Green Synthesis of Antimicrobial Peptide-Protected Silver Nanoclusters with Regulated Antibacterial Behavior

Photofunctional Gold Nanocluster Composites for Bioapplications

Gold nanoclusters (AuNCs), with customized structures and diverse optical properties, are promising optical materials. Constructing composite systems by the assembly and incorporation of AuNCs can utilize their optical properties to achieve diagnostic and therapeutic applications in the biological field. Therefore, the exploration of the assembly behaviors of AuNCs and the enhancement of their performance has attracted widespread interest. In this review, we introduce multiple interactions and assembly modes that are prevalent in nanocomposites and microcomposites based on AuNCs. Then, the functions of AuNC composites for bioapplications are demonstrated in detail. These composite systems have inherited and enhanced the inherent optical performances of the AuNCs to meet diverse requirements for biological sensing and optical treatments. Finally, we discuss the prospects of AuNC composites and highlight the challenges and opportunities in biomedical applications.

Chiral Nanoclusters as Alternative Therapeutic Strategies to Confront the Health Threat from Antibiotic-Resistant Pathogens

Pseudomonas aeruginosa (P. aeruginosa), a drug-resistant Gram-negative pathogen, is listed among the "critical" group of pathogens by the World Health Organization urgently needing efficacious antibiotics in the clinics. Nanomaterials especially silver nanoparticles (AgNPs) due to the broad-spectrum antimicrobial activity are tested in antimicrobial therapeutic applications. Pathogens rapidly develop resistance to AgNPs; however, the health threat from antibiotic-resistant pathogens remains challenging. Here we present a strategy to prevent bacterial resistance to silver nanomaterials through imparting chirality to silver nanoclusters (AgNCs). Nonchiral AgNCs with high efficacy against P. aeruginosa causes heritable resistance, as indicated by a 5.4-fold increase in the minimum inhibitory concentration (MIC) after 9 repeated passages. Whole-genome sequencing identifies a Rhs mutation related to the wall of Gram-negative bacteria that possibly causes morphology changes in resistance compared to susceptible P. aeruginosa. Nevertheless, AgNCs with laevorotary chirality (l-AgNCs) induce negligible resistance even after 40 repeated passages and maintain a superior antibacterial efficiency at the MIC. l-AgNCs also show high cytocompatibility; negligible cytotoxicity to mammalian cells including JB6, H460, HEK293, and RAW264.7 is observed even at 30-fold MIC. l-AgNCs thus are examined as an alternative to levofloxacin in vivo, healing wound infections of P. aeruginosa efficaciously. This work provides a potential opportunity to confront the rising threat of antimicrobial resistance by developing chiral nanoclusters.

Multiscale Bioresponses of Metal Nanoclusters

Metal nanoclusters (NCs) are well-recognized novel nano-agents that hold great promise for applications in nanomedicine because of their ultrafine size, low toxicity, and high renal clearance. As foreign substances, however, an in-depth understanding of the bioresponses to metal NCs is necessary but is still far from being realized. Herein, this review is deployed to summarize the biofates of metal NCs at various biological levels, emphasizing their multiscale bioresponses at the molecular, cellular, and organismal levels. In the parts-to-whole schema, the interactions between biomolecules and metal NCs are discussed, presenting typical protein-dictated nano-bio interfaces, hierarchical structures, and in vivo trajectories. Then, the accumulation, internalization, and metabolic evolution of metal NCs in the cellular environment and as-imparted theranostic functionalization are demonstrated. The organismal metabolism and transportation processes of the metal NCs are subsequently distilled. Finally, this review ends with the conclusions and perspectives on the outstanding issues of metal NC-mediated bioresponses in the near future. This review is expected to provide inspiration for tailoring the customization of metal NC-based nano-agents to meet practical requirements in different sectors of nanomedicine.