Razi University

Abstrac This thesis is contained two parts. Part I is about cadmium(II) complex and Part II is about ZnO nanoparticles (ZnO  ). In Part I, a novel cadmium(II) complex containing naproxen and 1,10-phenanthroline ligands was synthesized and fully characterized using spectroscopic techniques. The biomolecular interactions of the complex with calf thymus DNA (CT-DNA) and human serum albumin (HSA) were systematically investigated through UV-Vis absorption, fluorescence spectroscopy, circular dichroism (CD), and molecular docking studies. Spectroscopic analyses revealed that the interaction between the complex and HSA is strong, spontaneous, and predominantly enthalpy-driven. Fluorescence quenching followed a static mechanism, as evidenced by decreasing binding constants with increasing temperature. Thermodynamic parameters (?H° < 0 and ?S° < 0) indicated that hydrogen bonding and other specific non-covalent interactions play a major role in the binding process. Competitive site marker experiments suggested that the complex preferentially binds to Sudlow’s site II, inducing partial conformational changes in the protein structure, as confirmed by CD measurements. Molecular docking further supported these findings, locating the complex within subdomains IIIA and IIIB of HSA and revealing multiple hydrogen bonding, electrostatic, and hydrophobic interactionsIn Part II, zinc oxide nanoparticles (ZnO  ) were synthesized via a green approach using Lippia citriodora extract as a natural reducing and stabilizing agent, followed by loading of naproxen to obtain a ZnO  –Nap nano-drug system. The structural and morphological properties of the synthesized nanoparticles were characterized using UV–Vis spectroscopy, FT-IR, FE-SEM, and AFM analyses. The results confirmed the successful formation of ZnO   with an average particle size of approximately 29 nm, which increased to around 35 nm after drug loading, indicating effective incorporation of naproxen onto the nanoparticle surface. The interaction of ZnO  –Nap with biomacromolecules, including human serum albumin (HSA) and calf thymus DNA (CT-DNA), was systematically investigated using UV–Vis absorption and fluorescence spectroscopy. Fluorescence quenching studies revealed a static quenching mechanism in the presence of HSA, indicating stable complex formation between the nano-drug and the protein. Thermodynamic parameters suggested that the binding process is spontaneous and mainly governed by hydrophobic interactions. Similarly, interaction studies with CT-DNA demonstrated moderate binding affinity, as evidenced by hypochromic effects in UV–Vis spectra and fluorescence quenching behavior. Binding constant analysis indicated the presence of approximately one binding site per DNA molecule.