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Multifunctional targeted drug delivery systems have been explored as a novel cancer treatment strategy to overcome limitations of traditional chemotherapy. The combination of photodynamic therapy and chemotherapy has been shown to enhance efficacy, but the phototoxicity of traditional photosensitizers is a challenge. In this study, we prepared a multi-sensitive composite hydrogel containing gold nanoclusters (Au NCs) and the temperature-sensitive antitumor drug 5-fluorourac il (5-FU) using carboxymethyl cellulose (Carr) as a dual-functional template. Au NCs were synthesized using sodium borohydride as a reducing agent and potassium as a promoter. The resulting Au NCs were embedded in the Carr hydrogel, which was then conjugated with lactobionic acid (LA) as a targeting ligand. The resulting Au NCs/5-FU@Carr-LA composite hydrogel was used for synergistic photodynamic therapy (PDT), photothermal therapy (PTT), and chemotherapy. Au NCs/5-FU@Carr-LA releases the drug faster at pH 5.0 due to the acid sensitivity of the Carr polymer chain. In addition, at 50 °C, the release rate of Au NCs/5-FU@Carr-LA is 78.2%, indicating that the higher temperature generated by the photothermal effect is conducive to the degradation of Carr polymer chains. The Carr hydrogel stabilized the Au NCs and acted as a matrix for drug loading, and the LA ligand facilitated targeted delivery to tumor cells. The composite hydrogel exhibited excellent biocompatibility and synergistic antitumor efficacy, as demonstrated by in vitro and in vivo experiments. In addition, the hydrogel had thermal imaging capabilities, making it a promising multifunctional platform for targeted cancer therapy. [ABSTRACT FROM AUTHOR]

Gold nanoclusters (AuNCs) possess weak intrinsic fluorescence, limiting their sensitivity in biosensing applications. This study addresses these limitations by developing a spatially confined dual-emission nanoprobe composed of silicon nanoparticles (SiNPs) and AuNCs. This amplified and stabilized fluorescence mechanism overcomes the limitations associated with using AuNCs alone, achieving superior sensitivity in the sensing platform. The nanoprobe was successfully employed for ratiometric detection of bleomycin (BLM) in serum samples, operating at an excitation wavelength of 365 nm, with emission wavelengths at 480 nm and 580 nm. The analytical performance of the system is distinguished by a linear detection range of 0–3.5 μM, an impressive limit of detection (LOD) of 35.27 nM, and exceptional recoveries ranging from 96.80 to 105.9%. This innovative approach significantly enhances the applicability and reliability of AuNC-based biosensing in complex biological media, highlighting its superior analytical capabilities. [ABSTRACT FROM AUTHOR]

Metal nanoclusters with aggregation‐induced emission (AIE) characteristics are potential nanomaterial candidates for a wide array of advanced optical applications. In this study, a novel self‐assembly enhanced AIE strategy utilizing 6‐thioguanine (TG)‐protected gold nanoclusters (AuNCs) is fabricated with dual‐stimuli responsive modes of excitation wavelength‐dependent (Ex‐De) emission and mechanochromic properties. The sheetlike structures of AuNCs self‐assembly (AuNC sheets) with typical AIE characteristics are generated in bad solvent owing to the intermolecular hydrogen‐bonds interaction among guanine‐rich moieties of TG ligand. Interestingly, the maximum emission peaks of AuNC sheets are red‐shifted with the increased excitation wavelengths, indicating Ex‐De emission behavior. This phenomenon enables the achievement of wide‐range tunable photoluminescence (PL). In addition, the emission peak of AuNC sheets powders before and after grinding displays the bathochromic shift of 110 nm. The "off–on" switch of Ex‐De emission behavior in AuNC sheets can be manipulated by changing mechanical pressure. It is speculated that the tunable PL behavior of AuNC sheets originates from multiple excited states due to the existence of different Au(I)···Au(I) distances. The self‐assembly‐driven AIE strategy of AuNCs with stimuli‐responsive allochroic modes will facilitate the recording of rewritable information, opening up a new avenue for high‐throughput and multi‐dimensional optical security. [ABSTRACT FROM AUTHOR]

Gold nanoclusters (AuNCs) have great potential to enhance tumor radiotherapy. However, their tumor accumulation efficiency is relatively low due to their ultrasmall size. In this study, an acid-responsive tumor targeting strategy is proposed by introducing l-cystine onto glutathione-coated AuNCs (l-Cys/GSH@AuNCs). l-Cys/GSH@AuNCs are able to swiftly respond to acid conditions to assembly into large clusters and aggregate in lysosomes upon internalization by tumor cells, leading to increased accumulation in cancer cells. Moreover, metal radioisotope 89Zr and 68Ga could be doped into AuNCs with high efficiency and stability. PET imaging of tumor-bearing mice reveals that radiolabeled l-Cys/GSH@AuNCs are primarily eliminated via the renal system but could respond to tumor acid microenvironment to accumulate in tumor high efficiently and remain in tumors for a long time period. As a result, radiotherapy in combination with l-Cys/GSH@AuNCs completely suppresses tumor growth. Our study paves a way for AuNCs to enhance tumor radiotherapy. [ABSTRACT FROM AUTHOR]

Gold nanoclusters (AuNCs) are a class of novel luminescent nanomaterials that exhibit unique properties of ultra-small size, featuring strong anti-photo-bleaching ability, substantial Stokes shift, good biocompatibility, and low toxicity. Various biomolecules have been developed as templates or ligands to protect AuNCs with enhanced stability and luminescent properties for biomedical applications. In this review, the synthesis of AuNCs based on biomolecules including amino acids, peptides, proteins and DNA are summarized. Owing to the advantages of biomolecule-protected AuNCs, they have been employed extensively for diverse applications. The biological applications, particularly in bioimaging, biosensing, disease therapy and biocatalysis have been described in detail herein. Finally, current challenges and future potential prospects of bio-templated AuNCs in biological research are briefly discussed. [ABSTRACT FROM AUTHOR]

Modulating the assembly pathway is an indispensable strategy for optimizing the performance of optical materials. However, implementing this strategy is nontrivial for metal nanocluster building blocks, due to the limited functional modification of nanoclusters and complexity of their emission mechanism. In this report, we demonstrate that a gold nanocluster modified by 4,6‐diamino‐2‐pyrimidinethiol (DPT‐AuNCs) self‐assembles into two distinct aggregation structures in methanol (MeOH)/water mixed solvent, thus exhibiting pathway complexity. Kinetic studies show that DPT‐AuNCs firstly assembles into non‐luminescent nanofibers (kinetically controlled), which further transforms into strongly luminescent microflowers (thermodynamically controlled). In‐depth analysis of the assembly mechanism reveals that the transformation of aggregation structures involves the disassembly of nanofibers and a subsequent nucleation‐growth process. Temperature‐dependent photoluminescence (PL) spectroscopy and infrared (IR) measurements reveal that inter‐cluster hydrogen bonding bridged by solvent molecules and C−H⋅⋅⋅π interaction are the key factors for emission enhancement. The photoluminescent property of DPT‐AuNCs can be controlled by varying the cosolvent in water, enabling DPT‐AuNCs to distinguish different kind of alcohols, particularly the isomerism n‐propanol (NPA) and isopropanol (IPA). Additionally, the addition of seeds effectively regulate the assembly kinetics of DPT‐AuNCs. This study advances our understanding of assembly pathways and improves the luminescent performance of nanoclusters (NCs). [ABSTRACT FROM AUTHOR]

The identification and detection of various types of explosives are essential for human health and environmental monitoring. Array-based sensing approach offers significant advantages in detecting multi-analytes simultaneously, thereby holding great potential in identifying multiple explosives. Here, we report a tri-channel fluorescence array composed of three distinct fluorescence probes based on gold nanoclusters and nicotinamide adenine dinucleotide with well-separated emission colors. Through the specific interactions of explosives with different fluorescent probes and the yielded response patterns, seven explosives can be successfully distinguished with 100% accuracy. In particular, the sensor array exhibits excellent performance in the quantitative analysis of individual explosive and the differentiation of multiple explosive mixtures. To facilitate the field detection towards practical application, the tri-channel fluorescence array was further integrated with polymer hydrogels. The fabricated portable hydrogel-based array sensors can not only visually identify seven different explosives by their distinct fluorescence color change, but also enable quantitative detection based on linear discriminant analysis (LDA) together with a smartphone. This study illustrates the great potential of hydrogel-based fluorescence sensor array as robust sensors for explosives, which also holds significant promise for the development of portable explosive devices towards practical application. [ABSTRACT FROM AUTHOR]

Xuefeng Hou,1– 4,* Qi Chen,1,* Ying Fang,5 Li Zhang,1 Shuoheng Huang,1 Minjie Xu,1 Yaning Ren,1 Zhansen Shi,1 Yan Wei,1 Lihua Li1– 4 1School of Pharmacy, Wannan Medical College, Wuhu, Anhui Province, People’s Republic of China; 2Anhui Provincial Engineering Laboratory for Screening and Re-Evaluation of Active Compounds of Herbal Medicines in Southern Anhui, Wannan Medical College, Wuhu, Anhui Province, People’s Republic of China; 3Anhui Provincial Engineering Research Center for Polysaccharide Drugs, Wannan Medical College, Wuhu, Anhui Province, People’s Republic of China; 4Drug Research and Development Center, Wannan Medical College, Wuhu, Anhui Province, People’s Republic of China; 5School of Pharmacy, Shanghai University of Traditional Chinese Medicine, Shanghai, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yan Wei; Lihua Li, School of Pharmacy, Wannan Medical College, No. 22, West Wenchang Road, Wuhu, 241002, People’s Republic of China, Email yanwei@wnmc.edu.cn; llh05530226@126.comBackground: Breast cancer presents significant challenges due to the limited effectiveness of available treatments and the high likelihood of recurrence. iRGD possesses both RGD sequence and C-terminal sequence and has dual functions of targeting and membrane penetration. iRGD-modified nanocarriers can enhance drug targeting of tumor vascular endothelial cells and penetration of new microvessels, increasing drug concentration in tumor tissues.Methods: The amidation reaction was carried out between SiO2/AuNCs and iRGD/PTX, yielding a conjugated drug delivery system (SiO2/AuNCs-iRGD/PTX, SAIP@NPs). The assessment encompassed the characterization of the morphology, particle size distribution, physicochemical properties, in vitro release profile, cytotoxicity, and cellular uptake of SAIP@NPs. The tumor targeting and anti-tumor efficacy of SAIP@NPs were assessed using a small animal in vivo imaging system and a tumor-bearing nude mice model, respectively. The tumor targeting and anti-tumor efficacy of SAIP@NPs were assessed utilizing a small animal in vivo imaging system and an in situ nude mice breast cancer xenograft model, respectively.Results: The prepared SAIP@NPs exhibited decent stability and a certain slow-release effect in phosphate buffer (PBS, pH 7.4). In vitro studies had shown that, due to the dual functions of transmembrane and targeting of iRGD peptide, SAIP@NPs exhibited strong binding to integrin αvβ 3, which was highly expressed on the membrane of MDA-MB-231 cells, improving the uptake capacity of tumor cells, inhibiting the rapid growth of tumor cells, and promoting tumor cell apoptosis. The results of animal experiments further proved that SAIP@NPs had longer residence time in tumor sites, stronger anti-tumor effect, and no obvious toxicity to major organs of experimental animals.Conclusion: The engineered SAIP@NPs exhibited superior functionalities including efficient membrane permeability, precise tumor targeting, and imaging, thereby significantly augmenting the therapeutic efficacy against breast cancer with a favorable safety profile. Keywords: silicon dioxide nanoparticles, gold nanoclusters, iRGD penetrating peptide, integrin αvβ 3, tumor targeting, breast cancer

We present (3-amino-1,2,4-triazole-5-thiol, ATT)-modified gold nanoclusters (AGNCs) enabling biofilm-targeting and NIR-II light-responsive antibiofilm therapy even at a low laser power density (0.5 W/cm2) for a short-time irradiation (5 min), which can interact with the extracellular DNA to achieve precise treatment and is highly effective in eradicating biofilms in infected catheter implantation model with minimal side effects. [Display omitted] • The AGNCs can target the biofilm by interacting with the extracellular DNA through the formation of hydrogen bonds between the amine groups on the ATT and the hydroxyl groups of the extracellular DNA. • By employing near-infrared (NIR)-II light-responsive therapy, the AGNCs effectively eradicated biofilms with a dispersion rate up to 90 % even at a low power density (0.5 W/cm2) for short-time irradiation (5 min). • Our study suggests the great potential of the AGNCs for long-term prevention and elimination of the biofilm-mediated infections with minimal side effects. The biofilm-mediated implant infections pose a huge threat to human health. It is urgent to explore strategies to reverse this situation. Herein, we design 3-amino-1,2,4-triazole-5-thiol (ATT)-modified gold nanoclusters (AGNCs) to realize biofilm-targeting and near-infrared (NIR)-II light-responsive antibiofilm therapy. The AGNCs can interact with the bacterial extracellular DNA through the formation of hydrogen bonds between the amine groups on the ATT and the hydroxyl groups on the DNA. The AGNCs show photothermal properties even at a low power density (0.5 W/cm2) for a short-time (5 min) irradiation, making them highly effective in eradicating the biofilm with a dispersion rate up to 90 %. In vivo infected catheter implantation model demonstrates an exceptional high ability of the AGNCs to eradicate approximately 90 % of the bacteria encased within the biofilms. Moreover, the AGNCs show no detectable toxicity or systemic effects in mice. Our study suggests the great potential of the AGNCs for long-term prevention and elimination of the biofilm-mediated infections. [ABSTRACT FROM AUTHOR]

[Display omitted] • A portable assay kit for plant volatile (E) -2-hexenal, based on luminescent gold nanoclusters hydrogel, is proposed for the first time. • Michael addition reaction and etching ability of cysteine ensure anti-interference capacity. • The portable hydrogel kit demonstrates the potential for early identification of late blight in potato plants. Plants exhibit rapid responses to biotic and abiotic stresses by releasing a range of volatile organic compounds (VOCs). Monitoring changes in these VOCs holds the potential for the early detection of plant diseases. This study proposes a method for identifying late blight in potatoes based on the detection of (E) -2-hexenal, one of the major VOC markers released during plant infection by Phytophthora infestans. By combining the Michael addition reaction with cysteine-mediated etching of aggregation-induced emission gold nanoclusters (Au NCs), we have developed a portable hydrogel kit for on-site detection of (E) -2-hexenal. The Michael addition reaction between (E) -2-hexenal and cysteine effectively alleviates the etching of cysteine-mediated Au NCs, leading to a distinct fluorescence color change in the Au NCs, enabling a detection limit of 0.61 ppm. Utilizing the superior loading and diffusion characteristics of the three-dimensional structure of agarose hydrogel, our sensor demonstrated exceptional performance in terms of sensitivity, selectivity, reaction time, and ease of use. Moreover, quantitative measurement of (E) -2-hexenal was made easier by using ImageJ software to transform fluorescent images from the hydrogel kit into digital data. Such method was effectively used for the early detection of potato late blight. This study presents a low-cost, portable fluorescent analytical tool, offering a new avenue for on-site detection of plant diseases. [ABSTRACT FROM AUTHOR]

Chemiluminescence (CL) imaging, characterized by its high signal-to-noise ratio, has emerged as a highly promising approach for noninvasive and efficient tumor detection. Nevertheless, the development of efficient near-infrared (NIR) emission CL probes with good biocompatibility for precise tumor diagnosis remains a challenge. In the present study, we designed and synthesized a biocompatible NIR CL nanoparticle with aggregation-induced emission characteristics, named CPPO/BSA@AuNCs. Specifically, bis-(2,4,5-trichloro-6-carbopentoxyphenyl) oxalate (CPPO) was encapsulated by bovine serum albumin-capped gold nanoclusters (BSA@AuNCs) with aggregation-induced NIR emission properties. The nanoprobe demonstrated high CL signals with an extremely long lifetime and could be employed for quantitative analysis of reactive oxygen species, such as H2O2. Importantly, the NIR CL signal could effectively penetrate tissues with a penetration depth exceeding 27 mm, exhibiting significantly superior performance compared to the NIR fluorescence signal and blue CL signal. In vivo studies using mice bearing the 4T1 primary breast tumor and intraperitoneal metastases demonstrated that nanoprobe-based NIR CL imaging could effectively distinguish tumors from normal tissues, paving the way for CL-guided deep tumor diagnosis and surgery. [ABSTRACT FROM AUTHOR]

A dual-emission ratio-fluorescent sensing nanohybrid based on Radix Hedysari green-synthesized carbon quantum dots (CDs) and glutathione-functionalized gold nanoclusters (GSH-AuNCs) had been developed for the determination of cefodizime sodium (CDZM). The designed fluorescence nanohybrid had two significant fluorescence emission peaks at 458 nm and 569 nm when excited at 360 nm, which was attributed to the CDs and GSH-AuNCs. With the addition of CDZM, the fluorescence at 458 nm was slightly weakened while the fluorescence at 569 nm was enhanced obviously. Based on the relationship between the I569/I458 fluorescence intensity ratio and the concentration of CDZM, the designed nanohybrid exhibited a good linearity range of 1.0–1000.0 μM and the limit of detection (LOD) was 0.19 μM. The method was finally applied in the detection of CDZM in urine, showing the potential applications in complicated biological samples. [ABSTRACT FROM AUTHOR]

Gold nanoclusters are a smart platform for sensing potassium ions (K+). They have been synthesized using bovine serum albumin (BSA) and valinomycin (Val) to protect and cap the nanoclusters. The nanoclusters (Val-AuNCs) produced have a red emission at 616 nm under excitation with 470 nm. In the presence of K+, the valinomycin polar groups switch to the molecule's interior by complexing with K+, forming a bracelet structure, and being surrounded by the hydrophobic exterior conformation. This structure allows a proposed fluorometric method for detecting K+ by switching between the Val-AuNCs' hydrophilicity and hydrophobicity, which induces the aggregation of gold nanoclusters. As a result, significant quenching is seen in fluorescence after adding K+. The quenching in fluorescence in the presence of K+ is attributed to the aggregation mechanism. This sensing technique provides a highly precise and selective sensing method for K+ in the range 0.78 to 8 µM with LOD equal to 233 nM. The selectivity of Val-AuNCs toward K+ ions was investigated compared to other ions. Furthermore, the Val-AuNCs have novel possibilities as favorable sensor candidates for various imaging applications. Our detection technique was validated by determining K+ ions in postmortem vitreous humor samples, which yielded promising results. [ABSTRACT FROM AUTHOR]

The fluorescent emission and the photocatalytic activity of gold nanoclusters (AuNCs) are important properties of AuNCs. Here, we synthesized water-soluble, captopril (Capt) and glutathione (GSH) covered Au25(Capt)18 and Au15(GSH)13 nanoclusters and investigated their fluorescence stabilities which are correlated with the photo-redox of their surface. It was observed that Au25(Capt)18 exhibited a decay in its two-photon fluorescence emission induced by surface oxidation upon irradiation of femtosecond near-infrared laser (810 nm, 300 mW) in the presence of oxygen (O2). On the other hand, the two-photon fluorescence from Au15(GSH)13 was stable upon the same excitation. The different stabilities of the fluorescence of the two AuNCs were attributed to their different band gaps. This interpretation was confirmed by one-photon excitation with photon energy beyond the band gaps of the two AuNCs. Using experiments with the addition of several agents, the photocat alytic redox activities of gold atoms on the surface of Au25(Capt)18 were understood and tuned. [ABSTRACT FROM AUTHOR]

Among various hybrid nanomaterials, the combination of plasmonic nanoparticles and fluorophores in a single multifunctional nanoplatform, so‐called plasmophores, has attracted significant attention in different fields such as dark field, fluorescence, and photoacoustic imaging, biosensing, photothermal, and photodynamic therapy. Herein, author report a facile and controlled synthesis route of hybrid nanoplatforms composed of fluorescent gold nanoclusters (GNCs) coupled to plasmonic gold nanorods (GNRs) using controlled silica (SiO2) dielectric spacers of different thicknesses from now on referred to as GNR@SiO2@GNC plasmophores. The results show different degrees of plasmon‐enhanced fluorescence of the GNCs in their plasmophore hybrid system when placed at different distances from the plasmonic cores of the GNRs. On the other hand, these plasmophores show enhanced thermal stability compared to GNRs@CTAB (CTAB, cetyl trimethyl ammonium bromide). This results also demonstrated that upon annealing at elevated temperatures (800–1000 °C), the GNRs in the plasmophores are more thermally stable and robust than the GNRs@CTAB. More surprisingly, despite the commonly reported very low melting temperature of smaller‐size nanocrystals, the GNCs in the plasmophores showed high thermal stability and do not exhibit significant structural changes at elevated temperatures (800–1000 °C). [ABSTRACT FROM AUTHOR]

An enzymatic fluorescent probe is developed for the selective detection of glucose. In this work, a Bovine Serum Albumin stabilized gold nanocluster (BSA‐AuNCs) was synthesized by microwave assisted method, and it is modified with glucose oxidase, thereby a fluorescent enzymatic sensor (BSA‐AuNCs@GoX) was designed for the sensitive detection of glucose with a limit of detection of 0.03 mM. The red fluorescence exhibited by the probe is quenched by the production of H2O2 on addition of glucose via. a static quenching mechanism from UV visible absorption and Fluorescence lifetime results. The developed probe exhibits good selectivity and sensitivity with other coexisting molecular species such as glycine, creatinine, methionine, histidine, uric acid, albumin, and ions such as sodium, potassium, calcium, magnesium, zinc etc. that appear in the body fluid. The practical applicability was studied in paper strip and extended its reproducibility in biological matrixes such as human serum and urine and found a good recovery percentage of 94–101 %. By this way, we have fabricated an effective fluorescent enzymatic "turn‐off" sensing probe for the detection of glucose. [ABSTRACT FROM AUTHOR]

The surfactant cetyltrimethylammonium bromide (CTAB) induces the aggregation of gold nanoclusters (GNCs), leading to the development of a proposed fluorometric technique for detecting thiocyanate (SCN−) ions based on an anti-aggregation mechanism. This approach is straightforward to execute, highly sensitive, and selective. A significant quenching effect occurs in fluorescence upon using the aggregation agent CTAB in GNCs synthesis, resulting in a transition from intense red fluorescence to dim red. The decrease in fluorescence intensity of GNCs in the presence of CTAB is caused by the mechanism of fluorescence quenching mediated by aggregation. As the levels of SCN− rise, the fluorescence of CTAB-GNCs increases; this may be detected using spectrofluorometry or by visually inspecting under UV irradiation. The recovery of red fluorescence of CTAB-GNCs in the presence of SCN− enables the precise and discerning identification of SCN− within the concentration range of 2.86–140 nM. The minimum detectable concentration of the SCN− ions was 1 nM. The selectivity of CTAB-GNCs towards SCN− ions was investigated compared to other ions, and it was demonstrated that CTAB-GNCs exhibit exceptional selectivity. Furthermore, we believe that CTAB-GNCs have novel possibilities as favorable sensor candidates for various industrial applications. Our detection technique was validated by analyzing SCN− ions in milk samples, which yielded promising results. [ABSTRACT FROM AUTHOR]

Gold nanoclusters (Au NCs) with bright emission and unique chemical reactivity characters have been widely applied for optical sensing and imaging. With a combination of surface modifications, effective therapeutic treatments of tumors are realized. In this review, we summarize the recently adopted biosensing and therapy events based on Au NCs. Homogeneous and fluorometric biosensing systems toward various targets, including ions, small molecules, reactive oxygen species, biomacromolecules, cancer cells, and bacteria, in vitro and in vivo, are presented by turn-off, turn-on, and ratiometric tactics. The therapy applications are concluded in three aspects: photodynamic therapy, photothermal therapy, and as a drug carrier. The basic mechanisms and performances of these systems are introduced. Finally, this review highlights the challenges and future trend of Au NC-based biosensing and therapy systems. [ABSTRACT FROM AUTHOR]

[Display omitted] Due to lack of effective, early and non-invasive diagnostic as well as treatment tools, the surgical treatment opportunities for lung squamous cell carcinoma (SCC) are limited, resulting in high mortality rates. Therefore, the combination of targeted recognition and precise treatment of lung SCC is of great significance. In this study, a multifunctional nanoparticle is designed and synthesized, which specifically identifies lung SCC cells for target imaging and therapy. Desmoglein-3 (Dsg-3), a transmembrane glycoprotein found in desmosomes, is highly expressed in lung SCC cells. Gold nanoclusters (AuNCs) conjugated with Dsg-3 antibodies to form Au-Dsg-3 through coupling reaction. The results showed that the fluorescence imaging (FI) intensity and computed tomography (CT) signal of Au-Dsg-3 significantly increased within 6 h in vitro and in vivo , achieving dual-modal imaging to detect lung SCC effectively. Besides, Au-Dsg-3 even integrates targeted photothermal therapy (PTT) characteristics in a single nanoparticle. When exposed to near-infrared radiation (NIR), the temperature of the tumor site increased rapidly and reached a high temperature of 53.3 °C after 600 s, causing tumor ablation and growth inhibition. In summary, Au-Dsg-3 provides a key platform for targeted biological imaging and collaborative PTT, which demonstrates good performance on lung SCC. [ABSTRACT FROM AUTHOR]

To develop nontoxic and stable fluorescent emission B-Cu nanoclusters (NCs) for the specific detection of dopamine at low concentrations in cerebrospinal fluid (CSF). Fluorescent gold and copper NCs conjugated with proteins, such as bovine serum albumin (BSA), offer photostability and healthcare potential. This study focused on fabricating B-Cu NCs that exhibited superior characteristics for sensitive dopamine detection. The study employed various instrumental techniques including attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), spectrofluorometry, and transmission electron microscopy (TEM) to characterize the formulated B-Cu NCs. The NCs were synthesized, resulting in particle size ∼300 nm. The highest observed fluorescence was recorded at 24542.81 relative fluorescence units (RFU). The introduction of dopamine at concentrations of 0.1, 0.2, 0.3, and 0.4 ng/mL led to decreased fluorescence in both B-Au and B-Cu NCs due to an electron transport system. This reduction in fluorescence allowed dopamine concentration analysis in phosphate buffer and biological fluids such as blood plasma and CSF. B-Cu NCs showed potential as a biosensing system for point-of-care (POC) applications, specifically for diagnosing schizophrenia. The study successfully synthesized stable and nontoxic B-Cu NCs with enhanced fluorescent emission properties. These NCs exhibited the capacity to detect dopamine at low concentrations in CSF. The study's findings hold promise for future applications, particularly in the development of a B-Cu NCs-based biosensing system for convenient POC detection of schizophrenia by both patients and clinicians. The potential impact of this technology on healthcare and biomedical fields is substantial. [ABSTRACT FROM AUTHOR]

Delayed wound healing in skin burn injuries is common owing to inhibition of proliferation caused by excessive inflammation, necrosis, autophagy, and oxidative stress. Gold nanoclusters modified with lipoic acid (AuNCs) exhibited antioxidant and anti-inflammatory effects in a murine burn healing model. However, the impact of the AuNCs on dermal cell proliferation and granulation tissue formation remains unclear. We therefore examined their effects on dermal cell proliferation, the cell cycle, and the signaling pathways involved. AuNCs were combined with a silk fibroin scaffold and tested in a mouse burn model and human dermal fibroblasts in vitro. Combined with the silk fibroin scaffold, 50 nmol/L of AuNCs activated fibroblast differentiation, collagen deposition, and angiogenesis, increasing granulation-tissue formation, reducing tissue necrosis and systemic inflammatory response, and improving wound healing in the model. The AuNCs increased PI3K/Akt signaling pathway phosphorylation in human dermal fibroblasts, upregulating protein expression of cyclin A, B, and CDK1, which participate in the G2/M cell cycle phase, ultimately promoting fibroblast proliferation. These findings support the beneficial effects of AuNCs on burn wound healing. We suggested that AuNCs on a silk fibroin scaffold or other vector is a potential clinical strategy for burn wound treatment.

Metal–organic frameworks (MOF) derived nitrogen‐doped carbon‐supported monodisperse Fe (Fe–N–C) catalysts are intensively studied, but great challenges remain in understanding the relationship between the coordination structure and the performance of Fe–N–C nanozymes. Herein, a novel nanocluster ligand‐bridging strategy is proposed for constructing Fe‐S1N4 structures with axially coordinated S and Au nanoclusters on ZIF‐8 derived Fe–N–C (labeled Aux/Fe‐S1N4‐C). The axial Au nanoclusters facilitate electron transfer to Fe active sites, utilizing the bridging ligand S as a medium, thereby enhancing the oxygen adsorption capacity of composite nanozymes. Compared to Fe‐N‐C, Aux/Fe‐S1N4‐C exhibits high oxidase‐like specificity and activity, and holds great potential for detecting acetylcholinesterase activity with a detection limit of 5.1 µU mL−1, surpassing most reported nanozymes. [ABSTRACT FROM AUTHOR]

Sub-nanometer-sized gold nanoclusters (Au NCs) were prepared via the spontaneous reduction of [AuCl4]−- ions with a hydroxamate derivative of L-tryptophan (Trp) natural amino acid (TrpHA). The prepared TrpHA-Au NCs possess intense blue emission (λem = 470 nm; λex = 380 nm) with a 2.13% absolute quantum yield and 1.47 ns average lifetime. The Trp-stabilized noble metal NCs are excellent metal ion sensors for Fe3+, but in this work, we highlighted that the incorporation of the hydroxamate functional group with an excellent metal ion binding capability can tune the selectivity and sensitivity of these NCs, which is a promising way to design novel strategies for the detection of other metal ions as well. Moreover, their simultaneous identification can also be realized. By decreasing the sensitivity of our nano-sensor for Fe3+ (limit of detection (LOD) ~11 µM), it was clearly demonstrated that the selectivity for Cu2+-ions can be significantly increased (LOD = 3.16 µM) in an acidic (pH = 3–4) condition. The surface-bounded TrpHA molecules can coordinate the Cu2+ confirmed by thermodynamic data, which strongly generates the linking of the NCs via the Cu2+ ions in acidic pH, and a parallel fluorescence quenching occurs. In the case of Fe3+, the degree of quenching strongly depends on the metal ion concentration, and it only occurs when the NCs are not able to bind more Fe3+ (~10 µM) on the surface, causing the NCs' aggregation. [ABSTRACT FROM AUTHOR]

Metalloenzymes are able to catalyze complex biochemical reactions in cellular (aqueous) media with high efficiency. In recent years, a variety of metal-containing single-chain nanoparticles (SCNPs) have been synthesized as simplified metalloenzyme-mimetic nano-objects. However, most of the metal-containing SCNPs reported so far contained complexed metal ions but not metal nanoclusters (NCs) with diameter <5 nm, which could be used as powerful, emerging catalysts. Herein, we report the synthesis of gold nanoclusters (Au-NCs) within SCNPs and the further use of Au-NCs/SCNPs as catalytic nanoreactors in water. We demonstrate that a common motif contained in several drugs (i.e., the aminophenyl–oxazolidinone fragment present in Rivaroxaban, Sutezolid, and Linezolid) can be efficiently prepared in water from a hydrophobic precursor compound by using the Au-NCs/SCNPs as efficient catalytic nanoreactors. In summary, this work paves the way forthe synthesis of metal–NCs/SCNPs for advanced catalysis in aqueous media. [ABSTRACT FROM AUTHOR]

Sensors for which the output signal is an intensity change for a single-emission peak are easily disturbed by many factors, such as the stability of the instrument, intensity of the excitation light, and biological background. However, for ratiometric fluorescence sensors, the output signal is a change in the intensity ratio of two or more emission peaks. The fluorescence intensity of these emission peaks is similarly affected by external factors; thus, these sensors have the ability to self-correct, which can greatly improve the accuracy and reliability of the detection results. To accurately image glutathione (GSH) in cells, gold nanoclusters (AuNCs) with intrinsic double emission at wavelengths of 606 nm and 794 nm were synthesized from chloroauric acid. With the emission peak at 606 nm as the recognition signal and the emission peak at 794 nm as the reference signal, a near-infrared dual-emission ratio fluorescence sensing platform was constructed to accurately detect changes in the GSH concentration in cells. In vitro and in vivo analyses showed that the ratiometric fluorescent probe specifically detects GSH and enables ultrasensitive imaging, providing a new platform for the accurate detection of active small molecules. [ABSTRACT FROM AUTHOR]

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Surgical resections of solid tumors guided by visual inspection of tumor margins have been performed for over a century to treat cancer. Near-infrared (NIR) fluorescence labeling/imaging of tumor in the NIR-I (800 to 900 nm) range with systemically administrated fluorophore/tumor-targeting antibody conjugates have been introduced to improve tumor margin delineation, tumor removal accuracy, and patient survival. Here, we show Au25 molecular clusters functionalized with phosphorylcholine ligands (AuPC, ~2 nm in size) as a preclinical intratumorally injectable agent for NIR-II/SWIR (1,000 to 3,000 nm) fluorescence imaging-guided tumor resection. The AuPC clusters were found to be uniformly distributed in the 4T1 murine breast cancer tumor upon intratumor (i.t.) injection. The phosphocholine coating afforded highly stealth clusters, allowing a high percentage of AuPC to fill the tumor interstitial fluid space homogeneously. Intra-operative surgical navigation guided by imaging of the NIR-II fluorescence of AuPC allowed for complete and non-excessive tumor resection. The AuPC in tumors were also employed as a photothermal therapy (PTT) agent to uniformly heat up and eradicate tumors. Further, we performed in vivo NIR-IIb (1,500 to 1,700 nm) molecular imaging of the treated tumor using a quantum dot-Annexin V (QD-P3 -Anx V) conjugate, revealing cancer cell apoptosis following PTT. The therapeutic functionalities of AuPC clusters combined with rapid renal excretion, high biocompatibility, and safety make them promising for clinical translation. [ABSTRACT FROM AUTHOR]

The crystal structures of 4 ligand‐rotational isomers of Au25(PET)18 are presented. Two new ligand‐rotational isomers are revealed, and two higher‐quality structures (allowing complete solution of the ligand shell) of previously solved Au25(PET)18 clusters are also presented. One of the structures lacks an inversion center, making it the first chiral Au25(SR)18 structure solved. These structures combined with previously published Au25(SR)18 structures enable an analysis of the empirical ligand conformation landscape for Au25(SR)18 clusters. This analysis shows that the dihedral angles within the PET ligand are restricted to certain observable values, and also that the dihedral angle values are interdependent, in a manner reminiscent of biomolecule dihedral angles such as those in proteins and DNA. The influence of ligand conformational isomerism on optical and electronic properties was calculated, revealing that the ligand conformations affect the nanocluster absorption spectrum, which potentially provides a way to distinguish between isomers at low temperature. [ABSTRACT FROM AUTHOR]

Nitrite ( NO 2 - ) is often added to food as a food additive, but the overuse of nitrite will pose a threat to human health, so it is important to establish a rapid detection method for nitrite in related food. In this work, gold nanoparticles (AuNPs) were synthesized by in situ reduction of methanobactin (Mb); it is a small bioactive peptide. HS-β-cyclodextrin (HS-β-CD) with supramolecular recognition function was coordinated with Mb/AuNPs by Au-S bond to form HS-β-CD@Mb/AuNPs. HS-β-CD@Mb/AuNPs were modified onto the surface of gold electrode by electrodeposition to successfully prepare the biosensor (HS-β-CD@Mb/AuNPs/Au). The HS-β-CD@Mb/AuNPs/Au was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), ultraviolet spectroscopy (UV), Fourier infrared spectroscopy (FTIR), fluorescence spectrometer (FL), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The established biosensor was successfully applied to the detection of nitrite in real samples, and the mechanism of NO2− oxidation was analyzed. The detection limit of the established detection system was as low as 0.013 μM in the linear range of 0.1–10,000 μM, the recoveries were 96.53–102.54%, and the selectivity of the sensor is demonstrated by anti-interference experiment. Also compared to the previously described electrochemical sensors, the newly developed ones have better sensitivity (50.7137 μA μM−1 cm−2) and selectivity. These results suggest that the work provides a new way for the accurate monitoring of nitrite in environmental and food safety. [ABSTRACT FROM AUTHOR]

CO oxidation is an important reaction from the perspective of environment remediation techniques. The improvised, better end-of-pipe solution are desired to reduce the impact of anthropogenic activities on the environment. CO oxidation can take place at the surface of gold nanoparticles even at low temperatures, thereby providing solution to cold-emission problem. In this study, we explore the effect of water in adsorbed state on the reaction profile of CO oxidation catalysed by gold nanoclusters. It has been found that the main effect of water adsorbed onto gold nanoclusters is to reduce the barrier for carbonate formation. The carbonate formation is reported to negatively impact the catalytic properties of gold nanocluster. Here, we also report an alternative pathway through which the carbonate decomposition can be accomplished leading to the regeneration of the catalyst surface. This Eley - Rideal pathway involves reaction between CO and nanocluster-carbonate adduct. No effect of adsorbed water on energetics of carbonate decomposition at the surface of gold nanocluster has been observed. [ABSTRACT FROM AUTHOR]

Simple and sensitive detection of cardiac biomarkers is of great significance for early diagnosis and prevention of acute myocardial infarction (AMI). Here, a ratiometric fluorescent nanohybrids probe (AuNCs-QDs) was synthesized through the coupling of bovine serum albumin-functionalized gold nanoclusters (AuNCs) with CdSe/ZnS quantum dots (QDs) to realize simple and sensitive detection of cardiac biomarker myoglobin (Mb). The AuNCs-QDs probe shows pink fluorescence under UV light, with two emission peaks at 468 nm and 630 nm belonging to QDs and AuNCs, respectively. Importantly, the presence of Mb caused fluorescence quenching of the blue-emitting QDs, thereby inhibiting the fluorescence resonance energy transfer (FRET) process between QDs and AuNCs, and reducing the fluorescence intensity ratio (F468/F630) of AuNCs-QDs probe effectively. As the concentration of Mb increases, the ratiometric fluorescent probe also exhibits a visible fluorescence color change. The detection limit was as low as 4.99 μg/mL, and the response of the probe to Mb showed a good linear relationship up to 0.52 mg/mL. Moreover, the probe has excellent specificity for Mb. Besides, the AuNCs-QDs has been applied to detect Mb of urine samples. More importantly, we also developed an AuNCs-QDs probe modified smartphone-aided paper-based strip for on-site monitoring of Mb. As far as we know, this is the first report of a smartphone-aided paper-based strip for on-site quick monitoring of Mb, which provides a useful approach for AMI biomarker monitoring and may can be extended to other medical diagnostics. [ABSTRACT FROM AUTHOR]

Chronic inflammation can delay wound healing, eventually leading to tissue necrosis and even cancer. Developing real-time intelligent inflammation monitoring and treatment to achieve effective wound management is important to promote wound healing. In this study, a smart multifunctional hydrogel (Hydrogel@Au NCs&DG) was proposed to monitor and treat the wound inflammation. It was prepared by mixing 3-carboxy-phenylboronic acid modified chitosan (CS-cPBA), β-glycerophosphate (β-GP), albumin-protected gold nanoclusters (BSA-Au NCs), and dipotassium glycyrrhizinate (DG) about 10 s. In this hydrogel, CS-cPBA and β-GP are crosslinked together by boric acid ester bond and hydrogen bond to form the main hydrogel network, endowing the hydrogel with self-healing and injectable properties to adapt irregular wounds. Importantly, the as-prepared hydrogel with good biocompatibility and excellent adhesion property could directly determine the H2O2 to monitor the wound microenvironment by visible fluorescence change of BSA-Au NCs and then guide the frequency of dressing change to eliminate inflammation. The results demonstrated that the as-prepared smart hydrogel could be expected to serve as an intelligent wound dressing to promote inflammation-infected wound healing.

Gold nanoclusters are peculiar objects promising in view of qualitative and quantitative determination of various species, including heavy metal ions and biological molecules. We have recently discovered that introducing sodium azide in the reaction mixture during gold nanocluster synthesis in the presence of citrate and adenosine monophosphate can tune the product emission from blue to yellow. Taking advantage of the factorial design of the experiment, we have optimized the synthesis conditions to obtain pure blue and yellow emitters and investigate their sensitivity to a series of inorganic salts. The experiments have revealed selective quenching of the nanocluster’s fluorescence in the presence of mercury(II) ions.

Multifunctional targeted drug delivery systems have been explored as a novel cancer treatment strategy to overcome limitations of traditional chemotherapy. The combination of photodynamic therapy and chemotherapy has been shown to enhance efficacy, but the phototoxicity of traditional photosensitizers is a challenge. In this study, we prepared a multi-sensitive composite hydrogel containing gold nanoclusters (Au NCs) and the temperature-sensitive antitumor drug 5-fluorourac il (5-FU) using carboxymethyl cellulose (Carr) as a dual-functional template. Au NCs were synthesized using sodium borohydride as a reducing agent and potassium as a promoter. The resulting Au NCs were embedded in the Carr hydrogel, which was then conjugated with lactobionic acid (LA) as a targeting ligand. The resulting Au NCs/5-FU@Carr-LA composite hydrogel was used for synergistic photodynamic therapy (PDT), photothermal therapy (PTT), and chemotherapy. Au NCs/5-FU@Carr-LA releases the drug faster at pH 5.0 due to the acid sensitivity of the Carr polymer chain. In addition, at 50 °C, the release rate of Au NCs/5-FU@Carr-LA is 78.2%, indicating that the higher temperature generated by the photothermal effect is conducive to the degradation of Carr polymer chains. The Carr hydrogel stabilized the Au NCs and acted as a matrix for drug loading, and the LA ligand facilitated targeted delivery to tumor cells. The composite hydrogel exhibited excellent biocompatibility and synergistic antitumor efficacy, as demonstrated by in vitro and in vivo experiments. In addition, the hydrogel had thermal imaging capabilities, making it a promising multifunctional platform for targeted cancer therapy.

Preserving ultrasmall sizes of metal particles is a key challenge in the study of heterogeneous metal-based catalysis. Confining the ultrasmall metal clusters in a well-defined crystalline porous zeolite has emerged as a promising approach to stabilize these metal species. Successful encapsulation can be achieved by the addition of ligated metal complexes to zeolite synthesis gel before hydrothermal synthesis. However, controlling the metal particle size during post-reduction treatment remains a major challenge in this approach. Herein, an in situ incorporation strategy of pre-made atomically precise gold clusters within Na-LTA zeolite was established for the first time. With the assistance of mercaptosilane ligands, the gold clusters were successfully incorporated within the Na-LTA without premature precipitation and metal aggregation during the synthesis. We have demonstrated that the confinement of gold clusters within the zeolite framework offers high stability against sintering, leading to superior CO oxidation catalytic performance (up to 12 h at 30 °C, with a space velocity of 3000 mL g−1 h−1). [ABSTRACT FROM AUTHOR]

Nanomedicine presents exciting new opportunities for the detection and treatment of cancer. Current cancer imaging methods and treatment approaches in clinics frequently fall short of entirely curing cancer and can have severe side effects. Theranostic nanoparticles, however, have the potential to revolutionize effective cancer treatment and early cancer detection. The objective of this study is to show how magnetic iron oxide nanoparticles and photoluminescent gold nanoclusters (MN‐AuNCs) may be combined effectively to produce bimodal imaging nanoparticles that possess magnetic and optical properties and can be used for both magnetic resonance imaging and optical biopsy. These findings demonstrate that MN‐AuNCs, when exposed to visible light, also have the capability to produce singlet oxygen, which is necessary for photodynamic therapy of cancer. In addition, it shows that they are non‐toxic, accumulate inside the cells, and cause cell death during exposure to visible light. The creation of these MN‐AuNCs offers a novel remedy for the current shortcomings in cancer diagnosis and treatment. Since they have both therapeutic and imaging capabilities, MN‐AuNCs have the potential to improve patient outcomes while lowering the risk of negative side effects. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) fluorophores with pH‐responsive properties suggest merits in biological analyses. This work establishes a general and effective method to obtain pH‐responsive NIR emissive gold nanoclusters by introducing aliphatic tertiary amine (TA) groups into the ligands. Computational study suggests that the pH‐responsive NIR emission is associated with electronic structure change upon protonation and deprotonation of TA groups. Photo‐induced electron transfer between deprotonated TA groups and the surface Au‐S motifs of gold nanoclusters can disrupt the radiative transitions and thereby decrease the photoluminescence intensity in basic environments (pH=7–11). By contrast, protonated TA groups curb the electron transfer and restore the photoluminescence intensity in acidic environments (pH=4–7). The pH‐responsive NIR‐emitting gold nanoclusters serve as a specific and sensitive probe for the lysosomes in the cells, offering non‐invasive emissions without interferences from intracellular autofluorescence. [ABSTRACT FROM AUTHOR]

Fluorescent gold nanoclusters have been successfully used as fluorescent markers for imaging of cells and tissues, and their potential role in drug delivery monitoring is coming to the fore. In addition, the development of biosensors using structure-tunable fluorescent nanoclusters is also a prominent research field. In the case of these sensor applications, the typical goal is the selective identification of, e.g., metal ions, small molecules having neuroactive or antioxidant effects, or proteins. During these application-oriented developments, in general, there is not enough time to systematically examine the interaction between nanoclusters and relevant biomolecules/proteins from a thermodynamic viewpoint. In this way, the primary motivation of this article is to carry out a series of tests to partially fill this scientific gap. Besides the well-known fluorescent probes, the mentioned interactions were investigated using such unique measurement methods as surface plasmon resonance (SPR) and isothermal titration calorimetry (ITC). These two-dimensional (at the solid/liquid interface) and three-dimensional (in the bulk phase) measuring techniques provide a unique opportunity for the thermodynamic characterization of the interaction between different gold nanoclusters containing various surface functionalizing ligands and bovine serum albumin (BSA). [ABSTRACT FROM AUTHOR]

Gold nanoclusters are peculiar objects promising in view of qualitative and quantitative determination of various species, including heavy metal ions and biological molecules. We have recently discovered that introducing sodium azide in the reaction mixture during gold nanocluster synthesis in the presence of citrate and adenosine monophosphate can tune the product emission from blue to yellow. Taking advantage of the factorial design of the experiment, we have optimized the synthesis conditions to obtain pure blue and yellow emitters and investigate their sensitivity to a series of inorganic salts. The experiments have revealed selective quenching of the nanocluster's fluorescence in the presence of mercury(II) ions. [ABSTRACT FROM AUTHOR]

Nanomedicine shows remarkable potential to improve the efficacy of diagnosis and treatment of tumors, utilizing nanotechnologies and nanomaterials. Gold nanoclusters (AuNCs) have emerged as a highly promising option due to their exceptional optical and enzyme‐mimicking catalytic activities as well as good biocompatibility. The renal clearable clusters can enrich in the tumors upon their enhanced permeability and retention properties, which benefits the tumor‐related applications. The fluorescence of AuNCs in the second near‐infrared region possesses extraordinary penetration depth and high temporal–spatial resolution, enabling excellent in vivo imaging and real‐time monitoring of pathological process. AuNC‐based nanoplatforms represent a paradigm of integrated, efficient, intelligent, and safe treatment strategy, extending personalized tumor therapy. Meanwhile, the optical and biocatalytic properties can be modulated by adopting the atom/ligand engineering, which further enhances the efficacy of AuNCs. Herein, the advances of AuNCs in the field of diagnosis and treatment of tumors are summarized and the directions to be improved are proposed to promote the clinical translation of the AuNCs. [ABSTRACT FROM AUTHOR]

Gold nanoclusters (AuNCs) with fluorescence in the Near Infrared (NIR) by both one- and two-photon electronic excitation were incorporated in mesoporous silica nanoparticles (MSNs) using a novel one-pot synthesis procedure where the condensation polymerization of alkoxysilane monomers in the presence of the AuNCs and a surfactant produced hybrid MSNs of 49 nm diameter. This method was further developed to prepare 30 nm diameter nanocomposite particles with simultaneous NIR fluorescence and superparamagnetic properties, with a core composed of superparamagnetic manganese (II) ferrite nanoparticles (MnFe2O4) coated with a thin silica layer, and a shell of mesoporous silica decorated with AuNCs. The nanocomposite particles feature NIR-photoluminescence with 0.6% quantum yield and large Stokes shift (290 nm), and superparamagnetic response at 300 K, with a saturation magnetization of 13.4 emu g−1. The conjugation of NIR photoluminescence and superparamagnetic properties in the biocompatible nanocomposite has high potential for application in multimodal bioimaging. [ABSTRACT FROM AUTHOR]

The controversy over the emission center of metal nanoclusters (MNCs) has been going on for decades. A question important for understanding the photoluminescence mechanisms of metal clusters is whether a single cluster can contain several independent photoluminescent emitters. Herein, using the widely studied aggregation-induced emission and a ligand-exchange strategy, gold nanoclusters (Au NCs) with multiple emission peaks (∼460, ∼560, and ∼620 nm) are synthesized. The photoluminescence is excitation wavelength independent and is from supramolecular clusters formed by the assembly of functional groups on the nanoconfined surface of an individual Au NC. Water clusters confined in the hydrophobic nanocavity can also act as an emission center of Au NCs. P-band states formed by the overlapping of p-orbitals from heteroatoms (O, N, S, and P) of adjacent functional groups dominate the energy level structure of MNCs and thus the photoluminescence properties. [ABSTRACT FROM AUTHOR]

During the last decade, a great variety of ligand protected gold nanoclusters (AuNCs) have been synthesized, and their broad applications have been intensively reported. Although the spectroscopic properties of AuNCs have been comprehensively explored, the mechanism of the significant Stokes shift (> 200 nm) and the specific role played by surface ligands have not been clearly explained yet. In this study, a series of fluorescent AuNCs with huge Stokes shift (up to 530 nm) were successfully prepared by employing the rationally designed tri-peptides as the protecting ligands, and their spectroscopic properties were systematically investigated. The detailed measurements on the example product, YCY-AuNCs (Tyr-Cys-Tyr liganded AuNCs), showed that the energy absorbed by the tyrosine (~ 250 nm) can be effectively transferred through the ligand-mediated two-step Förster resonance energy transfer (FRET) process and released as fluorescence emission in the near-infrared fluorescence (NIR) range (~ 780 nm), which resulted in the significant apparent Stokes shift. The YCY ligands play a critical role by offering the tyrosine groups (donor of the first FRET pair), generating the dityrosine-like structure on the AuNCs surface (acceptor of the first FRET pair and donor of the second FRET pair), and protecting the cores (acceptor of the second acceptor). The additional ligand exchange experiments and the investigation on the other AuNCs further demonstrated that the sufficient high density of the aromatic groups is also essential to mediate the two-step FRET and achieve the remarkable Stokes shift. We believe that the aromatic ligand-mediated FRET mechanism not only offers a new theoretical explanation for the huge Stokes shift exhibited in AuNCs, but also provides a general strategy for the construction of new materials with large Stokes shift. [ABSTRACT FROM AUTHOR]

Abstract Metal–organic frameworks (MOF) derived nitrogen‐doped carbon‐supported monodisperse Fe (Fe–N–C) catalysts are intensively studied, but great challenges remain in understanding the relationship between the coordination structure and the performance of Fe–N–C nanozymes. Herein, a novel nanocluster ligand‐bridging strategy is proposed for constructing Fe‐S1N4 structures with axially coordinated S and Au nanoclusters on ZIF‐8 derived Fe–N–C (labeled Aux/Fe‐S1N4‐C). The axial Au nanoclusters facilitate electron transfer to Fe active sites, utilizing the bridging ligand S as a medium, thereby enhancing the oxygen adsorption capacity of composite nanozymes. Compared to Fe‐N‐C, Aux/Fe‐S1N4‐C exhibits high oxidase‐like specificity and activity, and holds great potential for detecting acetylcholinesterase activity with a detection limit of 5.1 µU mL−1, surpassing most reported nanozymes.

The biggest challenge of exploring the catalytic properties of under-coordinated nanoclusters is the issue of stability. We demonstrate herein that chemical dopants on sulfur-doped graphene (S-G) can be utilized to stabilize ultrafine (sub-2 nm) Au25(PET)18 clusters to enable stable nitrogen reduction reaction (NRR) without significant structural degradation. The Au25@S-G exhibits an ammonia yield rate of 27.5μgNH3⋅mgAu−1⋅h−1 at −0.5 V with faradic efficiency of 2.3%. More importantly, the anchored clusters preserve ∼ 80% NRR activity after four days of continuous operation, a significant improvement over the 15% remaining ammonia production rate for clusters loaded on undoped graphene tested under the same conditions. Isotope labeling experiments confirmed the ammonia was a direct reaction product of N2 feeding gas instead of other chemical contaminations. Ex-situ X-ray photoelectron spectroscopy and X-ray absorption near-edge spectroscopy of post-reaction catalysts reveal that the sulfur dopant plays a critical role in stabilizing the chemical state and coordination environment of Au atoms in clusters. Further ReaxFF molecular dynamics (RMD) simulation confirmed the strong interaction between Au nanoclusters (NCs) and S-G. This substrate-anchoring process could serve as an effective strategy to study ultrafine nanoclusters’ electrocatalytic behavior while minimizing the destruction of the under-coordinated surface motif under harsh electrochemical reaction conditions. [Figure not available: see fulltext.].