# Synthesis of Star Nanoparticles and Their Applications for Bioactive Compound Encapsulation  
[PERSON]  
1 Department of Chemical and Environmental Engineering, University of Oviedo, Julian Claveria 8, 33006 Oviedo, Spain; [EMAIL_ADDRESS] (D.M. ); [EMAIL_ADDRESS] (G.G.) [PERSON]  
1 Department of Chemical and Environmental Engineering, University of Oviedo, Julian Claveria 8, 33006 Oviedo, Spain; [EMAIL_ADDRESS] (D.M. ); [EMAIL_ADDRESS] (G.G.) [PERSON]  
2 Instituto Universitario de Biotecnologia de Asturias, University of Oviedo, 33006 Oviedo, Spain; [EMAIL_ADDRESS]  
[PERSON]  
4 Department of Food Technology, Engineering, and Nutrition, Lund University, P.O. Box 124, 5E 221 00 Lund, Sweden; ali.marefatiffood.lth.se (A.M.); [EMAIL_ADDRESS] (M.R.) [PERSON]  
4 Correspondence: [EMAIL_ADDRESS]; Tel. : +34-985-103029; Fax: +34-985-10343  
the possibilities offered by new materials, whose physical and chemical properties are on the border between those exhibited by atoms and those of matter on a larger scale. These materials are known as nanoparticles [2; 3]. Today the nanoparticles field is experiencing a great expansion in scientific research thanks to its potential for application in sectors such as medicine, cosmetics, and food, among other areas. Encapsulation is a process in which small particles or droplets are surrounded by a coating or embedded in a homogeneous or heterogeneous matrix. The adsorption of bioactive compounds on the carrier is accomplished through weak chemical interactions such as hydrogen bonding and Van der Waals forces. The choice of bioactive compound loading method depends on the size of the molecule to be encapsulated and its hydrophilic/lipophilic character [4]. At the same time, the loading method used for bioactive compounds also affects the release. The efficacy and the effect of these loading methods on the release characteristics of the loaded bioactive compounds have been previously studied to some extent [5]. Starch-based carriers are widely used in the encapsulation and control release of bioactive compounds for applications in food and pharmaceutical formulations due to their high biocompatibility and their small size which offers a high surface/volume ratio and high surface/weight ratio when hollow SNPs are synthesized [6; 7; 8]. However, there is little research on the delivery of bioactive compounds using starch-based nanoparticles [9; 10]. Moreover, even the majority of the review articles focus on the methods frequently used for fabrication of the SNPs, while reports on the encapsulation methods on SNPs are scarce. For the broader application of starch-based nanoparticles as carrier for bioactive compounds, it is important to investigate the loading and release properties of starch nanoparticles using model bioactive compounds. In this review, different techniques for the synthesis of SNPs are described and the different size ranges obtained in each case are reviewed. Some recent novel developed techniques, such as ultrasound and high-pressure homogenization, are included. The SNPs sizes obtained were dependant on the selected synthesis method as well as the type of the starch used as the natural raw material (e.g., corn starch, banana starch, potato starch, etc.) and also the possible modifications (e.g., chemical modification, amylose/amylopectin content modification, etc.). Different types of SNPs synthesized using different parameters are reviewed. Hollow particles or coated particles prepared by novel methods, such as the sacrificial template method, are also included. Also, a revision of the advantages and disadvantages that polymeric NPs present compared to NPs synthesized with other type of materials was made (Table 1). Moreover, special attention has been paid to the encapsulation of bioactive compounds as one of the main bioapplications of SNPs. Two main different types of encapsulation methods were described depending on whether the bioactive compounds were encapsulated (direct or indirect).