A self-assembled nanoprobe for detecting HSA based on hydrazide Schiff base: Its applications in diseases diagnosis and lysosome targeting imaging

Human serum albumin (HSA) is considered to be a diagnostic index of numerous diseases, and detecting HSA in subcellular environments is of great importance. In this work, we successfully synthesized a fluorescent probe NDIC based on hydrazide Schiff base, which can self-assemble into nanospheres in aqueous solution and produce distinct fluorescence signal in the presence of HSA. NDIC showed advantages including good sensitivity (LOD = 8.44 nM), high selectivity and anti-interference (over different coexisting proteins, amino acids, cations and anions). Job's plot, CD spectra, HSA destruction, site binding replacement and molecular docking provided reliable evidence for the fact that NDIC could combine at drug site I of HSA. Non-toxic probe NDIC could be applied to quantitatively detect HSA contents in urine, and achieve cancer identification by HSA imaging in cancer cells. More importantly, successful confocal experiment proved that NDIC possessed the lysosome selective imaging ability with the aid of HSA. These results showed the probe NDIC met the requirements of biological applications and was expected to explore HSA at the subcellular levels.