CTAB-PLGA Curcumin Nanoparticles: Preparation, Biophysical Characterization and Their Enhanced Antifungal Activity against Phytopathogenic FungusPythium ultimum

In the current study, we utilized application of nanotechnological advancements to synthesize positively charged curcumin nanoparticles (CurNPs). In CurNPs, curcumin (Cur) was encapsulated by a stabilizer, polymer poly(lactic-co-glycolic acid) (PLGA) and its surface charge was modified by cationic surfactant cethyltrimetylammonium bromide (CTAB). Characterization methods involving UV-visible spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM) and dynamic light scattering (DLS) were employed to confirm their synthesis. Then, we used CurNPs to investigate their potential as fungicidal agentsin vitroand the underlying mechanisms, as compared to free Cur in the two fungal strains SR1 and BP1120 of a destructive plant pathogenPythium ultimumvar. ultimum. The fungicidal activity of CurNPs were studied by several methods which resulted in comparatively more pronounced antifungal activity in BP1120 than SR1. Broth dilution and well diffusion assay revealed minimum inhibitory concentration (MIC80) for CurNPs to be 52.57 mu g/mL and 44.67 mu g/mL and an increase in zone of inhibition (ZOI) by 5.4 and 6.3 fold of Cur at 15 mu g/mL of CurNPs in SR1 and BP1120, respectively. Study of growth curve showed prolonged lag phase, delayed and short log phase, early and prolonged stationary phase and early decline phase after CurNPs exposure. Toxicity of CurNPs in SR1 and BP1120 strains ofP. ultimumwas attributed to the enhancement in intracellular reactive oxygen species (ROS) generation and fall in mitochondrial membrane potential (MMP) as revealed by spectrofluorometric assay. Taken together, these CurNPs were confirmed as a novel and very potent fungicidal agents againstP. ultimumvar. ultimumwith a great promise of controlling and treating other microbial infections.