Antimicrobial cellulosic hydrogel from olive oil industrial residue Sawsan Dacrory a, ⁎, Hussein Abou-Yousef a , Ragab E. Abouzeid a , Samir Kamel a , Mohamed S. Abdel-aziz b , Mohamed El-badry c a Cellulose and Paper Department, National Research Centre, 33 El Bohouth st. (former El tahrir st.), P.O. 12622, Dokki, Giza, Egypt b Microbial Chemistry Department, National Research Centre, 33 El Bohouth st. (former El tahrir st.), P.O. 12622, Dokki, Giza, Egypt c Chemistry Department, Ain Shams University, Abassia, Cairo, Egypt abstract article info Article history: Received 24 April 2018 Received in revised form 21 May 2018 Accepted 24 May 2018 Available online 25 May 2018 The cellulose-based antimicrobial hydrogel was prepared from seed and husk cellulosic fibers of olive industry residues by load silver nanoparticles (AgNPs) onto grafted acrylamide monomer (Am) cellulosic fibers. The grafting approach was the free radical mechanism by utilizing ceric ammonium nitrate (CAN) as initiator in aque- ous medium and N,N methylene bisacrylamide (MBAm) as a cross linker. The effect of different grafting condi- tions on the properties of produced hydrogels has been studied by determining the grafting parameters, i.e. concentration of Am, MBAm, grafting time and temperature to optimize grafting yield (G %), grafting efficiency (GE %), and swelling %. Characterizations of the obtained hydrogels were performed through monitoring swelling behavior, FTIR spectroscopy, SEM, and EDX. AgNPs were grown into the prepared hydrogel. Hydrogel/AgNPs were characterized by FT-IR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The hydrogel loaded AgNPs exhibit high efficient antimicrobial activity against Staphylococcus aureus, Pseudomo- nas aeruginosa, and Candida albicans. © 2018 Elsevier B.V. All rights reserved. Keywords: Acrylamide Olive stone residue Grafting Silver nanoparticles Antimicrobial hydrogel 1. Introduction Olive stone was produced as a lignocellulosic byproduct during olive oil extraction and its major constituents are hemicelluloses, cellulose and lignin in addition to proteins, fat, phenols, free sugars as well as po- lios. Olive stone consists of two main portions husk and seed residues, from which cellulosic fibers can be produced by different delignification processes. The olive fruit is consisting of skin and pulp. Both of skin and pulp represent the husk of olive fruit. And the stone, that contains the seed [1]. Utilization of olive stone was limited for production of energy by combustion or activated carbon. In addition to furfural production, and plastic filler as well as its uses as animal nutrition and resin manu- facture [2]. Cellulose, the major component of this lignocellulosic mate- rial, is an organic polysaccharide consisting of D-glucose units linked to each other by β (1 → 4) glucosidic linkage [3]. Each D-glucose possess hydroxyl groups (-OH) at positions C2, C3 and C6 which typically reacted as secondary and primary alcohols, respectively. Many modifi- cation processes have been reported in the literature to improve the properties of the native cellulose. Grafting is one of the most imported approached utilized for cellulose modification. Grafting of cellulose is a striking study because its products could possess any number of required properties [4][5]. Grafting has been performed by several methods, but free radicals are the most convenient methods as they generate radicals on the cellulosic backbone before grafting [6–8]. It can be performed with different initiator systems which are widely used to synthesize graft copolymers and they include ammonium per- sulfate, potassium persulfate, benzoyl peroxide, azobisisobutyronitrile and ceric ammonium nitrate [9–11]. To the best of our knowledge, no work has been directed towards grafting of acrylamide using ceric am- monium nitrate as initiator and in the presence of MBAm to form hydro- gel onto olive oil by-products and then loaded with AgNPs by impregnation of grafted cellulose in AgNO 3 solution followed by using trisodium citrate solution. Antimicrobial materials have a great signifi- cance in many areas including medical applications, water purification systems, textiles and food packaging. AgNPs have been known to have strong antimicrobial activity. The loading of AgNPs was widespread in many scientific research due to it have much attention to control infec- tions [12] and also have antibacterial properties than bulk silver as a re- sult of high surface area which leading to incorporating more nanoparticles inside the bacteria and stop its action [13]. In addition, AgNPs were nontoxic to human cells [14]. The current study focused on using olive stone for production of antimi- crobial hydrogel by loading AgNPs onto grafted cellulosic fibers which ex- tracted from seed or husk portions of olive stone. Optimization of the grafting condition was achieved by attempt to investigate different grafting conditions. The study aim to make characterization of the prepared International Journal of Biological Macromolecules 117 (2018) 179–188 ⁎ Corresponding author. E-mail address: sd.ali@nrc.sci.eg (S. Dacrory). https://doi.org/10.1016/j.ijbiomac.2018.05.179 0141-8130/© 2018 Elsevier B.V. All rights reserved. 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