The role of ligands on synthesis, functional control, and biomedical applications of near-infrared light-responsive metal-based nanoparticles

Near-infrared light-responsive metal-based nanoparticles (NLMPs) have attracted increasing attention recently due to their unique optical properties for biomedical applications. Surface ligands play a vital role in chemical and functional control of NLMPs. However, the crucial particle-ligand and ligand-bio interactions remain poorly understood, which would hinder the tailored modification of NLMPs for flexibly controlled structural, physicochemical and functional properties. To deepen the understanding of ligand-mediated fine control over NLMPs, we aim to focus on the critical effects and mechanisms of ligands on synthesis, functional control, and biomedical applications of NLMPs. This review firstly introduces the ligand function in the synthesis, surface modification, as well as assembly/disassembly process of NLMPs. Moreover, the functional control of NLMPs by ligands to achieve enhanced sensing, imaging, and therapeutic properties is intensively elaborated. Furthermore, the representative rational designs of ligand-modified NLMPs and the related ligand-bio interactions in the diagnosis and therapy of various diseases (e.g., cancers, brain diseases, bacterial infections, cardiovascular and inflammatory diseases) are reviewed. Finally, the current challenges and future perspectives of ligand-modified NLMPs are briefly discussed.