Influence of SLN Matrix on "in vitro" and "in vivo" nanoparticle performances

This study focuses on the production of solid lipid nanoparticles (SLN) loaded with the hydrophilic carbonyl quencher N-acetylcarnosine (NAC) in order to develop topical formulations useful in several skin diseases and in the photoageing prevention and treatment. The addition of amphiphilic substances into lipid matrix, such as phosphatidylcholine (PC), polyglyceryl-3-diisostearate and sorbitan monooleate, was evaluated. The influence of additives on "in vitro" SLN performances was investigated by Differential Scanning Calorimetry, size and zeta potential, active content analyses, release and occlusion tests. Preliminary "in vivo" investigations of cutaneous tolerability and short-term effect of SLN application were also carried out using non-invasive skin bioengineering techniques. Results obtained from this work allowed to conclude that the incorporation of these additives, in concentration of 15% with respect to lipid mass, strongly affects colloidal systems physical properties leading to a very different in in vitro and in vivo performances. In particular, encapsulation efficiency can be very good reaching the 65.75% by addition of PC into lipid matrix. In vivo evaluation evidenced good cutaneous tolerability for all batches produced. The presence of PC can significantly modify the short-term effect of SLN application on the skin with respect to both vehicle alone and unmodified SLN.