Antimicrobial and\nAntioxidant Properties of Photodegraded\nAmorphous Curcumin on Silica Nanoparticles

This work utilizes the concept of curcumin amorphization\nto improve\ndrawbacks currently found if it is used as a pharmaceutical ingredient,\nsuch as low solubility, limited bioavailability, and absorption, by\nanchoring it with silica nanoparticles (SiO<sub>2</sub>NP). Curcumin\nloading was determined following kinetic and adsorption parameters,\nresulting in more than 70% of the curcumin being loaded onto nanoparticles\nafter 180 min. The adjusted data resulted in a Langmuir and BET best-fit\nwith a coefficient relating to favorable adsorption and a multilayer\nmechanism. With a reduction of more than 70% of the particle area\nafter curcumin loading, it increased the SiO<sub>2</sub>NP size. Due\nto curcumin, FTIR data presented a free unbounded vibration of SiO<sub>2</sub>NP, disappearing in favor of a chemical reaction. The XRD\npattern showed complete amorphization of curcumin after loading, resulting\nin a drug release under ethanol of up to 41% in 30 days. To improve\nthis, photodegradation on SiO<sub>2</sub>NP with curcumin was performed,\nshowing a vast improvement of the antioxidant activity (ABTS and DPPH)\nafter 72 h, related to the degradation products that were hydrophilic\nbut still lower than pure curcumin, demonstrating the protection effect\nof SiO<sub>2</sub>NP. These led to an increase in antimicrobial potential\nagainst fungus and Gram-negative and Gram-positive bacteria when anchored\nand photodegraded, related to their depolymerization. Docking studies\nwere conducted to assess the antibacterial effect, revealing that\nthe conjugated double bond, a common region for photolysis, remains\nprominent, even when curcumin is anchored. Interestingly, anchoring\ncurcumin with nanosilica enhances the efficacy, potentially attributed\nto its antioxidant ability. By anchoring curcumin on nanosilica and\nperforming posterior photolysis, enhanced benefits were achieved by\nproviding support for the degraded products to act in targeted applications\nsuch as cancer that can promote stable drug release.