surface inevitably influence their catalytic activities. Herin, a hybridization chain reaction (HCR) is employed as a means to expand the quantity and spaces of G4 enzymes for their catalytic ability enhancement. Through systematic investigations, we found that when an incomplete G4 sequence was linked at the sticky ends of the hairpins with split modes (3:1 and 2:2), this would significantly decrease the HCR hybridization capability due to increased steric hindrance. In contrast, the HCR hybridization capability was remarkably enhanced after the complete G4 sequence was directly modified at the non-sticky end of the hairpins, ascribed to the steric hindrance avoided. Accordingly, the improved SNAzymes using HCR were applied for the determination of AFB1 in food samples as a proof-of-concept, which exhibited outstanding performance (detection limit, 0.08 ng/mL). Importantly, our strategy provided a new insight for the catalytic activity improvement in SNAzymes using G4 as a signaling molecule. [ABSTRACT FROM AUTHOR]

In this study, we systematically investigated the effect of single-atom gold (Au) loaded on ZnIn2S4 nanosheets on the photocatalytic reduction of carbon dioxide (CO2). Utilizing a photodeposition method, we successfully dispersed single-atom Au uniformly on the surface of ZnIn2S4 nanosheets. Under simulated sunlight irradiation, the Au-loaded catalyst demonstrated a higher yield and selectivity in the CO2 reduction reaction compared to the pure ZnIn2S4 nanosheets. Surface photovoltage testing revealed that the addition of Au significantly enhanced the separation efficiency of photo-generated charge carriers, thereby improving the photocatalytic efficiency. Density functional theory calculations indicated that the loading of single-atom Au reduced the reaction energy barrier from CO2 to CO, enhancing the selectivity of photocatalytic CO2 reduction. This research not only developed an efficient catalyst for CO2 reduction but also provided deep insights into the mechanism of single-atom catalysts in the photocatalytic CO2 reduction process through extensive experimental and theoretical analysis. [ABSTRACT FROM AUTHOR]

An efficient stereoselective synthesis of cis-2,6-disubstituted tetrahydropyrans 14a–c has been achieved via gold-catalyzed Meyer–Schuster rearrangement/hydration/oxa-Michael addition sequence from bis-propargylic alcohols 13a–c. The reaction of 13a proceeds via 2,6-disubstituted tetrahydropyran 14′a as an intermediate. [ABSTRACT FROM AUTHOR]

We have developed a new liquid‐phase noncatalytic selective oxidation of polyhydric alcohols such as glycerol. This method involves the use of a nonthermal atmospheric‐pressure plasma instead of precious‐metal catalysts. We found that noncatalytic selective oxidation of glycerol achieved a conversion comparable to that achieved by gold‐catalyzed oxidation, and the desired glyceric acid, which is a pharmaceutical raw material, was obtained. When the solution pH was changed from strongly alkaline to neutral, the main reaction switched from the one that occurs in the presence of gold catalysts to the one that occurs in the presence of platinum catalysts. These results suggest that the reactive oxygen species generated by nonthermal atmospheric‐pressure plasma irradiation vary depending on the solution pH. [ABSTRACT FROM AUTHOR]

The surface properties of oxidic supports and their interaction with the supported metals play critical roles in governing the catalytic activities of oxide‐supported metal catalysts. When metals are supported on reducible oxides, dynamic surface reconstruction phenomena, including strong metal–support interaction (SMSI) and oxygen vacancy formation, complicate the determination of the structural–functional relationship at the active sites. Here, we performed a systematic investigation of the dynamic behavior of Au nanocatalysts supported on flame‐synthesized TiO2, which takes predominantly a rutile phase, using CO oxidation above room temperature as a probe reaction. Our analysis conclusively elucidated a negative correlation between the catalytic activity of Au/TiO2 and the oxygen vacancy at the Au/TiO2 interface. Although the reversible formation and retracting of SMSI overlayers have been ubiquitously observed on Au/TiO2 samples, the catalytic consequence of SMSI remains inconclusive. Density functional theory suggests that the electron transfer from TiO2 to Au is correlated to the presence of the interfacial oxygen vacancies, retarding the catalytic activation of CO oxidation. [ABSTRACT FROM AUTHOR]

Uric acid (UA) is an important biomarker, as a high concentration in blood can lead to gout and further renal syndrome. Although several point-of-care testing (POCT) devices have been reported to detect UA, there are some limitations such as the requirement for uricase and the complicated pretreatment of serum/plasma samples, which restricts their use at home or in undeveloped areas. In this work, we developed an approach by applying Zn2+ to precipitate proteins and cells in whole blood to avoid interference with the chromogenic reaction. We used carboxymethylcellulose (CMC) to immobilize tetramethylbenzidine (TMB) on a nitrocellulose membrane for colorimetric detection. Using the oxidization properties of H2O2, which turns TMB into oxidized tetramethylbenzidine (TMBox) in the presence of catalyst gold nanoparticles (AuNPs), we successfully constructed an enzyme-free paper-based POCT device using the reduction reaction of UA and TMBox for simple, speedy, and cheap colorimetric detection of UA, achieving a detection time of 8 min, a linear range of 0–150 μg/mL, and an LOD of 25.79 μg/mL. The UA concentration in whole blood samples was further measured and correlated well with the clinical value (R2 = 0.8212). Thus, the proposed assay has the potential for POCT diagnosis, monitoring, and prognosis of diseases related to UA. By applying Zn2+ reagent to precipitate proteins and cells in whole blood and the reduction reaction of UA, an enzyme-free paper-based POCT assay was established. [ABSTRACT FROM AUTHOR]

As heterogeneous catalysts, nanoclusters have been extensively investigated because of their exceptional catalytic performance. In this work, we propose an electrostatic attraction strategy to immobilize atomically precise positively charged [Au52Cu72(SR)55]+ (denoted as Au52Cu72(SR)55) nanoclusters supported onto negatively charged SBA‐15. As expected, the Au52Cu72(SR)55/SBA‐15 catalysts display outstanding activity for driving the benzyl azide‐phenylacetylene cycloaddition reaction (called as click reaction). In comparison to Au11/SBA‐15 and Cu13/SBA‐15 catalysts, the bimetallic Au52Cu72(SR)55/SBA‐15 catalysts exhibit the highest catalytic activity for click reaction. Moreover, to explore the effect of ligands on the catalytic performance of Au52Cu72(SR)55/SBA‐15 catalysts, Au52Cu72(SR)55/SBA‐15‐X (X is the heat treatment temperature, X=120, 250, 300) catalysts are obtained by calcining at different temperatures. Compared with Au52Cu72(SR)55/SBA‐15‐X (X=120, 250, 300), the uncalcined Au52Cu72(SR)55/SBA‐15 catalysts show the best recyclability for click reaction. The structural integrity of the Au52Cu72(SR)55 nanoclusters is a key factor contributing to their exceptional cyclic performance. This work will be valuable for designing an ideal ligand‐protected clusters‐based catalysts with superior performance for organic reactions. [ABSTRACT FROM AUTHOR]

The use of gold nanoparticles (Au NPs) as catalysts has gained widespread attention in various reactions due to their high activity and selectivity under mild reaction conditions. However, one major challenge in utilizing these catalysts is their tendency to aggregate, leading to catalyst deactivation and hindering their amplification and industrial application. To overcome this issue, herein, we used a method by coating the surface of Au NPs with a thin layer of SiO2, which resulted in the formation of a superior catalyst denoted as Au@SiO2/ZA. Characterization studies revealed that the SiO2 layer is coated on the surface of Au NPs and effectively prevents the aggregation and growth of the gold particles during the reaction process, which makes the catalyst display excellent stability in furfural (FF) oxidative esterification to methyl furoate (MF). Moreover, the stabilization strategy is not limited to SiO2 alone. It can also be extended to other oxides such as ZrO2, CeO2, and TiO2. We believe this work will provide a good reference for the design and development of an efficient and stable gold catalyst for the oxidative esterification reaction. [ABSTRACT FROM AUTHOR]

Gold nanoparticles have shown great potential for heterogeneous catalysis. Herein, we show that the catalytic efficiency of gold nanorods (Au NRs) depends sensitively on their aspect ratio. The high-energy side facets of Au NRs play a crucial role in their catalytic efficiency. We have synthesized Au NRs of three different aspect ratios using a modified seed-mediated method. The aspect ratio of Au NRs increased from 2.3 to 4.6 and then to 5.4 with the addition of different concentrations of HNO3 in the growth solution. The synthesized Au NRs with different aspect ratios were tested for their catalytic activity towards the reduction of various organic pollutants such as 4-nitrophenol (4-NP), methylene blue (MB), and methyl orange (MO). It was found that for the same gold content, nanorods with a larger surface area of the high-energy side facets, irrespective of the overall surface area, were more effective catalysts in all cases. [ABSTRACT FROM AUTHOR]

One-pot synthesis of (E)-5-[bromo(phenyl)methylene]-4-phenyl-2-(p-tolyl)-4,5-dihydrooxazole (9) from propargylic alcohol 5 and p-toluamide (6) was achieved via gold(III)-catalyzed propargylic substitution, followed by gold(III)-catalyzed bromocyclization. The structure of 9 was confirmed by an X-ray crystallographic analysis. [ABSTRACT FROM AUTHOR]

The characterization and identification of the dynamics of cluster catalysis are crucial to unraveling the origin of catalytic activity. However, the dynamical catalytic effects during the reaction process remain unclear. Herein, we investigate the dynamic coupling effect of elementary reactions with the structural fluctuations of sub-nanometer Au clusters with different sizes using ab initio molecular dynamics and the free energy calculation method. It was found that the adsorption-induced solid-to-liquid phase transitions of the cluster catalysts give rise to abnormal entropy increase, facilitating the proceeding of reaction, and this phase transition catalysis exists in a range of clusters with different sizes. Moreover, clusters with different sizes show different transition temperatures, resulting in a non-trivial size effect. These results unveil the dynamic effect of catalysts and help understand cluster catalysis to design better catalysts rationally. [ABSTRACT FROM AUTHOR]

Understanding the factors that affect the reactivity of gold nanoparticles (Au NPs) in the catalytic oxidation of organic compounds remains an important issue. Of particular significance is tuning the effect of metal‐support interaction toward improving the catalytic performance of Au NPs. The main goal of this study is to provide new insight into the role of the amino‐organosilane (APMS) modifier, used for anchoring of gold species on ZnO support, in controlling the reactivity of Au NPs in H2O2 activation and the subsequent catalytic oxidation of benzyl alcohol. This study reveals that APMS modifier weakens the electronic interaction between ZnO and Au NPs, leading to a lower catalase‐like activity toward H2O2 in comparison to that observed for modifier‐free gold catalyst of similar size of nanoparticles. As a result, a slower rate of oxygen evolution resulted in higher activity in the oxidation of benzyl alcohol and enabled more efficient utilization of H2O2 under base‐free conditions. No radical species were formed during the oxidation reaction, and molecular oxygen formed in situ in the reaction medium was the primary oxidant responsible for the catalytic conversion of benzyl alcohol. [ABSTRACT FROM AUTHOR]

To tackle the obstacles related to tumor targeting and overcome the limitations of single treatment models, we have developed a nanoplatform that is both tumor-targeted and enzyme-responsive. This nanoplatform integrates photothermal gold nanorods (AuNRs) and protein drugs into a single system. This nanosystem, known as AuNRs@HA-mPEG-Deta-LA, was fabricated by modifying gold nanorods (AuNRs) with a polymeric ligand called hyaluronic acid-grafted-(mPEG/diethylenetriamine-conjugated-lipoic acid). The purpose of this fabrication was to load cytochrome c (CC) and utilize it for the synergetic protein–photothermal therapy of cancer. The resulting nanoplatform exhibited a high efficiency in loading proteins and demonstrated excellent stability in different biological environments. Additionally, CC-loaded AuNRs@HA-mPEG-Deta-LA not only enabled localized hyperthermia for photothermal therapy (PTT) with laser irradiation but also facilitated the release of CC under the action of hyaluronidase, an enzyme known to be overexpressed in tumor cells. The confocal imaging results demonstrated that the presence of a specific polymeric ligand on this nanoparticle enhances the internalization of CD44-positive cancer cells, accelerates endo/lysosomal escape, and facilitates the controlled release of CC within the cells. Furthermore, the results of the MTT assay also showed that AuNRs@HA-mPEG-Deta-LA as a protein nanocarrier demonstrated excellent biocompatibility. Importantly, this synergistic therapeutic strategy effectively induced apoptosis in A549 cancer cells by increasing the intracellular concentration of CC and utilizing the photothermal conversion of AuNRs, which was observed to be more effective compared to using only protein therapy or PTT. Therefore, this study showcased a nanoplatform based on AuNRs that has great potential for tumor-targeted protein delivery in combination with PTT in cancer treatment. [ABSTRACT FROM AUTHOR]

Owing to their remarkable properties, gold nanoparticles are applied in diverse fields, including catalysis, electronics, energy conversion and sensors. However, for catalytic applications of colloidal gold nanoparticles, the trade-off between their reactivity and stability is a significant concern. Here we report a universal approach for preparing stable and reactive colloidal small (~3 nm) gold nanoparticles by using multi-dentate polyoxometalates as protecting agents in non-polar solvents. These nanoparticles exhibit exceptional stability even under conditions of high concentration, long-term storage, heating and addition of bases. Moreover, they display excellent catalytic performance in various oxidation reactions of organic substrates using molecular oxygen as the sole oxidant. Our findings highlight the ability of inorganic multi-dentate ligands with structural stability and robust steric and electronic effects to confer stability and reactivity upon gold nanoparticles. This approach can be extended to prepare metal nanoparticles other than gold, enabling the design of novel nanomaterials with promising applications. For catalytic nanoparticles there is often a trade-off between stability and activity. Here the authors report a route to ultra-stable and catalytically active colloidal small (~3 nm) gold nanoparticles using multi-dentate polyoxometalates as protecting agents in nonpolar solvents. [ABSTRACT FROM AUTHOR]