Near-infrared-responsive antibacterial nanomaterials: NIR-I Vs. NIR-II.

Bacterial infections, particularly those associated with drug-resistant bacteria and biofilms, have emerged as a major challenge to global public health. Near-infrared (NIR)-responsive antibacterial nanomaterials offer unique advantages in anti-infective therapy due to their non-invasiveness, spatiotemporal controllability, and ability to integrate multiple functions. Depending on the excitation wavelength, NIR is typically divided into two windows: NIR-I (700-900 nm) and NIR-II (1000-1700 nm). Although both share fundamental antibacterial mechanisms such as photothermal therapy, photodynamic therapy, and synergistic multimodal effects, they differ significantly in tissue penetration depth, energy deposition patterns, material construction strategies, and suitability for various infectious scenarios. This review systematically summarizes the mechanisms, major material systems, and research progress of NIR-I and NIR-II responsive antibacterial nanomaterials for applications including drug-resistant bacterial infections, biofilm eradication, deep-seated infection intervention, and theranostics. Special emphasis is placed on comparing the two platforms in terms of treatment depth, reactive oxygen species (ROS) generation capacity, imaging performance, and clinical translation potential. Overall, the NIR-I platform, characterized by mature technology and a wide variety of material systems, is more suitable for treating superficial infections. In contrast, the NIR-II platform, owing to its deeper tissue penetration and superior imaging capabilities, holds greater promise for precision treatment and theranostics of deep-seated infections. Finally, this review discusses current challenges in the field regarding material safety, standardized evaluation, and clinical translation, and offers perspectives on future directions.