545 Introduction Diabetes has a worldwide enhancement and incidence, thus new methods to overcome conventional insulin therapy (subcutaneous injection) have been exploited to be delivered using diferent nanocarriers. [1–3] Like most proteins and peptides, insulin has a low bioavailability due to its hydrophilic character, relatively high molecular weight and deactivation by enzymatic and proteolytic degradation. [1,4,5] Nanocarriers are efective alternatives to other dosage forms existing on the market and also to overcome fail- ures in conventional insulin therapy. [6,7] Among these systems, solid lipid nanoparticles (SLNs): [8–15] (i) allow a controlled release reducing the frequency of administra- tion (often painful and uncomfortable for patients); (ii) protect the drug from degradation in vivo and in vitro; (iii) anticipate a high tolerance due to the use of physi- ological lipids; (iv) allow industrial scale production; and (v) the drug delivery may occur directly on the target site and therefore greatly increases its bioavailability. Due to these characteristics, insulin can be administered orally through this system and overcome the low bioavailability (1–2%) associated with gastrointestinal tract that destroys the physiological activity of this bioactive. [13,14,16–18] Using nanoparticles as drug delivery systems, there is a need to rapidly and cost-efectively assess the toxicity of nanoparticles. he costs for testing nanomaterials are estimated to be above $1.1 billion. [19] Nanoparticles have properties diferent from their bulk counterparts due to the increased surface area afecting the ability to pass through cell membranes and cross biological barriers, thus there is a compelling need to rapidly assess nanomaterial toxicity. [20] RESEARCH ARTICLE A novel lipid nanocarrier for insulin delivery: production, characterization and toxicity testing J. F. Fangueiro 1 , E. Gonzalez-Mira 2,3 , P. Martins-Lopes 4 , M. A. Egea 2,3 , M. L. Garcia 2,3 , S. B. Souto 5 , and E. B. Souto 1,4 1 Faculty of Health Sciences, Fernando Pessoa University, Rua Carlos da Maia, Porto, Portugal, 2 Department of Physical Chemistry, Faculty of Pharmacy, University of Barcelona, Barcelona, Spain, 3 Institute of Nanoscience and Nanotechnology, University of Barcelona, Barcelona, Spain, 4 Institute of Biotechnology and Bioengineering, Centre of Genomics and Biotechnology, Vila Real, Portugal, and 5 Department of Endocrinology, Hospital de São João, University of Porto Medical School, Alameda Prof. Dr. Hernâni Monteiro, Porto, Portugal Abstract 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 diferential scanning calorimetry (DSC) and toxicity analysis by Drosophila melanogaster testing. Insulin-SLNs were composed of Softisan®100 1.25% wt, Lutrol®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®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. Keywords: Solid lipid nanoparticles, insulin, Softisan ® 100, nanocarriers, Drosophila melanogaster, nanotoxicology Address for Correspondence: Eliana B. Souto, Faculty of Health Sciences of Fernando Pessoa University, Rua Carlos da Maia, 296, Oice S.1, P-4200-150 Porto, Portugal. Tel: +351 22 507 4630 (Ext. 3056). Fax: +351 22 550 4637. E-mail: eliana@ufp.edu.pt (Received 14 April 2011; revised 03 May 2011; accepted 07 May 2011) Pharmaceutical Development and Technology, 2013; 18(3): 545–549 © 2013 Informa Healthcare USA, Inc. ISSN 1083-7450 print/ISSN 1097-9867 online DOI: 10.3109/10837450.2011.591804 Pharmaceutical Development and Technology Downloaded from informahealthcare.com by Universidade Fernando Pessoa on 11/06/13 For personal use only.