A novel furo[3,2-c]pyridine-based AIE photosensitizer for specific imaging and photodynamic ablation of Gram-positive bacteria

Photoactive rhodamine-based photosensitizer eliminates Staphylococcus aureus via superoxide radical photosensitization

Due to the antibiotics abuse, bacterial infection has become one of the leading causes of human death worldwide. Novel selective antimicrobial agents are urgently needed, with the hope of maintaining the balance of the microbial environment. Photo-activated chemotherapeutics have shown great potential to eliminate bacteria with appealing spatiotemporal selectivity. In this work, we reported the structural modification to enhance the triplet excited state property of Rhodamine B, synthesizing a rhodamine-based photosensitizer RBPy. Upon light activation, RBPy exhibited much stronger photosensitization ability than the parent compound Rhodamine B both in solution and in bacteria. Importantly, RBPy can selectively inactivate Staphylococcus aureus and inhibit biofilm formation with high biocompatibility. This work provides a new strategy to develop rhodamine-based photoactive chemotherapeutics for antimicrobial photodynamic therapy.

Type I Photosensitizer Targeting Glycans: Overcoming Biofilm Resistance by Inhibiting the Two-Component System, Quorum Sensing, and Multidrug Efflux

Stubborn biofilm infections pose serious threats to human health due to the persistence, recurrence, and dramatically magnified antibiotic resistance. Photodynamic therapy has emerged as a promising approach to combat biofilm. Nevertheless, how to inhibit the bacterial signal transduction system and the efflux pump to conquer biofilm recurrence and resistance remains a challenging and unaddressed issue. Herein, a boric acid-functionalized lipophilic cationic type I photosensitizer, ACR-DMP, is developed, which efficiently generates •OH to overcome the hypoxic microenvironment and photodynamically eradicates methicillin-resistant Staphylococcus aureus (MRSA) and biofilms. Furthermore, it not only alters membrane potential homeostasis and osmotic pressure balance due to its strong binding ability with plasma membrane but also inhibits quorum sensing and the two-component system, reduces virulence factors, and regulates the activity of the drug efflux pump attributed to the glycan-targeting ability, helping to prevent biofilm recurrence and conquer biofilm resistance. In vivo, ACR-DMP successfully obliterates MRSA biofilms attached to implanted medical catheters, alleviates inflammation, and promotes vascularization, thereby combating infections and accelerating wound healing. This work not only provides an efficient strategy to combat stubborn biofilm infections and bacterial multidrug resistance but also offers systematic guidance for the rational design of next-generation advanced antimicrobial materials.

Nanozyme-Based Supramolecular Self-Assembly As an Artificial Host Defense System For Treatment of Bacterial Infections

The proper functioning of host defense system (HDS) is the key to combating bacterial infection in biological organisms. However, the delicate HDS may be dysfunctional or dysregulated, resulting in persistent infection, tissue damage, or delayed wound healing. Herein, a powerful artificial "host defense system" (aHDS) is designed and constructed for treatment of bacterial infections. First, the aHDS can quickly trap the bacteria by electrostatic interactions. Next, the system can be stimulated to produce large amounts of cytotoxic reactive oxygen species (ROS) and exert strong antibacterial effects, which can further regulate the immune microenvironment, leading to macrophage polarization from M0 to pro-inflammatory phenotype (M1) for synergistic bacteria killing. At the later stages, the system can exhibit excellent antioxidant enzyme-like activities to reprogram the M1 macrophage to anti-inflammatory phenotype (M2) for accelerating wound healing. This powerful aHDS can effectively combat the bacteria and avoid excessive inflammatory responses for the treatment of bacteria-infected wounds.

Mitochondria-targeting NIR AIEgens with cationic amphiphilic character for imaging and efficient photodynamic therapy

A new dual-cationic amphiphilic AIEgen TPhBT-PyP with NIR emission and efficient ¹O₂ generation was designed. The amphiphilicity of TPhBT-PyP was tuned with dual-positive charges of pyridinium and TPP groups, efficiently targeting mitochondria and distinguishing Gram-positive bacteria. TPhBT-PyP performed well in photodynamic therapy, inducing cancer cell apoptosis and killing S. aureus bacteria.