Investigating the Serum Albumin Binding Behavior of Naphthalimide Based Fluorophore Conjugates: Spectroscopic and Molecular Docking Approach

In the present study, naphthalimide-pyrazole-benzothiazole based fluorescent analogs were synthesized by substituting different primary and secondary amines on the naphthalimide nucleus and were evaluated for their sensitivity and selectivity towards serum albumin. Among various synthesized analogues compound 25 showed the most significant change with serum albumin and was further studied for selective detection and mode of interaction with serum albumin. Here, we compared the binding interaction of fluorescent probe 25 for variation/detection of two 76 % structurally resembling proteins HSA and BSA, by spectroscopic experiments. The compound shows more selectivity for HSA and BSA with a higher binding constant and evident visible change in the emission spectra of two serum albumins among different bioanalytes. The mode of interaction of 25 with human serum albumin and bovine serum albumin was investigated by FT-IR, circular dichroism, and DLS techniques to find out the change in the microenvironment and variation in the structure of serum albumin proteins. Higher binding affinity and specific selectivity of 25 with a limit of detection of 0.69 mu M and 1.4 mu M towards HSA and BSA compared to other bioanalytes make it a significant fluorescent probe for quantitatively detecting serum albumins at the very early stage of many fatal diseases. This work elucidates design and synthesis of novel naphthalimide-pyrazole-benzothiazole-based fluorophore for sensitive and selective detection of serum albumin proteins (HSA and BSA). The compound substituted with N,N-diethylenediamine appears to be the most significant fluorophore with high selectivity for serum albumin proteins over different bioanalytes having LOD of 0.69 mu M and 1.4 mu M for HSA and BSA, respectively. image