Differential recognition and quantification of HSA and BSA based on two red-NIR fluorescent probes

Two red-NIR fluorescence probes, BI-FPI and NTPS-FPI, were developed for the differentiable recognition of HSA and BSA. BI-FPI showed the remarkable selectivity and high sensitivity toward HSA over BSA. BI-FPI located within site I of HSA, which mainly depended on the hydrophobic residues and π-π interaction. The linear response of the fluorescence gave a low detection limit (0.01 μM, 0.66 mg/L) to HSA. On the contrary, NTPS-FPI exhibited a significant selectivity to BSA. It docked into the interface between subdomains II and IIIA of BSA with strong hydrogen bonding interaction, and the quantitative detection limit was 0.03 μM (2.04 mg/L).228