Promoting photothermal antibacterial activity through an excited-state intramolecular proton transfer process

The Key Role of Molecular Packing in Luminescence Property: From Adjacent Molecules to Molecular Aggregates

The luminescence materials act as the key components in many functional devices, as well as the detection and imaging systems, which can be permeated in each aspect of modern life, and attract more and more attention for the creative technology and applications. In addition to the diverse properties of organic luminogens, the multiple molecular packing at aggregated states frequently offers new and/or exciting performance. However, there still lacks comprehensive analysis of molecular packing in these organic materials, resulting in an increased gap between molecular design and practical applications. In this review, from the basic knowledge of organic compounds as single molecules, to the discernable property of excimer, charge transfer (CT) complex or self-assembly systems by adjacent molecules, and finally to the opto-electronic performance of molecular aggregates, the relevant factors to molecular packing and practical applications are discussed.

Trends in Photothermal Nanostructures for Antimicrobial Applications

The rapid development of antimicrobial resistance due to broad antibiotic utilisation in the healthcare and food industries and the non-availability of novel antibiotics represents one of the most critical public health issues worldwide. Current advances in nanotechnology allow new materials to address drug-resistant bacterial infections in specific, focused, and biologically safe ways. The unique physicochemical properties, biocompatibility, and wide range of adaptability of nanomaterials that exhibit photothermal capability can be employed to develop the next generation of photothermally induced controllable hyperthermia as antibacterial nanoplatforms. Here, we review the current state of the art in different functional classes of photothermal antibacterial nanomaterials and strategies to optimise antimicrobial efficiency. The recent achievements and trends in developing photothermally active nanostructures, including plasmonic metals, semiconductors, and carbon-based and organic photothermal polymers, and antibacterial mechanisms of action, including anti-multidrug-resistant bacteria and biofilm removal, will be discussed. Insights into the mechanisms of the photothermal effect and various factors influencing photothermal antimicrobial performance, emphasising the structure-performance relationship, are discussed. We will examine the photothermal agents' functionalisation for specific bacteria, the effects of the near-infrared light irradiation spectrum, and active photothermal materials for multimodal synergistic-based therapies to minimise side effects and maintain low costs. The most relevant applications are presented, such as antibiofilm formation, biofilm penetration or ablation, and nanomaterial-based infected wound therapy. Practical antibacterial applications employing photothermal antimicrobial agents, alone or in synergistic combination with other nanomaterials, are considered. Existing challenges and limitations in photothermal antimicrobial therapy and future perspectives are presented from the structural, functional, safety, and clinical potential points of view.