N-Functionalized fluorophores: detecting urinary albumin and imaging lipid droplets

A series of novel N-sulfonyl pyridinium fluorophores were designed, synthesized, and explored in terms of their ability to bind with serum albumins. Upon binding the fluorophores with BSA, noticeable emission wavelength or intensity changes accompanied by color changes were observed. Competitive binding studies revealed that the fluorophore selectively binds to the warfarin site, but the binding affinity also depends on the nature of the scaffold. Additionally, the fluorophores were employed to detect spiked serum albumin in artificial urine. Cellular imaging experiments indicated that the fluorophores accumulate within lipid droplets (LDs), suggesting their potential as promising biomarkers for lipid droplets. Furthermore, the fluorescence intensity, number, and size of LDs increased upon serum starvation.