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.

Developing Novel Biointerfaces: Using Chlorhexidine Surface Attachment as a Method for Creating Anti-Fungal Surfaces.

There is an increasing focus in healthcare environments on combatting antimicrobial resistant infections. While bacterial infections are well reported, infections caused by fungi receive less attention, yet have a broad impact on society and can be deadly. Fungi are eukaryotes with considerable shared biology with humans, therefore limited technologies exist to combat fungal infections and hospital infrastructure is rarely designed for reducing microbial load. In this study, a novel antimicrobial surface (AMS) that is modified with the broad-spectrum biocide chlorhexidine is reported. The surfaces are shown to kill the opportunistic fungal pathogens Candida albicans and Cryptococcus neoformans very rapidly (<15 min) and are significantly more effective than current technologies available on the commercial market, such as silver and copper.

Stability of Cell-Penetrating Peptide anti-VEGF Formulations for the Treatment of Age-Related Macular Degeneration.

AIM: The development of a polyarginine cell-penetrating peptide (CPP) could enable the treatment of age-related macular degeneration, with drugs like bevacizumab, to be administered using eye drops instead of intravitreal injections. Topical formulations have a vast potential impact on healthcare by increasing patient compliance while reducing the financial burden. However, as the ocular preparations may contain several doses, it is essential to understand the stability of the bevacizumab+CPP conjugate produced. MATERIALS AND METHODS: In this work, we examine the stability of a bevacizumab solution with and without cell-penetrating peptide using dynamic light scattering and circular dichroism to assess the physical stability. We use HPLC to assess the chemical stability and ELISA to assess its biological activity. We also examine the potential of the CPP to be used as an antimicrobial agent in place of preservatives in the eye drop. RESULTS: The structural stability of bevacizumab with and without the CPP was found not to be affected by temperature: samples stored at either 20°C or 4°C were identical in behavior. However, physical instability was observed after five weeks, leading to aggregation and precipitation. Further investigation revealed that the addition of the polypeptide led to increased aggregation, as revealed through dynamic light scattering and concentration analysis of the peptide through HPLC. Complexing the bevacizumab with CPP had no effect on biological stability or degradation. CONCLUSIONS: Our findings suggest that the shelf life of CPP+bevacizumab complexes is at least 38 days from its initial formulation. Currently, the mechanism for aggregation is not fully understood but does not appear to occur through chemical degradation.

Directly bonding antimicrobial peptide mimics to steel and the real world applications of these materials.

Despite increased sterilisation and education campaigns, hospital acquired infections have not been eradicated. Bacterial colonisation of frequent touch surfaces is key in the transmission of infection. Most current technologies cannot provide a material which can rapidly kill bacteria. Here we report a novel surface technology, which uses synthetic mimetics of human defensin proteins on a surface. The surface shows excellent antibacterial efficacy against Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus, Pseudomonas aeruginosa and Escherichia coli. Both microbiology laboratory tests and trials in hospital settings of this new antimicrobial material (AMS) showed >99% efficacy over a year in situ. It maintains its efficacy through accelerated ageing tests and has shown to kill bacteria far more rapidly (45 min) than the commercially available technologies (24 h).

Improved microvessel repair: laser welding with an anti-thrombotic solder.

BACKGROUND AND OBJECTIVES: Concentrated protein solutions can be used as thermally polymerized solders in laser welding. Solders supplemented with biologically active chemicals may provide in situ drug delivery for localized therapeutics. These studies characterize a serum albumin (SA) solder containing heparin, designed to reduce microvascular thrombosis rates. STUDY DESIGN/MATERIALS AND METHODS: Samples of heparin added to 30% SA to obtain heparin-to-albumin molar ratios (HAMR) of 4:1 and 2:1 were thermally polymerized, and heparin release into saline was measured. Using a rat thrombosis model, patency was determined for suture, and 0 U/ml (control), 2.5 U/ml, 50 U/ml heparin solder repairs. RESULTS: Heparin release was five times higher for 4:1 than 2:1 HAMR solder acutely, but was equivalent after 2 days. Animal patency rates were: 50% suture, 0% control, 50% low heparin, 66% high heparin (P < 0.05 vs. control). CONCLUSIONS: Solders incorporating heparin should provide in situ anti-thrombotic therapy reducing the risk of microvascular thromboses.