Linseed polyol-assisted, microwave-induced synthesis of nano CuO embedded in polyol-polyester matrix: antifungal behavior and coating properties

Abstract

Nano-sized CuO particles were prepared insitu via “one-pot, solvent-less” microwave-induced synthesis, by environmentally benign polyol process using polyol obtained from Linseed oil by (non-aqueous) condensation reaction, for the first time. Linseed polyol acts as solvent, base matrix providing functional groups, and stabilizer; the reaction is devoid of any additive, catalyst or solvent. In the prepared nanocomposites [LPE-CuO], CuO nanoparticles shaped somewhat like rods, assembled themselves in a “T-fashion”. The antifungal effects of synthesized particles were investigated against four clinical isolates of different Candida species. Results showed that the synthesized compound LPE-0.06 was found to be most effective, followed by LPE-0.05 and LPE-0.04. The rapid actions of the synthesized compounds on fungal cells suggested membrane-located targets. We investigated the effect of MIC90 values of these compounds on H+-ATPase mediated proton pumping by different Candida species. In the absence of glucose, the mean inhibition rate of H+ extrusion caused by MIC of LP was 28.09%, LPE: 33.04%, CuAc: 36.86%, LPE-0.04: 58.54%, LPE-0.05: 69.82% and LPE-0.06: 78.07%, respectively. Antifungal mechanism of action suggested that the synthesized compounds exert their antifungal activity by targeting H+-ATPase mediated proton pumping. Inhibition of H+-ATPase activity leads to intracellular acidification and consequently cell death. Results obtained in this study indicated strong antifungal activity of synthesized compounds against all the Candida species and suggest that the inhibition of fungal H+ ATPase is responsible for the antifungal activity of the test compounds. LPE-CuO can be employed as antifungal polyester and polyurethane coatings. The present work is consistent with the Principles (Principle 1,2,3,4,5,6,7,8, 12) of Green Chemistry.