Recent Advances in Near-Infrared Fluorescent Ligands as a Novel Frontier in Combating Antibiotic-Resistant Bacteria

The emergence and rapid spread of multi-drug-resistant (MDR) bacteria pose a serious and escalating threat to global public health, undermining the effectiveness of conventional antibiotics and demanding urgent development of alternative therapeutic strategies. Among these, phototherapy mediated by organic fluorescent ligands has gained increasing attention as a promising antimicrobial approach due to its spatiotemporal precision, minimal invasiveness, and reduced risk of resistance development. In phototherapeutic antimicrobial applications, near-infrared (NIR) photosensitizers are activated by light to produce reactive oxygen species (ROS) or localized heat, leading to targeted damage of bacterial membranes, proteins, and nucleic acids. This review provides a focused summary of recent advances over the past decade in the design and application of NIR organic fluorescent ligands for antibacterial phototherapy. We discuss key molecular classes which include cyclic tetrapyrroles, phenothiazinium salts, cyanine dyes, BODIPYs and aza-BODIPYs, tetraphenylethene, and triphenylamine analogues, highlighting their structural features, photophysical properties, and mechanisms of action. By consolidating these developments, our aim is to offer a comprehensive and accessible resource that supports future innovation and encourages interdisciplinary collaboration. This review contributes meaningfully to the ongoing scientific and clinical discourse on antimicrobial resistance, highlighting novel phototherapy-based solutions with potential for real-world impact.