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[Display omitted] • The Au NPs are homogeneously embedded in nanogels by in-situ reduction. • The LSPR effect of the Au NPs improves the photothermal conversion capability. • The cotton fabrics cross-linked with hybrid nanogels present excellent anti-bacteria and thermal regulation via photothermal conversion. Enhanced anti-bacterial properties and thermal regulation are realized in cotton fabrics cross-linked with hybrid poly(di(ethylene glycol) methyl ether methacrylate- co -oligo(ethylene glycol) methyl ether methacrylate- co -ethylene glycol methacrylate) nanogels containing gold nanoparticles (Au NPs), denoted as hybrid P(MA- co -MA 300 - co -EGMA)/Au nanogels. Pure P(MA- co -MA 300 - co -EGMA) nanogels are synthesized by emulsion polymerization as carriers and then embedded with Au NPs via in-situ reduction. By applying 1,2,3,4-butanetetracarboxylic acid as a cross-linker and changing the amount of hybrid P(MA- co -MA 300 - co -EGMA)/Au nanogels in solution, the weight gain ratios of hybrid nanogels on cotton fabrics are set as 10 % (CHN-10) and 20 % (CHN-20). Due to the densely packed structure of the hybrid nanogels on the surface, the localized surface plasmon resonance (LSPR) effect of the Au NPs improves the photothermal conversion capability and converts the absorbed light energy into thermal energy. Simply illuminating with visible light, the surface temperature of CHN-20 pronouncedly increases from 20.4 to 43.0 °C in 50 s. The increased local temperature induces the denaturation of protein and the death of bacteria on the surface. Thus, an illumination with visible light for 2 h results in an anti-bacterial rate for S. aureus of 100 % for CHN-20. Additionally, it presents an excellent thermal regulation capability via photothermal conversion and can be used for continuously maintaining human body temperature in cold areas. Because no additional chemical agents and external power source are required for the anti-bacterial properties and thermal regulation, the obtained cotton fabrics cross-linked with hybrid P(MA- co -MA 300 - co -EGMA)/Au nanogels are eco-friendly and suitable for smart textiles in daily wear. [ABSTRACT FROM AUTHOR]

A simple and rapid colorimetric detection strategy, based on hydrogen bond identification of 6-thioguanine (6-TG) functionalized Au nanoparticles (AuNPs), is proposed for highly selective and sensitive determination of kanamycin (KA). In this strategy, the hydrogen bond interaction between 6-TG and kanamycin induces AuNPs to agglomerate, with a consequent color change of AuNPs from wine red to purple or even blue. The kanamycin concentrations can be quantified by employing UV–vis spectrophotometer. The results display that kanamycin concentrations (0.005 to 18 µM) are linearly related to A620/A520 (the absorbance ratio of 620 nm and 520 nm) with a LOD of 1.8 nM and a LOQ of 5.9 nM (S/N = 3). This strategy also reveals a high degree of selectivity among a series of common interfering species. Moreover, the strategy can be employed to detect trace amounts of kanamycin in real-life samples, and it shows satisfying results compared with high performance liquid chromatography. In general, this developed strategy is facile and inexpensive without the need for complex processing procedures and expensive instruments. In addition, this work may further exploit detection strategies for other organic contaminants, as well as make a strong contribution to the development of the colorimetric method. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) were synthesized using dragon fruit peel extract (DFE) as a reducing agent and stabilizer. Confirmation of AuNP formation included the distinct red coloration of the solution and the appearance of surface plasmon resonance (SPR) peak at approximately 530 nm in the UV–visible spectrum. Synthesis conditions, such as solution pH, HAuCl4 concentration, and DFE concentration, were varied to observe their influence on the AuNPs. Characterization using TEM revealed well-dispersed, nearly spherical particles with diameters ranging from 6 to 20 nm and a mean diameter of 12 ± 3 nm. XRD and SAED patterns confirmed the face-centered cubic (FCC) crystal structure. FTIR analysis highlighted the role of DFE functionalities in reducing and stabilizing the AuNPs. Zeta potential analysis indicated a negative surface charge on DFE@AuNPs, ensuring colloidal stability. The antioxidant activity of DFE@AuNPs was assessed using the ABTS assay, demonstrating comparable efficacy to ascorbic acid as a standard. Furthermore, the catalytic activity of the nanoparticles was evaluated through the NaBH4-assisted reduction of malachite green (MG) dye, with over 90% reduction observed within 24 min, following pseudo-first order kinetics with the rate constant of 0.069 ± 0.011 min−1 obtained from exponential fit. [ABSTRACT FROM AUTHOR]

N-Doped highly ordered mesoporous carbon (N-OMC) material was synthesized by impregnation of egg-yolk biomass into the SBA-15 template, followed by carbonization at 700 °C under an atmosphere of N2, and removal of the SBA-15 silica moiety with an alkaline aqueous solution under heating conditions. Au nanoparticles were decorated on the surface of the N-OMC material by chemical reduction of NaAuCl3 using NaBH4 in the presence of N-OMC. The synthesized Au@N-OMC was characterized by XRD, SEM, TEM, XPS, BET and EDS, which showed the successful decoration of Au nanoparticles on the surface of mesoporous carbon. Au@N-OMC showed high catalytic activity in the remediation of nitroaromatic pollutants from wastewater by reduction to the corresponding aniline derivatives. The kinetics of the Au@N-OMC-catalyzed reduction of 4-nitrophenol was investigated, which showed that the reduction in the presence of excess amount of NaBH4 reductant, followed pseud-first-order kinetics. Three methods were carried out to investigate the reusability of the Au@N-OMC catalyst, which showed that the recycled catalyst could be reused several times without significant changes in catalytic activity. The leaching test was also performed by separating the Au@N-OMC catalyst at the half time of the reaction, revealing the heterogeneity of the catalyst. [ABSTRACT FROM AUTHOR]

Attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) is a powerful method for probing interfacial chemical processes. However, SEIRAS-active nanostructured metallic thin films for the in situ analysis of electrochemical phenomena are often unstable under biased aqueous conditions. In this work, we present a surface-enhancing structure based on etched black Si internal reflection elements with Au-coatings for in situ electrochemical ATR-SEIRAS. Using electrochemical potential-dependent adsorption and desorption of 4-methoxypyridine on Au, we demonstrate that black Si-based substrates offer advantages over commonly used structures, such as electroless-deposited Au on Si and electrodeposited Au on ITO-coated Si, due to the combination of high stability, sensitivity, and conductivity. These characteristics are especially valuable for time-resolved measurements where stable substrates are required over extended times. Furthermore, the low sheet resistance of Au layers on black Si reduces the RC time constant of the electrochemical cell, enabling a significantly higher time resolution compared to that of traditional substrates. Thus, we employ black Si-based substrates in conjunction with rapid- and step-scan Fourier transform infrared (FTIR) spectroscopy to investigate the adsorption and desorption kinetics of 4-methoxypyridine during in situ electrochemical potential steps. Adsorption is shown to be diffusion-limited, which allows for the determination of the mean molecular area in a fully established monolayer. Moreover, no significant changes in the peak ratios of vibrational modes with different orientations relative to the molecular axis are observed, suggesting a single adsorption mode and no alteration of the average molecular orientation during the adsorption process. Overall, this study highlights the enhanced performance of black Si-based substrates for both steady-state and time-resolved in situ electrochemical ATR-SEIRAS, providing a powerful platform for kinetic and mechanistic investigations of electrochemical interfaces.

Au/Ni nanotubes were fabricated on carbon papers through depositing Au nanoparticles on Ni nanotubes to construct nitrite sensors. The structure and constituent characterisation of Au/Ni-60s NTs demonstrated the homogeneous distribution of Au nanoparticles on the Ni nanotubes. Due to the synergy between Ni nanotubes and Au nanoparticles, highly improved nitrite sensing performance was achieved on Au/Ni-60s NTs, which presented a very wide linear range for nitrite detection. Two linear segments have been obtained in the range of 0.4–40000 µM and 40–130 mM with the detection limit of 0.13 μM. The sensitivity of 707.14 µA·mM−1·cm−2 in lower region and 339.53 µA·mM−1·cm−2 in higher region was achieved. Furthermore, the obtained Au/Ni-60s NTs displayed good selectivity and high reliability for nitrite detection in real samples such as milk and peach juice. This investigation may provide a useful route and reference to construct tubular structures for efficient nitrite detection. [ABSTRACT FROM AUTHOR]

3D surface‐enhanced Raman scattering (SERS) platforms with multi‐dimensional hotspots and better tolerance to laser misfocus show great potential for the rapid detection of trace fentanyl. However, the complex fabrication process of 3D fine structures limits the wide‐ranging application of the SERS technique. Herein, a 3D SERS‐active platform is fabricated utilizing a scalable and cost‐effective strategy that involves the electroless deposition of dense Au nanoparticles on natural butterfly wing scales (b‐wings@Au). The resultant b‐wings@Au proves to be sensitive and reliable, with a lower limit of detection of 4× 10−12 m and an enhancement factor (EFexp) of 1.74 × 108 for fentanyl. Furthermore, it exhibits excellent reproducibility, as evidenced by a relative standard deviation of less than 5%, and also demonstrates outstanding stability. The obtained high EFexp is due to the combined effects of the electromagnetic mechanism, involving the enhanced electromagnetic field generated by 3D periodic hotspots, and the chemical mechanism, involving the charge transfer from fentanyl to Au surface. Additionally, the as‐prepared 3D substrate realizes the trace detection of nine fentanyl analogs. This study provides new ideas for the controllable construction of sensitive SERS platforms for drug detection, ultimately advancing the fields of 3D substrates in booming SERS‐based technologies. [ABSTRACT FROM AUTHOR]

An optimised synthesis of the metal‐organic framework (MOF) UiO‐66(Ce) is reported using a modulator‐free route, yielding ~5 g of material with high crystallinity and 22 % ligand defect. Two methods are developed for loading gold nanoparticles onto the MOF. The first uses a double‐solvent method to introduce HAuCl4 onto UiO‐66(Ce), followed by reduction under 5 % H2 in N2, while the second is a novel one‐pot method where HAuCl4 is added to the synthesis mixture, forming Au nanoparticles within the pores of the UiO‐66(Ce) during crystallisation. Analysis using powder X‐ray diffraction (PXRD), nitrogen adsorption isotherms, transmission electron microscopy and small‐angle X‐ray scattering (SAXS) reveals that the two‐step double‐solvent method yields gold crystallites on the external surface of the MOF particles that are visible by PXRD. In contrast, the one‐pot method forms smaller gold crystallites, with a distribution of sizes centred on ~4 nm diameter as seen by SAXS, with evidence from PXRD for the smallest particles being present within the MOF structure. The Au‐loaded UiO‐66(Ce) materials are evaluated for the catalytic oxidation of vanillyl alcohol to vanillin at 60 °C. Our findings indicate that incorporating Au nanoparticles via the one‐pot synthesis method, enhances redox activity, achieving 43 % conversion and 90 % selectivity towards vanillin. [ABSTRACT FROM AUTHOR]

Photocatalytic CH4 oxidation to ethanol with high selectivity is attractive but substantially challenging. The activation of inert C−H bonds at ambient conditions requires highly reactive oxygen species like hydroxyl radicals (⋅OH), while the presence of those oxidative species also facilitates fast formation of C1 products, instead of the kinetically sluggish C−C coupling to produce ethanol. Herein, we developed a BiVO4 photocatalyst with surface functionalization of Au nanoparticles (BiVO4@Au), which not only enables photogeneration of ⋅OH to activate CH4 into ⋅CH3, but also in situ consumes those ⋅OH species to retard their further attack on ⋅CH3, resulting in an enhanced ⋅CH3/⋅OH ratio and facilitating C−C coupling toward ethanol. The ⋅CH3/⋅OH ratio is further improved by transporting CH4 via a gas‐diffusion layer to the photocatalytic interface, leading to even higher ethanol selectivity and production rates. At ambient conditions and without photosensitizers or sacrificial agents, the BiVO4@Au photocatalyst exhibited an outstanding CH4‐to‐ethanol conversion performance, including a peak ethanol yield of 680 μmol ⋅ g−1 ⋅ h−1, a high selectivity of 86 %, and a stable photoconversion of >100 h, substantially exceeding most of the previous reports. Our work suggests an attractive approach of in situ generation and modulation of the ⋅OH levels for photocatalytic CH4 conversion toward multi‐carbon products. [ABSTRACT FROM AUTHOR]

Bromelain (Br) is a proteolytic enzyme with various pharmacological properties, such as antibacterial, antioxidant, anti-inflammatory, anticancer, and anti-angiogenic properties. However, due to its low solubility and bioavailability, its absorption is low, so a delivery mechanism is needed to achieve the desired therapeutic effects. Bromelain was chemically synthesized and loaded onto gold nanoparticles (AuNPs). Different methods and techniques were used for detection and characterization, including color-change detection, UV spectroscopy, XRD, SEM, TEM, and FTIR. The in vitro antioxidant activity was detected using DPPH assays, and the wound-healing activity was investigated in mice. The current study revealed that the formulated AuNPs-Br showed effective antioxidant activity and the strongest wound-healing properties, as demonstrated by histopathological and in vivo studies, and showed anti-angiogenic effects. [ABSTRACT FROM AUTHOR]

[Display omitted] Regulating the electron structure and precise loading sites of metal-active sites within the highly conjugated and porous covalent-triazine frameworks (CTFs) is essential to promoting the nitrogen reduction reaction (NRR) performance for electrocatalytic ammonia (NH 3) synthesis under ambient conditions. Herein, experimental method and density functional theory (DFT) calculations were conducted to deeply probe the effect on NRR of the modulation of modulating the electron structure and the loading site of gold nanoparticles (Au NPs) in a two-dimensional (2D) CTF. 2D CTF synthesized using melem and hexaketocyclohexane octahydrate as building blocks (denoted as M−HCO−CTF) served as a robust scaffold for loading Au NPs to form an M−HCO−CTF@AuNP hybrid. DFT results uncovered that well-defined Au sites with tunable local structure were the active site for driving the NRR, which can significantly suppress the conversion of H+ into *H adsorption and enhance the nitrogen (N 2) adsorption/activation. The overlapped Au (3 d) and *N 2 (2 p) orbitals lowered the free energy of the rate-determining step to form *NNH, thereby accelerating the NRR. The M−HCO−CTF@AuNPs electrocatalyst exhibited a large NH 3 yield rate of 66.3 μg h−1 mg−1 cat. and a high Faraday efficiency of 31.4 % at − 0.2 V versus reversible hydrogen electrode in 0.1 M HCl, superior to most reported CTF-based ones. This work can provide deep insights into the modulation of the electron structure of metal atoms within a porous organic framework for artificial NH 3 synthesis through NRR. [ABSTRACT FROM AUTHOR]