1H-NMR analysis of fluoroquinolone (pyridopyrrole quinoxaline, PPQ) conjugated to gold nanoparticles for synergistic anticancer drug design

Abstract

The tethering mechanism between Pyrido Pyrrole Quinoxaline (PPQ) anticancer agent and gold nanoparticles (AuNPs) to form the PPQ/AuNPs complex as a promising anticancer reagent was investigated. Physicochemical properties, including viscosity, self-diffusion coefficients, and local molecular dynamics, of both PPQ and the PPQ/AuNPs complex were systematically examined using advanced techniques such as high-resolution 1H Nuclear Magnetic Resonance (1H-NMR), spin-lattice relaxation time (T1), and self-diffusion coefficient (D) analysis. Various PPQ/AuNPs systems were prepared and analyzed, encompassing concentrations of 0, 1.5, 4, 6.5, 8.3, 10.15, and 11.15 mg of PPQ. The results of T1demonstrated that the predominant intermolecular bonding occurs between AuNPs and fluorine atoms, particularly involving the neighboring proton to the fluorine and nitrogen atoms. Remarkably, the curve of self-diffusion coefficients displayed notable peaks at PPQ concentrations of approximately 4 mg and 8.3 mg. The interaction between PPQ molecules and AuNPs revealed a pronounced affinity for the fluorine sites and hydrogen atoms within the hydroxyl group of PPQ molecules when dissolved in aqueous solutions.