Fabrication and characterization of Pluronic modified poly(hydroxybutyrate) fibers for potential wound dressing applications Arijit Bhattacharjee 1 , Krishan Kumar 1 , Aditya Arora, Dhirendra S. Katti ⁎ Department of Biological Sciences and Bioengineering, Indian Institute of Technology — Kanpur, Kanpur 208016, Uttar Pradesh, India abstract article info Article history: Received 6 December 2015 Received in revised form 15 February 2016 Accepted 26 February 2016 Available online 27 February 2016 Electrospun poly(hydroxybutyrate) (PHB) fiber meshes have shown some success in wound dressing applica- tions, however, their use is limited by their high hydrophobicity and brittle nature. In this study we investigated the effect of hydrophilization of electrospun PHB fibers by blending with Pluronic F-108 (PF) for use as a wound dressing material. Blending of PHB with different concentrations of PF (0.5%PF-PHB and 1.0% PF-PHB) before electrospinning led to a significant increase in the water wettability and swelling properties of fibers as compared to pristine PHB fibers. Further, it was observed that though the tensile moduli of PF blended PHB fibers were rel- atively lower as compared to PHB fibers, they show higher resistance to failure measured in terms of strain to fail- ure and energy to failure. Moreover, PF blending significantly improved the in vitro blood clotting rate on PHB fibers when compared to control PHB fibers. Furthermore, the fabricated fiber systems were found to be cytocompatible and supported adhesion of fibroblasts in vitro. Finally, it was demonstrated that the PF blended fiber systems were suitable for the encapsulation of an antibiotic (doxycycline) to render them with antibacterial properties. Taken together, this study demonstrates that PF blending can be used to significantly improve prop- erties of PHB fibers for wound dressing applications. © 2016 Elsevier B.V. All rights reserved. Keywords: Poly(hydroxybutyrate) Pluronic F-108 Surface modification Wound dressing Wettability Doxycycline 1. Introduction Acute and chronic dermal wounds due to surgery, burns and chronic ulcers that demand clinical care afflict N 80 million people worldwide [1]. Since improper management of such wounds can lead to delayed wound healing and infection, wound dressings have become an indispensable component of effective wound management. An ideal wound dressing should protect the wound from physical damage/me- chanical tear [2], provide adequate gaseous and nutrient exchange [2, 3], absorb excess wound exudates and prevent chances of microbial in- fection thereby enhancing the rate of wound healing [3,4]. Further, the wound dressing material should be non-toxic and facilitate cell adhe- sion, migration and proliferation in order to promote tissue repair and regeneration [4,5]. Recently, electrospun micro-/nano-fibers have been widely ex- plored in wound dressing applications as they possess high surface area to volume ratio, high porosity, interconnected pores and suitable mechanical properties required for a wound dressing [4,6–11]. More- over, the ability of electrospun fibers to act as a delivery vehicle for a va- riety of bioactive molecules such as pharmaceutical agents (drugs), and growth factors to the site of injury makes them even more suitable for wound dressing applications [12]. Electrospun fibers from a variety of materials both natural and synthetic have been explored in wound healing applications [13]. Poly(hydroxybutyrate) (PHB) is one of the polymers of natural origin whose fibers have been explored as a wound dressing material as well as for fabrication of scaffolds for vari- ous tissue engineering applications due to its biocompatibility, process- ability and degradability [14,15]. However, the highly hydrophobic and brittle nature of PHB limits its application as a wound dressing material. This is crucial as previous reports suggest that hydrophilic materials are more suitable as wound dressings as they can absorb excess wound ex- udates and yet maintain a moist environment in the wound thereby mediating faster healing response [16]. Hence, we hypothesized that suitable surface modification of PHB fibers so as to make it hydrophilic may improve the performance of PHB fibers in wound dressing applications. Previous reports from our group have demonstrated that when a hy- drophobic polymer like poly(lactide-co-glycolide) (PLGA) is blended with an amphiphilic block co-polymer like Pluronic® F-108 (PF) before electrospinning/spraying, it leads to preferential accumulation of the block co-polymer on the surface of the fibers/particles [17,18]. This led to a significant improvement in the water wettability, swelling proper- ties and mechanical properties of the electrospun fibers [17,19,20]. Apart from improvement in the material properties of fibers, PF blend- ing significantly improved protein adsorption as well as its downstream events such as cell adhesion and spreading on the electrospun fibers [19,21]. Materials Science and Engineering C 63 (2016) 266–273 ⁎ Corresponding author. E-mail address: dsk@iitk.ac.in (D.S. Katti). 1 These authors contributed equally to this work. http://dx.doi.org/10.1016/j.msec.2016.02.074 0928-4931/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Materials Science and Engineering C journal homepage: www.elsevier.com/locate/msec