Addressing the Exigent Role of a Coumarin Fluorophore toward Finding the Suitable Microenvironment of Biomimicking and Biomolecular Systems: Steering to Project the Drug Designing and Drug Delivery Study

Sandip Paul; Pritam Roy; Sourav Das; Soumen Ghosh; Pinki Saha Sardar; Anjoy Majhi

doi:10.1021/acsomega.0c06152

Addressing the Exigent Role of a Coumarin Fluorophore toward Finding the Suitable Microenvironment of Biomimicking and Biomolecular Systems: Steering to Project the Drug Designing and Drug Delivery Study

ACS Omega. 2021 Apr 22;6(18):11878-11896. doi: 10.1021/acsomega.0c06152. eCollection 2021 May 11.

Authors

Sandip Paul¹, Pritam Roy², Sourav Das³, Soumen Ghosh³, Pinki Saha Sardar⁴, Anjoy Majhi¹

Affiliations

¹ Department of Chemistry, Presidency University, 86/1 College Street, Kolkata 700 073, India.
² Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India.
³ Centre for Surface Science, Physical Chemistry Section, Department of Chemistry, Jadavpur University, Kolkata 700032, West Bengal, India.
⁴ Department of Chemistry, The Bhawanipur Education Society College, Kolkata 700020, India.

Abstract

The photophysics of 4-azidocoumarin (4-AC), a novel fluorescent coumarin derivative, is well established by the investigation of the alteration of the microheterogeneous environment comprising two types of systems: supramolecular systems, cyclodextrins (CDs), and biomolecular systems, serum albumins (SAs). The enhanced emission of the ligand with the organized assemblies like α-CD, β-CD, and γ-CD by steady-state and time-resolved fluorescence and fluorescence anisotropy at 298 K is compared with those of bovine serum albumin (BSA) and human serum albumin (HSA). The remarkable enhancement of the emission of ligand 4-AC along with the blue shift of the emission for both the systems are visualized as the incorporation of 4-AC into the hydrophobic core of the CDs and proteins mainly due to reduction of nonradiative decay process in the hydrophobic interior of CDs and SAs. The binding constants at 298 K and the single binding site are estimated using enhanced emission and anisotropy of the bound ligand in both the systems. The marked enhancement of the fluorescence anisotropy indicates that the ligand molecule experiences a motionally constrained environment within the CDs and SAs. Rotational correlation time (θ_c) of the bound ligand 4-AC is calculated in both the categories of the confined environment using time-resolved anisotropy at 298 K. Molecular docking studies for both the variety of complexes of the ligand throw light to assess the location of the ligand and the microenvironment around the ligand in the ligand-CD and ligand-protein complexes. Solvent variation study of the probe 4-AC molecule in different polar protic and aprotic solvents clearly demonstrates the polarity and hydrogen-bonding ability of the solvents, which supports the alteration of the microenvironments around 4-AC due to binding with the biomimicking as well as biomolecular systems. Dynamic light scattering is employed to determine the hydrodynamic diameter of free BSA/HSA and complexes of BSA/HSA with the ligand 4-AC.