Contents lists available at ScienceDirect European Polymer Journal journal homepage: www.elsevier.com/locate/europolj Effects of gamma irradiation and periodate oxidation on the structure of dextrin assessed by mass spectrometry Isabel Pereira a, ⁎ , Joana Simões b , Dmitry V. Evtyugin c , Sophie Rouif d , Manuel A. Coimbra b , M. Rosário M. Domingues b , Miguel Gama a a CEB – Centre of Biological Engineering, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal b QOPNA, Department of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal c CICECO, Department of Chemistry, University of Aveiro, Campus de Santiago, 3810-193 Aveiro, Portugal d IONISOS, Parc Dombes Côtière Activités, Route de Balan, F-01120 Dagneux, France ARTICLE INFO Keywords: Dextrin Periodate oxidation Gamma irradiation Electrospray ionization mass spectrometry MALDI-MS Biomedical application ABSTRACT Sterilization of biomaterials by gamma irradiation should not change its structure, since this may affect also its bioactivity. In this work, dextrin and periodate-oxidized dextrin (ODEX), both irradiated and non-irradiated, were hydrolysed by α-amylase and the obtained oligosaccharides were fractionated by ligand-exchange/size exclusion chromatography and analyzed by matrix-assisted laser desorption/ionization (MALDI-MS) and elec- trospray ionization (ESI-MS n ) mass spectrometry. This allowed the identification of structures formed during partial periodate oxidation, which displayed aldehyde groups in different positions of dextrin backbone, ac- cording to the type of residue which was oxidized. Importantly, gamma irradiation did not structurally change either dextrin or ODEX, showing that it can be used as suitable terminal sterilization method of these materials for biomedical applications. To our best knowledge, this is the first report using MS-based techniques to evaluate the effects of partial periodate oxidation and of gamma irradiation on polysaccharides and, in particular, on dextrin and its oxidized form. 1. Introduction Dextrins are low-molecular-weight carbohydrates produced by partial hydrolysis of glycogen or starch obtained under acidic and/or enzymatic conditions [1]. They are composed by a linear (α1→4)-D- glucose residues backbone, branched with (α1→4,6)-linked-D-glucose residues containing terminal or (α1→4)-D-glucose oligomers. Some dextrins also present (α1→6)-D-glucose residues in small percentage [2,3]. Dextrin is a low cost, broadly available raw material widely used in many industrial applications, such as adhesives in the manufacture of gummed tapes, textiles and paper, as moisturiser in cosmetics and ac- cepted in food applications as a generally-recognized-as-safe (GRAS) ingredient [1,3]. Regarding biomedical applications, dextrin is still re- latively unexplored, being clinically used as a peritoneal dialysis solu- tion that can also perform as a drug delivery solution [4–6], and as wound dressing agent [7]. During last decade, due to its properties, which include the solubility in both water and DMSO, availability in medical grade, and availability of hydroxyl groups, dextrin has been explored for the design and fabrication of (nano)hydrogels suitable for controlled release applications, tissue engineering scaffolds, excipient in tablets, bioadhesives or drug conjugates. Such applications have been extensively reviewed by Gonçalves et al. [1] and by Das and Pal [8]. Dextrin was used by our research group to develop a fully resorb- able and injectable hydrogel. Dextrin was firstly oxidized (ODEX) with sodium periodate (NaIO 4 ) and then cross-linked with adipic acid di- hydrazide, a non-toxic cross-linking molecule. The cross-linked ODEX is an in situ gelling hydrogel, able to incorporate nanogels, cells, biomo- lecules, and granular ceramics for bone regeneration applications [2,9,10]. Periodate oxidation (“glycol cleavage” oxidation) is a simple and effective method for introduction reactive groups in polysaccharide backbones. It is a catalysis-free aqueous reaction, where periodate ion (IO 4 - ) attacks vicinal diols to cleave the carbon–carbon bond, leading to the formation of two aldehyde groups [11]. Initially, this method was routinely used in the characterization and elucidation of the poly- saccharide structure through complete oxidation [11]. In later years, low and mild periodate oxidations have been used to functionalize https://doi.org/10.1016/j.eurpolymj.2018.04.011 Received 27 February 2018; Received in revised form 4 April 2018; Accepted 10 April 2018 ⁎ Corresponding author. E-mail addresses: isabelsofia.isport@gmail.com (I. Pereira), joana.simoes@ua.pt (J. Simões), dmitrye@ua.pt (D.V. Evtyugin), sophie.rouif@ionisos.fr (S. Rouif), mac@ua.pt (M.A. Coimbra), mrd@ua.pt (M.R.M. Domingues), fmgama@deb.uminho.pt (M. Gama). European Polymer Journal 103 (2018) 158–169 Available online 11 April 2018 0014-3057/ © 2018 Elsevier Ltd. All rights reserved. T