Interaction of amino acids and DNA nucleobases with copper: a comparative theoretical study.

Ultra-small copper nanoclusters (CuNCs) have attracted attention as efficient and sustainable catalysts due to their large surface area, quantum-size effects, readily available active sites, and cost-effective synthesis. In this work, we report the gram-scale, one-pot synthesis of orange-emitting CuNCs@2MB, stabilized by thiolate ligands, exhibiting a long fluorescence lifetime (∼3 µs). The chemical composition, surface characteristics and spectroscopic properties of the synthesized CuNCs@2MB were analyzed using MALDI-TOF MS, TEM, UV-vis, and fluorescence spectroscopy. These ultra-small CuNCs act as a robust heterogeneous catalyst for C-S cross-coupling reactions, enabling the formation of diverse thioethers. The nanoclusters demonstrated high functional group tolerance and good yields across a wide range of aryl iodides and thiols. Furthermore, a comparative study with newly synthesized nonyl chain-appended copper nanoclusters (CuNCs@2MB-NB) and other CuNCs previously reported by our group demonstrates that ligand engineering significantly influences the catalytic efficiency and product yield. Considering the significance of thioethers in the fields of pharmaceuticals, functional materials, and polymer science, this approach provides a facile and scalable method for constructing C-S bonds, offering distinct advantages over conventional copper catalysts.

We present a type of synergistic catalyst that integrates Frustrated Lewis Pair (FLP) and photocatalytic (PC) functionalities on an atomically precise copper nanocluster. By strategically functionalizing the cluster surface with 6-(dibutylamino)-1,3,5-triazine-2,4-dithiol (TRZ), we successfully synthesize a structurally well-defined nanocluster [Cu20(TRZ)9(4-F3PPh3)2H4]2-. The TRZ ligands serve a triple function: they not only stabilize the nanocluster framework but also furnish nitrogen-based Lewis basic sites. These sites, in conjunction with surface-exposed copper atoms acting as Lewis acids, form FLP-active centers capable of activating small molecules such as silanes under mild conditions. Furthermore, the TRZ ligand's triazine moiety acts as an efficient photoredox unit, driving the photocatalytic production of hydrogen peroxide through oxygen reduction. This activity, when integrated with the FLP functionality, results in an integrated system that exhibits high efficiency and selectivity in the catalytic oxidation of silanes to silanols. The catalyst demonstrates outstanding activity, selectivity, and stability under ambient conditions. This study not only presents a generalizable strategy for embedding FLP-PC bifunctionality in metal nanoclusters but also confirms the feasibility of designing high-performance cluster catalysts that operate via synergistic mechanistic pathways. The integration of FLP and PC functionalities supports efficient and selective transformations relevant to sustainable catalysis.

Understanding how structural evolution influences catalytic behavior is a central challenge in chemistry. We establish an atomically precise platform to directly probe the catalytic consequences of structural fusion in copper nanoclusters and uncover a counterintuitive anti-emergent phenomenon, wherein increased structural complexity leads to suppressed activity. By integrating thiacalix[4]arene with an ortho-hydroxyl-substituted alkynyl ligand, we enable the in situ generation and directional templating of C2 2 - dianions, achieving controlled fusion of two Cu17 units into a well-defined supercluster, {(C2)6@Na2Cu40(TC4A)6(3-HOhexC≡C)6} (Cu40). Precise regulation of the hydroxyl position allows selective isolation of the monomeric counterpart {NaCu17(TC4A)3(6-HOhexC≡C)6} (Cu17), providing a closely matched model pair to disentangle fusion effects. The generality of this C2 2 --templated fusion pathway is further supported by the isolation of Cu22 and Cu43 clusters. Comparative electrocatalytic analysis shows that, despite similar topological architectures, Cu40 exhibits markedly inferior nitrate-reduction activity relative to the Cu17 and Cu22 monomers. Notably, Cu17 delivers an optimal NH3 Faradaic efficiency of 98.45% with a production rate of 2.91 mol·h-1·g-1 at -1.0V. In situ spectroscopic experiments combined with DFT calculations reveal that fusion preserves the intrinsic nature of Cu active sites but reduces surface accessibility and perturbs local electronic environments, thereby suppressing interfacial *H formation and hindering hydrogenation of *NO intermediates.

Consuming Sunset Yellow (SY) in large quantities poses notable health hazards, creating a critical need for dependable analytical techniques to monitor its presence. In this study, we detail the preparation of highly stable copper nanoclusters capped with L-histidine (His-CuNCs), which serve as an effective fluorescent sensor for accurately measuring SY levels. These engineered nanomaterials display a vivid blue-green emission and possess outstanding resilience, especially under conditions of elevated salinity and temperature, rendering them ideal for evaluating complicated food samples. As a diagnostic tool, this sensor provided a broad linear response range from 0.3 to 90.0 µM, with a highly sensitive detection limit of 15.34 nM. Exploration of the underlying mechanisms indicated that the reduction in the fluorescent signal primarily results from a combination of the inner filter effect (IFE) and static quenching. Additionally, these His-CuNCs were effectively utilized to identify SY within commercial food products, yielding excellent recovery percentages. To complement this, a practical visual monitoring platform utilizing smartphone technology was also developed. Ultimately, this work presents a durable, highly responsive, and streamlined approach for tracking artificial food colorings to aid in food safety protocols.

Copper nanoclusters (CuNCs) are promising fluorophores, yet their practical applications are often limited by low photoluminescence efficiency and poor environmental stability. Herein, we report an acetone-triggered strategy for constructing stable and strongly emissive L-cysteine-capped CuNC submicron assemblies (L-cys-CuNCs/AC) in water. Upon addition of a small amount of acetone, weakly emissive CuNC precursors rapidly evolved into brightly red-emissive assemblies with an emission maximum at 632 nm. Absolute photoluminescence quantum yield measurements revealed a dramatic increase from 0.11% for the precursor dispersion to 19.92% for the assembled state, confirming a substantial assembly-induced enhancement in fluorescence efficiency. Comparative experiments with other water-miscible organic solvents, including methanol, ethanol, acetonitrile, DMF, and DMSO, showed that none of them induced comparable fluorescence enhancement, highlighting the unique role of acetone in triggering the assembly process. The resulting assemblies also exhibited good storage stability in water for over 3 months. Taking advantage of the strong affinity of cyanide (CN-) toward copper species, we further developed a turn-off fluorescent sensor based on an assembly-to-disassembly process. CN--induced chemical etching led to structural disintegration of the assemblies and efficient fluorescence quenching, affording a linear response over 10-100 µM with a detection limit of 5.2 µM. The probe was successfully applied to tap water and artificial lake water samples, providing recoveries of 97.6-110.3%. This work provides a simple route for constructing highly emissive CuNC assemblies in aqueous media and demonstrates their potential for cyanide analysis in environmental water samples.

Enhanced fluorescence of copper nanoclusters based on dual-ligand engineering for sensitive detection of vitamin B12 and diosmetin in food samples.

Ratiometric copper nanocluster fluorescence probe coupled with deep learning for intelligent recognition of tetracycline antibiotics in food.

Vibrio anguillarum poses a serious threat to food safety, human health and aquaculture. At present, sensitive visual detection methods for V. anguillarum remain scarce. In this study, a novel dual-signal sensing system was constructed for the highly specific and visual detection of V. anguillarum. The system leverages loop-mediated isothermal amplification (LAMP) reaction to generate abundant AT-rich double-strand DNA products in the presence of the target pathogen. These products serve as templates for in-situ synthesis of copper nanoclusters (CuNCs), which exhibit both strong fluorescence and peroxidase-mimicking activity. The fluorescence intensity of CuNCs was positively correlated with the concentration of V. anguillarum, enabling quantitative fluorescence detection. Simultaneously, the CuNCs with peroxidase-like activity can catalyze the oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) into blue oxTMB, allowing straightforward colorimetric readout. This dual-mode approach achieved outstanding sensitivity, with detection limits as low as 18 CFU/mL for fluorescence and 108 CFU/mL for colorimetry. The system also demonstrated high specificity against related pathogenic bacteria and was successfully applied to detect V. anguillarum in real turbot samples, showing excellent recovery and reliability. Notably, a closed-vial configuration effectively minimized aerosol-derived carryover contamination, and a portable colorimetric test paper further enabled visual point-of-care analysis. This work provides a robust and versatile strategy for rapid, visual, and accurate detection of V. anguillarum, and serves as a reference for developing detection platforms for other pathogens.

Thermally activated delayed fluorescence (TADF) in metal nanoclusters (MNCs) is an effective strategy to harvest the emission from the excited-triplet states. However, the applications of these TADF-active MNCs are limited by the use of hydrophobic ligands, which generally make these MNCs insoluble. Herein, we report the NIR-TADF emitting CuNCs that are highly water-soluble and display intense-red emission in the solid state. The atomic connectivity of the CuNCs was determined by SC-XRD technique. The delayed fluorescence phenomenon is validated by temperature-dependent photoluminescence studies, and the excited singlet-triplet energy gap (ΔEST) was experimentally estimated to be ∼98 meV, thereby substantiating the TADF mechanism. DFT calculations performed on the crystal geometry of the CuNCs further attested to the TADF mechanism along with the associated charge-transfer dynamics. Additionally, the CuNCs demonstrate excellent catalytic activity involving the reduction of ferricyanide and Methylene Blue, highlighting their multifunctional applications in the aqueous phase.

Cyclodextrin-assisted L-cysteine–capped copper nanoclusters for dual detection of Hg2+ and Ag+

A new type of red-emitting copper nanoclusters (Cu NCs) was synthesized and applied to the sequential detection of multiple analytes. Remarkably, a fluorescent and colorimetric dual-mode response was achieved via a tandem reaction of the Cu NCs with hyperoxide and carboxylic acid. As a fluorescent probe, the Cu NCs were first oxidized by hyperoxide, resulting in prominent fluorescence quenching with a low detection limit (0.4 µM). Subsequently, the oxidized Cu NCs could clearly distinguish the carboxylic acid through a color change in the solution. An excellent linear relation was established between the fluorescence/absorbance intensity and the corresponding hyperoxide/formic acid concentrations. The mechanisms of fluorescence quenching and colorimetric response were investigated. Leveraging this tandem reactivity, the Cu NCs were successfully employed to identify the different oxidation degrees of 1,4-dioxane. This work provides a new strategy for the cascade detection of multiple analytes by single metal nanoclusters.

Atomically precise metal nanoclusters (APMNCs) provide an ideal platform for investigating structure-activity relationships (SARs) in catalysis. Although significant progress has been made in elucidating SARs, the development of quantitative structure-activity relationships (QSARs) in cluster catalysis─particularly those incorporating fundamental physicochemical descriptors such as Lewis acidity (LA)─remains limited and mechanistically unclear. To address this gap, we synthesized a tailored series of isostructural [X@Cu14(C24H27P)4(SCH2C6H4R)12] nanoclusters (R = OMe, CH3, H, Cl, F). Critically, this series enables exclusive modulation of LA via ligand electronic effects while maintaining identical core geometry and surface structure. Through combined experimental measurements and density functional theory (DFT) calculations of electrocatalytic hydrogen evolution reaction (HER) performance, a strong correlation within this series between LA and catalytic activity was established. A smaller LA promotes more efficient electron donation to the adsorbed hydrogen species, which lowers the reaction energy barrier and enhances HER activity. Based on this established correlation, the top-performing catalyst of [X@Cu14(C24H27P)4(SCH2C6H4OMe)12] was further optimized, enabling the design of an integrated photovoltaic-electrolysis system for water splitting. This work not only establishes LA as a meaningful electronic descriptor for nanocluster catalyst design but also demonstrates the pioneering application of APMNCs in establishing QSARs for nanocatalysis.

An organic-inorganic hybrid copper nanocluster for ratiometric fluorescence of tobramycin.

Endometriosis is a prevalent gynecologic disorder associatedwithinfertility and increased cancer risk, necessitating the developmentof sensitive and reliable diagnostic methods. Circulating microRNAs(miRNAs) have emerged as promising noninvasive biomarkers for earlydisease detection. However, low abundance and sequence similarityamong miRNA family members hinder accurate detection. Herein, we firstconducted differential expression analysis of publicly available miRNA-sequencingdata sets to identify potential diagnostic biomarkers for endometriosis,from which miR-199a-5p was selected as a representative target. Buildingon this selection, we subsequently developed a highly sensitive andspecific fluorescent biosensing platform for miR-199a-5p detectionby integrating poly­(thymine) (polyT) DNA-templated copper nanoclusters(CuNCs) with a dual isothermal amplification strategy. The biosensingsystem utilizes a 3′-phosphorylated, biotinylated hairpin DNAprobe immobilized on streptavidin-coated magnetic beads. Upon hybridizationwith the target miR-199a-5p, duplex-specific nuclease (DSN) mediatesselective cleavage, enabling target recycling and simultaneously generatinga 3′-hydroxyl terminus. This newly exposed terminus subsequentlyserves as a primer for terminal deoxynucleotidyl transferase (TdT)-catalyzedpolyT elongation. The resulting polyT sequence functions as an effectivescaffold for the in situ formation of copper nanoclusters(CuNCs), thus producing a label-free fluorescence signal within 2h. In this design, magnetic beads not only facilitate efficient separationfrom serum matrices but also enhance reaction efficiency through surface-initiatedenzymatic polymerization. As a result, the sensing platform exhibitsexcellent specificity, including reliable discrimination of single-basemismatches, and maintains robust performance in complex biologicalsamples. This integrated platform, combining bioinformatic prescreeningwith a CuNCs-based sensing strategy, offers rapid, cost-effective,and label-free detection of miRNA, showing promise for early diagnosisand clinical monitoring of endometriosis.

Wound infections, particularly surgical site infections, account for approximately 20% of all healthcare-associated infections and occur in about 2%-5% of surgical patients. Hydrogels are gaining increased prominence as antibacterial and wound healing agents. They possess a soft texture, good biocompatibility, and high water-holding capacity. In this regard, we introduce a novel chitosan (Ch)-based copper nanocluster (Cu NC)-carbon dot combination loaded hydrogel (Ch-NCCD). The Ch-NCCD hydrogel was found to be non-hemolytic against human red blood cells (RBCs) and non-toxic against mammalian cell lines. Scanning electron microscopy analysis revealed that it possesses a rough, fibrous surface with interconnected pores. Furthermore, it exhibits a moderate-to-high swelling ratio that helps it maintain a proper balance between moisture absorption and retention, and is therefore well suited for moderate exudate wounds. The Ch-NCCD hydrogel exhibits prominent antibacterial and antibiofilm activity against pathogenicPseudomonas aeruginosaPAO1. Membrane permeabilization assay through propidium iodide uptake showed that it compromised the integrity of bacterial cell membrane. Finally, in order to emphasize the real-life utility of Ch-NCCD hydrogel, we have shown that it achieves significant wound closure in male Sprague-Dawley rats within 8 d. However, in order to decipher the underlying wound healing mechanisms of Ch-NCCD, further studies combining biochemical and histological analysis are required.

Electrocatalytic carbon dioxide reduction (eCO2RR) is a promising pathway for carbon recycling and clean energy conversion, where catalyst structural engineering plays a critical role in enhancing performance. Metal nanoclusters (NCs), with their atomically precise composition, unique quantum-size effects, and tunable electronic structures, have become a key focus in eCO2RR catalyst research, where significant progress has been made. Herein, recent advances in eCO2RR using NC catalysts are reviewed. This review systematically examines the mechanisms by which the performance of metal NCs in eCO2RR can be modulated, highlighting five key factors: core size effects, single-atom modulation, ligand effects, metal doping, and support effects. The core size directly influences catalytic activity and selectivity by altering the number of active sites and electronic structures. Doping, adding, or removing single atoms enables precise control over electronic states and reaction pathways. Functional ligands optimize activity and stability by modulating the coordination environment, electron transfer, and local microenvironment. Alloying improves performance through interatomic electron transfer and structural symmetry breaking, while the use of supports enhances catalytic outcomes via physical dispersion, electronic modulation, and improved intermediate transport. Finally, recent advances are summarized, and some perspectives in this research direction are provided. This review provides insightful guidelines for the rational design of high-performance electrocatalysts and discusses the challenges and opportunities in this emerging field.

CRISPR/Cas12a-mediated marker-free fluorescent biosensing platform based on a lightful copper nanocluster for highly sensitive detection of mycotoxin.

Highly fluorescent copper nanoclusters as programmable reporters for CRISPR/Cas12a-based detection of bacterial DNA.

Zirconium-Triggered Aggregation-Induced Emission of Copper Nanoclusters for the Sensitive Fluorescent Detection of Acid Phosphatase.