Stealth polymer coatings of reactive oxygen species scavenging nanoparticles for immune response mitigation

Elevated levels of reactive oxygen species play an integral role in chronic inflammation. Current treatments for chronic inflammation often ignore reactive oxygen species and instead focus on symptom control or immunosuppression. However, by controlling reactive oxygen species in inflammatory environments, cyclic inflammation can be reduced. Combining reactive oxygen species scavenging delivery systems with stealth coatings can help avoid the innate immune system and enable targeted delivery to sites of inflammation without causing further oxidative stress. For this purpose, poly(propylene sulfide) nanoparticles were synthesized utilizing two different surfactants, Pluronic F-127 and sucrose monolaurate, adding stealth properties to the coatings of the reactive oxygen species scavenging nanoparticles. Characterization of the nanoparticles demonstrated the surfactant coatings did not affect the scavenging abilities nor the cytocompatibility of the materials. Degradation of the nanoparticles related to the sulfide groups and disulfide bond interactions with reactive oxygen species was also analyzed. Moreover, proinflammatory cytokine secretion from macrophages exposed to the nanoparticles was investigated to determine immune response evasion. Results obtained showed little to no activation of macrophages exposed to nanoparticle formulations in regard to MCP-1 cytokine release. However, there is room for improvement using glycerol-based coatings with regard to protecting cells from reactive oxygen species exposure and reducing macrophage activation in relation to IL-6 and TNF-alpha. Overall, the nanoparticles investigated have the capabilities to improve inflammatory disease treatments by not only targeting delivery of therapeutics to the site of inflammation, but also avoiding excess immune response recruitment due to incorporation of stealth coatings.