Hydroxypropyl methacrylamide-based copolymeric nanoparticles loaded with moxifloxacin as a mucoadhesive, cornea-penetrating nanomedicine eye drop with enhanced therapeutic benefits in bacterial keratitis

Bacterial keratitis (BK) is a leading cause of visual impairment. The fluoroquinolone antibiotic moxifloxacin (Mox), being highly water-soluble, suffers from poor corneal penetration leading to unsatisfactory therapeutic outcomes in BK. Here, we prepared Mox-loaded co-polymeric nanoparticles (NPs) by entrapping the drug in co-polymeric NPs constituted by the self-assembly of a water-soluble copolymer, poly(ethylene glycol)-b-p(hydroxypropyl) methacrylamide (mPH). The polymer (mPH) was prepared using a radical polymerization technique at different mPEG: HPMA ratios of 1:70/100/150. The polymer/nanoparticles were characterized by GPC, CAC, DLS, SEM, XRD, DSC, FTIR, % DL, % EE, and release studies. The ex vivo muco-adhesiveness and corneal permeation ability were judged using a texture analyzer and Franz Diffusion Cells. In vitro cellular uptake, cytotoxicity, and safety assessment were performed using HCE cells in monolayers, spheroids, and multilayers in transwells. The DOE-optimized colloidal solution of Mox-mPH NPs (1:150) displayed a particle size of ~116 nm, superior drug loading (8.3%), entrapment (83.2%), robust mucoadhesion ex vivo, and ocular retention in vivo (~6 h) (judged by in vivo image analysis). The non-irritant formulation, Mox-mPH NPs (1:150) (proven by HET-CAM test) exhibited intense antimicrobial activity against P. aeruginosa, S. pneumoniae, and S. aureus in vitro analyzed by live-dead cells assay, zone of inhibition studies, and by determining the minimum inhibitory and bactericidal concentrations. The polymeric nanoparticles, mPH (1:150), decreased the opacity and the bacterial load compared to the other treatment groups. The studies warrant the safe and effective topical application of the Mox-mPH NPs solution in bacterial keratitis.