FA1 site-targeted fluorescent probe for HSA detection and labeling: Biomedical applications and MD insights into local conformational perturbation.

The accurate detection of human serum albumin (HSA) and the tracing of its associated drug delivery systems hold critical significance for clinical disease diagnosis and precision tumor therapy. To develop high-performance HSA fluorescent probes, NHP was successfully synthesized, which exhibits exceptional selectivity, anti-interference capability, and detection sensitivity. Molecular dynamics simulations and molecular docking revealed that NHP specifically binds to the FA1 site, triggering localized alterations in protein dynamics and a modest reduction in Arg solvent exposure. Complementary spectroscopic and SDS-PAGE assays further demonstrated that NHP binding markedly enhances HSA's resistance to tryptic degradation. Biological assays verified NHP's ultra-low cytotoxicity, preferential lysosomal colocalization, and precise discrimination between tumor cells and normal cells. Additionally, NHP achieved sensitive HSA detection in urine and enabled visual tracking of albumin-loaded platinum-based drugs. The multifunctional fluorescent probe provides an efficient in-vitro tool for HSA detection and labeling, exhibiting promising research value for preliminary exploration of urinary albumin-related studies, tumor fluorescence imaging, and drug delivery monitoring.