Structural Impact of Anthracene-Appended Mn-MOF on Human Serum Albumin and Its Cellular Implications

Metal-organic frameworks (MOFs) are gaining attention as multifunctional nanomaterials for biomedical applications due to their porosity, tunable structure, and potential for molecular-level imaging. In this study, we synthesized green-emitting, water-dispersible manganese-based MOF (Mn-MOF) nanoparticles for live-cell imaging and investigated their interactions with human serum albumin (HSA). Spectroscopic analyses revealed high-affinity binding, with fluorescence quenching constants in the range of 10¹³. A red shift in emission and circular dichroism data confirmed that HSA retained its native conformation, underscoring the structural compatibility of Mn-MOFs. Biocompatibility was assessed using HeLa, A549, and chondrocyte cell lines. Cytotoxicity assays showed high cell viability at moderate concentrations and early time points. Nanoparticle size (∼18 nm by DLS; <10 nm by TEM) likely facilitated cellular uptake while minimizing toxicity. Confocal microscopy and flow cytometry revealed efficient internalization via multiple endocytic pathways, with perinuclear localization and no significant morphological changes. However, higher concentrations decreased cell adhesion and viability, indicating a dose-dependent toxicity threshold. These results demonstrate that Mn-MOF nanoparticles maintain protein integrity and exhibit low cytotoxicity, supporting their potential as safe, effective platforms for live-cell imaging and targeted delivery in nanomedicine.