Quercetin encapsulation in modified silica nanoparticles: potential use against Cu(II)-induced oxidative stress in neurodegeneration.

Neurodegenerative diseases entail deeply complex processes, intimately associated with progressive brain damage reflecting cellular demise. Biochemical reactivity linked to such processes in Alzheimer's disease involves, among others, metal-induced oxidative stress contributing to neuronal cell death. Prominent among redox active metals inducing oxidative stress is Cu(II). Poised to develop molecular technology counteracting oxidative stress, efforts were launched to prepare bioactive hybrid nanoparticles, capable of working as host-carriers of potent antioxidants, such as the natural flavonoid quercetin. Employing synthetic protocols consistent with the assembly of silica nanoparticles, PEGylated and CTAB-modified materials were synthesized. Subsequent concentration-dependent loading of quercetin led to well-defined molecular carriers, the antioxidant efficiency of which was determined through drug release studies using UV-visible spectroscopy. The physicochemical characterization (elemental analysis, particle size, z-potential, FT-IR, thermogravimetric analysis, scanning electron microscopy) of the empty and loaded silica nanoparticles led to the formulation of optimized material linked to the delivery of the encapsulated antioxidant to primary rat hippocampal cultures under oxidative stress. Entrapment and drug release studies showed a) the competence of hybrid nanoparticles as far as the loading capacity in quercetin (concentration dependence), b) congruence with the physicochemical features determined, and c) the release profile of the nanoparticle load under oxidative stress in neuronal cultures. The bio-activity profile of quercetin nanoparticles in a neurodegenerative environment brought on by Cu(II) a) denotes the improved specificity of antioxidant reactivity counteracting oxidative stress, and b) sets the stage for the development of molecular protection and preventive medical nanotechnology of relevance to neurodegenerative Alzheimer's disease.