Development of Au8 nanocluster-based fluorescent strip immunosensor for sensitive detection of aflatoxin B1.

Gold clusters with intriguing chemical/physical properties have great promise in applications such as sensing and bio-imaging due to their fascinating photoluminescence character. In this study, an immunofluorescence sensor based on levonorgestrel protected atomically precise Au8 nanocluster (Au8NC) for aflatoxin B1 (AFB1) detection was fabricated due to its strong carcinogenic and mutagenic effect on humans. The prepared polymer-Au8NC nanospheres displayed bright luminescence and good stability in aqueous solution. The obtained AFB1 fluorescent strip immunosensor achieved quantitative point-of-care detection of AFB1 in less than 15 min, with high selectivity and detection limits down to 0.27 ng/mL. In addition, the recovery rates of AFB1 from tea soup ranged from 96% to 105% with relative standard deviations less than 10%. This work not only realized high-sensitively fluorescent sensing for AFB1, but also expanded the bio-applications of atomic-precise metal clusters.

Atomic-precise Pt2Cu4 cluster-based fluorescent sensor for rapid interleukin-6 detection.

Levonorgestrel protected Pt2Cu4 clusters were assembled with a polymer to prepare nanobeads (NBs) with intense red fluorescence. An immunofluorescence sensor based on Pt2Cu4NBs was established for the rapid and sensitive detection of interleukin-6 (IL-6) owing to its significance in inflammatory diseases, with a limit of detection of 42.66 pg mL-1. IL-6 spiked in serum was also accurately detected.

Water-Soluble Au25 Clusters with Single-Crystal Structure for Mitochondria-Targeting Radioimmunotherapy.

Atomically precise gold clusters play an important role in the development of high-Z-element-based radiosensitizers, due to their intriguing structural diversity and advantages in correlating structures and properties. However, the synthesis of gold clusters with both water-solubility and single-crystal structure remains a challenge. In this study, atomically precise Au25(S-TPP)18 clusters (TPP-SNa = sodium 3-(triphenylphosphonio)propane-1-thiolate bromide) showing both mitochondria-targeting ability and water-solubility were obtained via ligand design for enhanced radioimmunotherapy. Compared with Au25(SG)18 clusters (SG = glutathione), Au25(S-TPP)18 exhibited higher radiosensitization efficiency due to its mitochondria-targeting ability, higher ROS production capacity, and obvious inhibition upon thioredoxin reductase (TrxR). In addition, the enhanced radiotherapy-triggered abscopal effect in combination with checkpoint blockade displayed effective growth inhibition of distant tumors. This work reveals the ligand-regulated organelle targeting ability of metal clusters by which feasible strategies to promote their application in precise theranostics could be realized.

Chiral gold clusters functionalized two-dimensional nanoparticle films to regulate the adhesion and differentiation of stem cells.

Chirality has been proved to play a significant role in tuning cell behaviors and controlling cellular functions. Up to now, almost all the chirality origins of extracellular microenvironment are belong to chiral ligands induction or direct chiral patterns. In this study, chiral gold nanoclusters (L/D-AuNC) loaded on two-dimensional gold nanoparticle films (L/D-film) with multiple chirality origins were prepared to regulate the adhesion and differentiation of mouse bone marrow mesenchymal stem cells (MSCs). MSCs on the D-film exhibited higher cell density and larger spreading area, and more cells differentiated into osteoblasts. Compared with D-film, L-film has a lower cell density and smaller spreading area, and more adipoblasts are achieved. The corresponding expression results of osteogenic differentiation marker (RUNX2) also confirmed the above experimental phenomenon. These results demonstrated that the chirality of clusters has great effect on the direction of cell fate.

Levonorgestrel-protected Au8 and Au10 clusters with different antimicrobial abilities.

Gold nanoclusters exhibit significant potential in antimicrobial applications due to their good stability and desirable biocompatibility in the mammalian cell model. However, most of the previously reported gold nanocluster antimicrobial agents do not have an atomic-precise structure, causing difficulties in understanding the structure-property correlation. In this study, structurally defined gold-levonorgestrel clusters, named Au8(C21H27O2)8 (Au8NCs) and Au10(C21H27O2)10 (Au10NCs), with the same ligand-to-metal ratio but different inner cores were prepared for antibacterial activity investigations, demonstrating that Au8NCs exhibited a stronger antibacterial activity owing to the more significant damage it causes on the bacteria wall and membrane, and a stronger inhibition of glutathione reductase activity in bacteria. The leakage of the intracellular components and enzyme inhibition caused an imbalance of the intracellular antioxidant defence system, and consequently killed bacteria. These results indicated that the structure of gold nanoclusters has an important effect on their biological activity, indicating that it as a key factor to consider in the future design of antimicrobial agents.

Composition-Dependent Enzyme Mimicking Activity and Radiosensitizing Effect of Bimetallic Clusters to Modulate Tumor Hypoxia for Enhanced Cancer Therapy.

Alloying is an efficient chemistry to tailor the properties of metal clusters. As a class of promising radiosensitizers, most previously reported metal clusters exhibit unitary function and cannot overcome radioresistance of hypoxic tumors. Here, atomically precise alloy clusters Pt2 M4 (M = Au, Ag, Cu) are synthesized with bright luminescence and adequate biocompatibility, and their composition-dependent enzyme mimicking activity and radiosensitizing effect is explored. Specifically, only the Pt2 Au4 cluster displays catalase-like activity, while the others do not have clusterzyme properties, and its radiosensitizing effect is the highest among all the alloy clusters tested. By taking advantage of the sustainable production of O2 via the decomposition of endogenous H2 O2 , the Pt2 Au4 cluster modulates tumor hypoxia as well as increases the efficacy of radiotherapy. This work thus advances the cluster alloying strategy to produce multifunctional therapeutic agents for improving hypoxic tumor therapy.