Green-Engineered PEI/PVA-Functionalized Silk Fibroin Nanoparticles for Heat-Stable Delivery of Clitoria ternatea L. Anthocyanins: Formulation, Characterization, and Sustainability Assessment.

Anthocyanins, natural antioxidants found in Clitoria ternatea L. flowers, exhibit instability when exposed to high temperatures. Therefore, to heat-protect the anthocyanins, this investigation produced C. ternatea extract-loaded polymeric (polyethylenimine (PEI) or poly-(vinyl alcohol) (PVA)) functionalized silk fibroin nanoparticles using a green/sustainable process. The nanoparticles were effectively generated using a simple green one-pot desolvation method with simple ingredient mixing, with entrapment efficiencies (>80%), nanosizes (200-800 nm), spherical shapes, and appropriate chemical interactions. Using the standard 2,2-diphenyl-1-picrylhydrazyl (DPPH) antioxidant method, the C. ternatea flower extract possessed an IC(50) of 0.46 ± 0.09 μg/mL, which was much better than that of standard ascorbic acid (3.94 ± 0.48 μg/mL). The nanoparticles exhibited excellent antioxidant activity (0.65 ± 0.12 μg/mL), comparable to that of the free extract. Interestingly, as analyzed by differential scanning calorimetry, the extract was efficiently protected under high-temperature conditions by being encapsulated in the nanoparticle system. After 4 h of incubation at 70 °C, the DPPH scavenging efficiency of the extract-loaded nanoparticles was ∼85%, whereas that of the free extract was only ∼17%. In addition, the sustainability and environmental impacts of the formulation process were assessed using life cycle assessment (LCA), which showed that our green method was not harmful to the environment in terms of all critical aspects of ecotoxicity, acidification, and, especially, climate change. In conclusion, the polymeric functionalized fibroin nanoparticles could be a potential system for protecting encapsulated drugs/extracts, and the novel one-pot green process for nanoparticle formulation could provide insights for future research.