Carbohydrate Polymers 88 (2012) 1378–1386 Contents lists available at SciVerse ScienceDirect Carbohydrate Polymers j ourna l ho me pag e: www.elsevier.com/locate/carbpol Preparation of tailor-made starch-based aerogel microspheres by the emulsion-gelation method C.A. García-González a,∗ , J.J. Uy a , M. Alnaief b , I. Smirnova a,∗ a Institute of Thermal Separation Processes, Hamburg University of Technology, Eißendorferstraße 38, D-21073 Hamburg, Germany b School of Applied Medical Sciences, German Jordanian University, P.O. Box 35247, 11180 Amman, Jordan a r t i c l e i n f o Article history: Received 24 November 2011 Received in revised form 31 January 2012 Accepted 13 February 2012 Available online 22 February 2012 Keywords: Starch Aerogel Supercritical drying Emulsion-gelation Chemical carrier matrix a b s t r a c t The inherent biocompatibility and biodegradability of starch, a natural polysaccharide-based product, allows its use in the form of microspheres as a chemical carrier for life science applications. However, current methods of preparation of starch microspheres utilize chemical crosslinkers and drying methods (air drying, freeze drying) that leads to problems of degradability of the matrix and low specific surface areas and chemical loading capacities. In this work, corn starch aerogel microspheres, a special class of nanoporous materials, were prepared by the combination of an emulsion-gelation method and supercrit- ical drying without the use of chemical crosslinkers. Effects of gelation temperature (368, 393 and 413 K), oil-to-aqueous starch solution ratio (1:1, 2:1, 3:1) and surfactant content (3, 6 and 10% (w/w)) on the textural and morphological properties of the aerogel material were studied. The obtained starch aero- gels were characterized using nitrogen adsorption–desorption measurements, helium pycnometry, CHN elemental analyses, thermogravimetry and scanning electron microscopy. Spherical starch aerogel micro- spheres with tailor-made specific surface areas (34–120 m 2 g -1 range) and particle sizes (215–1226 m diameter range) were obtained. Aerogel textural properties were mainly influenced by the gelation tem- perature used, whereas the particle morphology depended on the three processing parameters studied. High specific chemical loading capacity (1.1 × 10 -3 g m -2 ) of the aerogel microspheres was obtained using ketoprofen as a model compound. © 2012 Elsevier Ltd. All rights reserved. 1. Introduction Microparticles made from natural products (e.g., polysaccha- rides), in the form of microspheres or microcapsules, have been proposed as advantageous delivery carriers for the controlled release of active compounds, agrochemicals and food bioactives for life sciences applications (Elfstrand, Eliasson, & Wahlgren, 2009; Li et al., 2009; Malafaya, Stappers, & Reis, 2006; Wing, Carr, Trimnell, & Doane, 1991). These carriers can effectively protect the entrapped substance against environmental degradation (e.g., pH, temperature, humidity, enzymes, microorganisms) (Dumitriu, 2005; Müller, Mäder, & Gohla, 2000; Smith & Williams, 2006). The microparticulate carrier can be designed for use in various routes of administration as well as for the controlled and targeted release of active chemicals. This customized performance of the carrier leads to an enhanced efficacy of delivery, reduced toxicity, and improved customer acceptance. ∗ Corresponding authors. Tel.: +49 40 42878 3642; fax: +49 40 42878 4072. E-mail addresses: carlos.garcia@tuhh.de (C.A. García-González), irina.smirnova@tuhh.de (I. Smirnova). Starch is an abundant, edible, low toxic and low-cost polysac- charide found in the leaves, seeds and tubers of many vegetables (e.g., potato, corn, pea, wheat, tapioca) in the form of granules. The good biodegradability and stability of starch and its versatility in processing (Doane, 1992; Duarte, Mano, & Reis, 2009; Dumitriu, 2005; Wing et al., 1991) makes it a promising delivery carrier for drug, biomedical, agriculture and food applications. The sub- stance to be entrapped can be physically (adsorption) or chemically attached to the starch matrix (Miao, Li, Deng, Wang, & Liu, 2010; Yang, Wei, Sun, & Wan, 2010). For pharmaceutical purposes, starch microspheres have been reported to be used via the nasal, par- enteral, oral administration routes for magnetic resonance imaging, chemotherapy for liver cancer or drug delivery among others (Fang et al., 2008; Ishida et al., 2008; Kim et al., 2003; Mundargi, Shelke, Rokhade, Patil, & Aminabhavi, 2008). Starch microspheres are also proposed for tissue engineering applications by simulta- neous injection with the scaffold at the site of regeneration and for encapsulation of living cells (Malafaya et al., 2006). In agriculture, starch microspheres meet the market demand for easy-to-handle carriers allowing the effective slow-release of agrochemicals, thus reducing the amount of chemical to be applied, the frequency of application and the environmental impact (Glenn et al., 2010). For the food industry, starch is used in edible films to coat food and also 0144-8617/$ – see front matter © 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.carbpol.2012.02.023