Scope of solid lipid nanoparticles per se as all-purpose moisturising sunscreens

Abstract

Sun blocking effect is defined as the ability to protect the skin against ultraviolet-induced damage, indicated in terms of sun protection factor (SPF). This protection can be physical or chemical. Chemical sun protecting agents can permeate the skin leading to toxic side effects. Solid lipid nanoparticles (SLNs), also known as lipid carriers have been widely investigated across the world and have evolved as promising nano-sized drug carriers. In this study, different placebo SLN formulations demonstrate sun protection. Five different SLN formulations (F1–F5) with varying lipid content were developed using three industry amenable techniques viz. high speed stirring (HSH), high pressure homogenisation (HPH) and microemulsification method (MEM). A correlation between morphology (HR TEM), particle size-polydispersity index (DLS), sun protection factor (SPF) and occlusive effect (OE) were established. Results indicated promising SPF (6.0–24.0) and hydrating effects (OE 6.0–71.0) of spherical, mono disperse lipidic nanoparticles with lipid content of ≥4%. SLNs were found to offer hydration effects comparable to Vaseline® petroleum jelly (OE 71.0 and 82.0, respectively). Hence, SLNs per se can be regarded as: (i) safe alternative to current toxic chemical sunscreen agents, or (ii) carriers for latter, employed at low concentration to provide similar effects, and (iii) as suitable moisturisers.