Stable Nanoemulsion System Development Enabling the Topical Delivery of Synechococcus-Derived Peptides

Abstract

Marine microalgae including Synechococcus sp. VDW offer the potential to serve as a source of bioactive peptides offering valuable antioxidant and antimelanogenic qualities for use in the pharmaceutical and cosmetics industries. At present, however, the use of such peptides is challenging due to their poor physicochemical stability. This research therefore sought to achieve the production and characterization of a stable nanoemulsion system based upon the use of synthetic Synechococcus-derived peptides through the process of high-pressure homogenization (HPH). Preparation of the nanoemulsions involved the use of Tween-80 and caprylic/capric triglyceride at a pressure of 7,500 psi to perform homogenization for varying durations of 15, 30 and 45 min. Using the optimized formulation with 0.1% w/w peptide for a time of 45 min resulted in 122.16 nm droplets while the zeta potential was −80.09 mV and the PDI (polydispersity index) value was 0.13. Colloidal stability could be considered high, while physical stability under thermal cycling, centrifugation and freeze-thaw cycles was very good, with no phase separation. For all testing intervals, the viscosity and refractive index were stable. It can thus be argues that the HPH approach is suitable to produce peptide-loaded nanoemulsions offering good stability and useful physicochemical characteristics. The developed nanoemulsion system has been optimized to offer potential for applications involving the transdermal delivery of marine peptides in the cosmeceutical sector and for a range of dermal therapies. HIGHLIGHTS Developed a stable peptide-loaded nanoemulsion using high-pressure homogenization (HPH) at 7,500 psi for 45 min. Achieved small, uniform droplet size (122.16 nm), high zeta potential (−80.09 mV) and low PDI (0.13), indicating strong colloidal stability. Nanoemulsion exhibited excellent physical stability under centrifugation, freeze–thaw and heating–cooling cycles. Increased peptide concentration led to decreased pH and viscosity, optimizing flow and emulsification properties. Potential application in transdermal delivery systems for cosmeceuticals and dermatological formulations. GRAPHICAL ABSTRACT