Oligoarginine peptide structure and its effect on cell penetration in ocular drug delivery.

Oligoarginine cell-penetrating peptides (CPPs) are short peptides that can enhance drug delivery into cells and are of particular interest in ocular topical formulations for age-related macular degeneration (AMD) treatments. The length and structural characteristics of these peptides are considered crucial for drug delivery. This study investigates how oligoarginine length (Rn) affects their penetration mechanism, drug delivery capabilities, and antimicrobial properties, providing insights into their potential roles in AMD treatment delivery. In this study, oligoarginine peptides showed limited pore-forming abilities in a carboxyfluorescein-containing liposomal model, with R9 being the only oligoarginine length recording a significant pore-formation level. Their antibacterial efficacy depended on both the CPP length and bacterial class, with longer peptides exhibiting stronger antibacterial effects. Importantly, oligoarginine was found nontoxic to relevant mammalian cells for ocular delivery. The membrane translocation abilities of oligoarginine were consistent regardless of cargo presence. Additionally, cargo delivery by oligoarginine across in vitro cellular models for ocular delivery was dependent on peptide length and cell type, with longer chains being more effective at cargo uptake in a corneal epithelium cell line, and with shorter chains proving more effective for cargo delivery in a retinal epithelium cell line. This proposes that the chain length of oligoarginine could be used as a strategic tool in the formulation process to selectively target distinct regions of the eye. Overall, this study expands our understanding of how oligoarginine CPPs can be applied as penetration enhancers to improve the delivery of therapeutics in an ocular topical formulation within the clinical context of AMD.

Wettability and Bactericidal Properties of Bioinspired ZnO Nanopillar Surfaces.

Nanomaterials of zinc oxide (ZnO) exhibit antibacterial activities under ambient illumination that result in cell membrane permeability and disorganization, representing an important opportunity for health-related applications. However, the development of antibiofouling surfaces incorporating ZnO nanomaterials has remained limited. In this work, we fabricate superhydrophobic surfaces based on ZnO nanopillars. Water droplets on these superhydrophobic surfaces exhibit small contact angle hysteresis (within 2-3°) and a minimal tilting angle of 1°. Further, falling droplets bounce off when impacting the superhydrophobic ZnO surfaces with a range of Weber numbers (8-46), demonstrating that the surface facilitates a robust Cassie-Baxter wetting state. In addition, the antibiofouling efficacy of the surfaces has been established against model pathogenic Gram-positive bacteria Staphylococcus aureus (S. aureus) and Gram-negative bacteria Escherichia coli (E. coli). No viable colonies of E. coli were recoverable on the superhydrophobic surfaces of ZnO nanopillars incubated with cultured bacterial solutions for 18 h. Further, our tests demonstrate a substantial reduction in the quantity of S. aureus that attached to the superhydrophobic ZnO nanopillars. Thus, the superhydrophobic ZnO surfaces offer a viable design of antibiofouling materials that do not require additional UV illumination or antimicrobial agents.