International Journal of Biological Macromolecules 87 (2016) 48–54 Contents lists available at ScienceDirect International Journal of Biological Macromolecules journal homepage: www.elsevier.com/locate/ijbiomac Preparation and characterization of acetylated starch nanoparticles as drug carrier: Ciprofloxacin as a model Seyed Heydar Mahmoudi Najafi ∗ , Maryam Baghaie, Alireza Ashori Department of Chemical Technologies, Iranian Research Organization for Science and Technology (IROST), P.O. Box 33535111, Tehran, Iran a r t i c l e i n f o Article history: Received 17 December 2015 Received in revised form 2 February 2016 Accepted 11 February 2016 Available online 15 February 2016 Keywords: Acetylated corn starch Ciprofloxacin Nanoprecipitation Encapsulation Drug carrier a b s t r a c t The objective of this study was to characterize in-vitro the potential of acetylated corn starch (ACS) particles as a matrix for the delivery of ciprofloxacin (CFx). ACS was successfully synthesized and opti- mized by the reaction of native corn starch using acetic anhydride and acetic acid with low and high degrees of substitution (DS). The nanoprecipitation method was applied for the formation of the ACS- based nanoparticles, by the dropwise addition of water to acetone solution of ACS under stirring. The effects of acetylation and nanoprecipitation on the morphology and granular structure of ACS samples were examined by the FT-IR, XRD, DSL and SEM techniques. The efficiency of CFx loading was also evalu- ated via encapsulation efficiency (EE) in ACS nanoparticles. The average degree of acetyl substitution per glucose residue of corn starch was 0.33, 2.00, and 2.66. The nanoparticles size of the ACS and ACS-loaded with CFx were measured and analyzed relative to the solvent:non-solvent ratio. Based on the results, ACS nanoparticles with DS of 2.00 and water:acetone of 3:1 had 312 nm diameter. Increasing DS in starch acetate led to increase in the EE from 67.7 to 89.1% and with increasing ratio of water/acetone from 1:1 to 3:1, the EE raised from 48.5 to 89.1%. X-ray diffraction indicated that A-type pattern of native starch was completely transformed into the V-type pattern of acetylated starch. The scanning electron microscopy showed that the different sizes of pores formed on the acetylated starch granules were utterly converted into the uniform-sized spherical nanoparticles after the nanoprecipitation. © 2016 Elsevier B.V. All rights reserved. 1. Introduction Starch is a natural, renewable, biodegradable, biocompatible, and cost-effective polysaccharide, which has been widely used in various applications [1,2]. It is the second most abundant biomass material in nature after cellulose [3]. Starch is a carbohydrate stor- age product found in all plants containing chlorophyll, such as corn, potato, rice, tapioca, wheat, sorghum and barley [4]. The amount and type of associated material vary depending on which part of plant the starch comes from. One major difference is due to the source, such as from cereal seeds (corn, wheat, etc.), from tubers (potato) or from roots (tapioca). Starch is white, insolu- ble in cold water because of the polymerized structure, and has hydrogen bonding between adjacent chains. Starch is composed of linear molecules called amylose and branched molecules called amylopectin [5]. Their structures, physical and chemical properties are compared in Table 1 [6]. The starch industry extracts and refines ∗ Corresponding author. E-mail address: mahmoudi@irost.ir (S.H. Mahmoudi Najafi). starches by wet grinding, sieving, and drying processes. It is either used as extracted from the plant and is called “native starch”, or it undergoes one or more chemical modifications to reach specific properties and is called “modified starch” [7]. Recently, polymer nanoparticles have attracted significant interest in chemistry, pharmaceutics and biomaterial science for biomedical application and controlled release [8,9]. Among the known carbohydrate polymers, starch has been used in the fields of drug delivery and biocatalysts, because of its advantages, such as improving drug solubility and stability, decreasing drug toxi- city and side effects, and excellent biocompatibility and storage stability [10,11]. However, native starch is not suitable for con- trolled drug release due to its physical and chemical properties [12]. To further meet and improve its properties and extend the application of starch in the food and biomedical areas, all kinds of modifications including blending and chemical modification, such as oxidation, crosslinking and hydroxypropylation, have been con- sidered by many researchers [13–15]. Chemical modification is the most useful tool to customize the overall performance of native starch. Acetylated starch as a starch derivative can be produced by esterification of native starch with acetic anhydride (AA). Through http://dx.doi.org/10.1016/j.ijbiomac.2016.02.030 0141-8130/© 2016 Elsevier B.V. All rights reserved.