International Journal of Pharmaceutics 391 (2010) 267–273 Contents lists available at ScienceDirect International Journal of Pharmaceutics journal homepage: www.elsevier.com/locate/ijpharm Pharmaceutical Nanotechnology High loading fragrance encapsulation based on a polymer-blend: Preparation and release behavior Aurapan Sansukcharearnpon a,c , Supason Wanichwecharungruang b,∗ , Natchanun Leepipatpaiboon b , Teerakiat Kerdcharoen d , Sunatda Arayachukeat a a Program of Petrochemistry and Polymer Science, Chulalongkorn University, Bangkok 10330, Thailand b Department of Chemistry, Faculty of Science, Chulalongkorn University, Payatai Road, Patumwan, Bangkok 10330, Thailand c National Center of Petroleum, Petrochemicals and Advanced Materials, Chulalongkorn University, Bangkok 10330, Thailand d Department of Physics, Center of NANO, Faculty of Science, Mahidol University, Bangkok 10400, Thailand article info Article history: Received 24 November 2009 Received in revised form 6 January 2010 Accepted 10 February 2010 Available online 17 February 2010 Keywords: Nanoparticles Fragrance Encapsulation Controlled release TGA Essential oil abstract The six fragrances, camphor, citronellal, eucalyptol, limonene, menthol and 4-tert-butylcyclohexyl acetate, which represent different chemical functionalities, were encapsulated with a polymer-blend of ethylcellulose (EC), hydroxypropyl methylcellulose (HPMC) and poly(vinyl alcohol) (PV(OH)) using solvent displacement (ethanol displaced by water). The process gave ≥40% fragrance loading capacity with ≥80% encapsulation efficiency at the fragrance to polymer weight ratio of 1:1 and at initial polymer concentrations of 2000–16,000 ppm and the obtained fragrance-encapsulated spheres showed hydrody- namic diameters of less than 450 nm. The release profile of the encapsulated fragrances, evaluated by both thermal gravimetric and electronic nose techniques, indicated different release characteristics amongst the six encapsulated fragrances. Limonene showed the fastest release with essentially no retention by the nanoparticles, while eucalyptol and menthol showed the slowest release. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Components in essential oils are secondary metabolites with unique odors. They are used worldwide not only in folk medicine, spa, cosmetics and toiletries, but also in many scented house- hold and occupational products. Scientific studies on the biological actions of these essential oils have already started to accumulate (Fukumoto et al., 2006; Moretti et al., 2002; Morita et al., 2003). These unique odorous molecules are being synthesized or isolated from natural sources and used as fragrance components in various industries. However, many of these fragrance molecules are unsta- ble due to their reactive functionalities, such as aldehyde, ketone and terpenes. Degradation not only causes changes in their sensory characteristics, but also, in many cases, creates allergenic products (Karlberg et al., 1992; Matura et al., 2005, 2006). It has been known that control of the volatilization rate and degradation is the heart of prolonging the sensory characteristics of fragrance materials. One way of doing so is encapsulation, which provides both stabilization and a controlled release of the entrapped materials. Other benefits of encapsulation include ease of handling (e.g. a stable solid encap- sulated product instead of an unstable volatile liquid), improved ∗ Corresponding author. Tel.: +66 2 218 7634; fax: +66 2 254 1309. E-mail address: psupason@chula.ac.th (S. Wanichwecharungruang). safety (e.g. reduced flammability) and an increased applicability to various products (e.g. water dispersible essential oil-encapsulated spheres can be easily applied in water based formulations). How- ever, the fragrance release properties are the key issue in selecting a particular encapsulation technology. The existing fragrance encapsulation technologies includes dou- ble emulsion preparation (Edris and Bergnståhl, 2001), molecular inclusion into a host, such as cyclodextrin (Wang and Chen, 2005), incorporation into solid lipid nanoparticles using appropriate lipids and surfactants (Lai et al., 2006), coacervation with various carbo- hydrates with and without the use of crosslinking agents (Soper et al., 2000; Chang and Dobashi, 2003), interfacial polymerization based on various polymers, such as polyurethane-urea (PUU) and phenol–formaldehydes (Ouall and Lahoussine, 2006; Scarfato et al., 2007; Hwang et al., 2006a,b; Rodrigues et al., 2008) and in situ polymerization, such as the synthesis of fragrance-encapsulated mesoporous silica spheres (Wang et al., 2008). Amongst these, interfacial polymerization and complex coacervation are the two most popular choices. Partial solubility in water of many essential oils’ components usually causes instability in the microencapsulation by interfa- cial reactions because of the change in the hydrolytic stability of the particle during polymerization reaction. Moreover, side reac- tions between the monomers with several reactive functionalities of the essential oil’s components can lead to some alteration of the 0378-5173/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.ijpharm.2010.02.020