Preparation and structural characterization of surface modified microporous bacterial cellulose scaffolds: A potential material for skin regeneration applications in vitro and in vivo Shaukat Khan a,b , Mazhar Ul-Islam a,c , Muhammad Ikram d , Salman Ul Islam e , Muhammad Wajid Ullah a,f , Muhammad Israr a , Jae Hyun Jang a , Sik Yoon d , Joong Kon Park a, ⁎ a Department of Chemical Engineering, Kyungpook National University, Daegu, Republic of Korea b Materials Science Institute, PCFM Lab and GDHPRC Lab, School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, PR China c Department of Chemical Engineering, College of Engineering, Dhofar University, Salalah, Oman d Department of Anatomy, Pusan National University School of Medicine, Yangsan, Gyeongsangnam-do, Republic of Korea e School of Life Sciences, College of Natural Sciences, Kyungpook National University, Daegu, Republic of Korea f Department of Biomedical Engineering, College of Life Sciences and Technology, Huazhong University of Science and Technology, Wuhan 430074, PR China abstract article info Article history: Received 8 March 2018 Received in revised form 6 June 2018 Accepted 8 June 2018 Available online xxxx This study reports the fabrication of porogen-induced, surface-modified, 3-dimensionally microporous regener- ated bacterial cellulose (rBC)/gelatin (3DMP rBC/G) scaffolds for skin regeneration applications. Round shaped gelatin microspheres (GMS), fabricated using a water-in-oil emulsion (WOE) method, were utilized as the porogen. The dissolution of GMS from the solution casted BC scaffolds led to surface-modified microporous rBC. The scaffolds were characterized using field emission scanning electron microscopy (FE-SEM) and elemental analysis. FE-SEM analysis confirmed the regular microporosity of the 3DMP rBC/G scaffolds, while elemental analysis confirmed the successful surface modification of cellulose with gelatin. In vitro tests showed good adhe- sion and proliferation of human keratinocytes (HaCaT) on the 3DMP rBC/G scaffolds during 7 days of incubation. Confocal microscopy showed penetration of HaCaT cells into the scaffolds, up to 300 μm in depth. In vivo wound healing and skin regeneration experiments, in experimental mice, showed complete skin regeneration within 2 weeks. The wound closure efficacy of the 3DMP rBC/G scaffolds was much higher (93%) than that of the control (47%) and pure BC-treated (63%) wounds. These results indicated that our 3DMP rBC/G scaffolds represent future candidate materials for skin regeneration applications. © 2017 Elsevier B.V. All rights reserved. Keywords: Bacterial cellulose Porogen Scaffold Microspheres Biocompatibility Skin regeneration 1. Introduction Currently, skin wounds, such as burns, scalds, and chronic wounds, are major concerns for dermatologists and orthopedic surgeons. Artifi- cial skin and dressings are required to treat acute wounds. However, the current commercial wound dressings fail to meet the properties of an ideal dressing material for skin regeneration [1]. The two major re- quirements for an ideal dressing are its ability to absorb wound exu- dates during the healing process, and non-adherence to the wound, leading to easy removal after complete healing. Cotton gauze is the most famous dressing material, which is permeable and absorbent; however, it adheres to the wound, leading to secondary injuries during dressing change and removal after complete healing, which prolongs the healing process. To overcome such limitations, scientists attempted to develop new dressing materials utilizing biopolymers and new cell and molecular biology methods that would lead to efficient skin repair. Among the biopolymers, cellulose is the most abundant material easily biodegraded by cellulase enzyme bearing animals [1, 2]. Although bacterial cellulose (BC) has the same chemical structure as plant cellu- lose, it shows unique characteristics [3]. BC has very high water absorp- tion and retention properties, high permeability, and good mechanical properties [4, 5]. BC has been explored for a wide range of applications in medical fields, such as wound dressing material, artificial skin, artifi- cial vessels and valves, bone regeneration, and tissue engineering scaf- folds [6]. Recent studies have shown that BC-based wound dressings are exceptional healing materials because of their high absorption of ex- udates and non-adherent properties. BC has demonstrated efficient healing of different wounds when applied as a dressing material or arti- ficial skin [7]. However, the absence of 3-dimensional (3D) microporos- ity and limited biocompatibility has restricted its application as a scaffold for skin regeneration in vivo. Therefore, introduction of con- trolled 3D microporosity and enhanced biocompatibility through International Journal of Biological Macromolecules 117 (2018) 1200–1210 ⁎ Corresponding author. E-mail address: parkjk@knu.ac.kr (J.K. Park). https://doi.org/10.1016/j.ijbiomac.2018.06.044 0141-8130/© 2017 Elsevier B.V. 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