Study of drugs and biologically active fluorophores in different biomimetic systems

Abstract

In the past decades, there is burgeoning interest in understanding the properties of systems that arise out of the interactions of biomolecules. Thus the importance of organized assemblies which act as biomimetic systems in biological and photophysical/photochemical processes, have been considerably recognized. Reactants confined in molecular assemblies such as micelles, reverse micelles, microemulsion and vesicles etc. offer a greater degree of organization compared to their geometries in homogeneous solution. They can mimic reactions in biosystems and also have great potential to act as a host system for several organic molecules which includes important drug molecules. Since the local properties e.g. polarity, viscosity, and pH in such a nanoenvironment are vastly different from those in a bulk medium, the structure, dynamics, and reactivity of biomolecules at an interface differ markedly from those observed in the bulk. Interestingly, most natural and biological processes occur at such interfaces or in confined systems, e.g., proteins, biomembranes, and vesicles.Therefore, chemistry, in organized assemblies, mimics the extremely efficient chemical processes occurring in the natural systems. The wide range of functions performed by biological membranes and membrane proteins have motivated the researchers to look for simple model systems that can mimic, at least in part, the physicochemical properties of the membrane architecture. Because of the widespread interest, the study of different kinds of organized assemblies has grown enormously over the last decade and it has become virtually impossible to summarize all the new results in a single article. Studies on the supramolecular interactions of drugs with various biological targets, are of immense importance for the perception of structural and functional features of biomacromolecules, so as to simulate the biophysical processes. This leads to a widespread interest in studying the spectroscopic and photophysical properties of fluorescent molecules in different organized media for a better understanding of the solubilization site and interaction in true biological systems. Therefore, we have undertaken entrapment of various fluorophores in different biomimetic systems and studied the photodynamical and photophysical behavior of those complexes. The various biomimetic systems studied in this thesis are bile salt aggregates, reverse micelles, liposome-bile salt aggregates, proteins and liposomes-proteins complex. We used two fluoroquinolone drug molecules namely Norfloxacin and Ofloxacin and an anticancer drug molecule namely Ellipticine and exploited their photophysical properties to understand their interaction with biological systems.