Enhanced photoprotection for photo-labile compounds using double-layer coated corn oil-nanoemulsions with chitosan and lignosulfonate.

With the aim to establish a novel nanocarrier system with relatively high payload and high photoprotection capacity for photo-labile active compounds, in this work, deltamethrin (photo-labile compound) was encapsulated into corn oil-nanoemulsions (NE) by a hot high pressure homogenization technique followed by coating with chitosan as the first coating layer (CH-NE) and lignosulfonate as the second coating layer to form a double-layer coated NE (L-CH-NE). The optimal conditions for preparation of NE, chitosan coating and lignosulfonate coating were investigated. The results indicate that polymer coating and the number of coating layers significantly affected the release profile and photoprotection capacity of nanocarriers. In particular, after coating, the release rate became slower and photoprotection capacity became higher. Moreover, in the case of L-CH-NE after 24h of UV exposure in direct photolysis and 2.5h of UV exposure in indirect photolysis, the non-degraded amount of deltamethrin was approximately 4.5 times and 2.1 times, respectively, higher than that of the free-from deltamethrin. In the future, this novel nanocarrier system will show great potential and be widely applied to many fields related to protection of photo-labile compounds against photo-degradation.