A novel lipid nanocarrier for insulin delivery: production, characterization and toxicity testing

A novel nanocarrier based on solid lipid nanoparticles (SLNs) was developed for insulin delivery using a novel double emulsion method. Physical stability of particles was assessed by size analysis using dynamic light scattering (DLS), matrix crystallinity by differential scanning calorimetry (DSC) and toxicity analysis by Drosophila melanogaster testing. Insulin-SLNs were composed of Softisan (R) 100 1.25% wt, Lutrol (R) F68 1% wt, soybean lecithin 0.125% wt, and loaded with 0.73-0.58 mg/mL peptide. Placebo-SLNs (insulin-free) also contained 0.025% wt Tween (R) 80. Mean particle sizes of placebo-SLN and insulin-SLN were 958 +/- 9.5 and 978 +/- 8.3 nm, respectively. The polydispersity index (PI) was 0.28 +/- 0.018 and 0.29 +/- 0.013, respectively. Polarized light microscopy analysis depicted no aggregation of developed particles. DSC analysis allowed characterizing SLN with 43-51% matrix crystallinity. Using Drosophila melanogaster test, no toxicity was reported for SLN and for the bulk lipid. This study shows that SLNs are promising and helpful to overcome conventional insulin therapy, in particular for their lack of toxicity for oral delivery.