Near-infrared squaraine dye as a selective protein sensor based on self-assembly

Proteins are among the pivotal constituents in living systems. The development of fluorescent probes with appropriate selectivity and sensitivity at biologically relevant signaling levels offers opportunities to explore their roles in physiological functions. Here we report the design and synthesis of a new squaraine based fluorescent molecule SQ1 and the study of its sensing interaction with bovine serum albumin (BSA). The interaction of SQ1 with BSA was investigated by fluorescence and UV-vis absorption spectroscopy. Displacement studies were carried out with site selective probes to locate the binding site, showing that the SQ1 binds at site I. The results obtained from the docking studies are also in good agreement with the experimental results. The SQ1cBSA was used for cell incubation and in vitro fluorescence imaging studies. (C) 2017 Elsevier B.V. All rights reserved.