Advanced Mucus Infiltrating Nanoparticles for Microbicide Delivery

Abstract

Advanced mucus infiltrating nanoparticles (NPs) based on ES-100 have been developed for the intravaginal delivery of Dapivirine against HIV-1. They were further surface engineered with poly ethylene glycol (PEG) that helps them overcome the mucosal barrier via enhanced pH-mediated infiltration properties. PEG coated NPs (PCN) loaded with Dapivirine was characterized for particle size distribution, morphology, loading efficiency and mucus infiltration properties. The cellular uptake profiles of PCN by human vaginal epithelial cells (VK2 E6/E7) were examined using confocal microscopy. The cytotoxicity of PCN was assessed using MTS assay as well as Annexin V-FITC/PI assays. The mucus infiltration rates of PCN were examined on the in-vitro simulated cervico-vaginal mucus system and ex vivo porcine vaginal tissues. PCN loaded with Dapivirine possessed physiochemical properties, readily traversing through mucus layer. The IR spectra of both NPs (i.e., NP uncoated but loaded with Dapivirine and PCN that were loaded with Dapivirine) did not display any additional peaks representing new functional groups, indicating there were no significant interactions among drug, PEG2000 and formulations components. The percentage yield, entrapment efficiency and loading efficacy of Dapivirine in PCN were around 75%, 64.6% and 2.03%, respectively. The micrographs of freeze dried NPs analyzed by SEM displayed smooth surface spherical particles that were previously demonstrated from the DLS study. TEM images confirmed the presence of coated PEG2000 that is supported by the difference in the zeta potential values. The results of MTS assay as well as Annexin V-FITC/PI assay demonstrated that PCN loaded with Dapivirine maintained 85% viability of human vaginal epithelial cells (VK2 E6/E7) upon exposure to the concentrations up to 0.1 mg/ml of Dapivirine in PCN. Alamar blue assay also demonstrated that cells exposed to PCN at the concentration up to 500 μg/ml were viable, indicating that PCN did not exert any cytotoxicity. The data from ensemble-averaged geometric mean square displacements confirmed that PEG2000 coating significantly enhanced the uptake rates as well as mucus penetration rates of PCN. PCN mimics two basic features of HIV-1 (i.e. capability to stay unreactive/unresponsive at acidic pH and exerting its action at neutral pH) and has achieved the enhanced mucus penetration rate. This PCN can serve as an ideal platform for vaginal delivery of Dapivirine against HIV-1.