Abstract Skin, hair and mucosal surfaces are useful targets for the delivery of active compounds, botanicals and, importantly, drugs. Encapsulation provides an invaluable tool to the cosmetic and/or pharmaceutical formulator, providing great flexibility in the choice of delivery mechanisms and excipients that can be used. Dispersions of solid lipid nanoparticles (SLNs) were prepared using biodegradable materials generally regarded as safe by a melt-emulsify-chill (MEC) method. Among the materials encapsulated in SLNs were hydrophobic active pharmaceutical ingredients, antiviral and fungicidal compounds, organic UV absorbers and fluorescent dyes. The loading, adhesion and intracellular localization of the SLNs were studied as a function of surface charge.
The MEC process can easily, and cheaply, produce a range of solid lipid nanoparticles (SLNs) – “smart colloids” – that offer flexibility in formulation, increased efficacy and decreased formulation complexity. The method is general and can be applied to many water- or oil- soluble cosmetic and pharmaceutical actives. Multiple actives can be co-encapsulated. The process is cost-effective, reproducible, robust and scalable. The bulk physical characteristics and surface chemical properties can be varied to allow systems to be custom designed to fit specific applications; use can be made of this in the targeting of encapsulated actives, botanicals and therapeutics to skin and hair.
The non-specific nature of cellular uptake would suggest that SLNs produced via the MEC process are suitable candidates for delivering surface attached actives into cells. The strong attachment and demonstrated entry into antigen presenting cells of the immune system illustrates the potential that these natural wax nanoparticles might have in vaccine formulations.