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Title:   Author  item
                                            SOUSA, ANA - The University Of Portoitem
                                            SOUZA, H.K.S. - The University Of Portoitem
                                            Uknalis, Josephitem
                                            LIU, S.C. - Chung Shan Medical Universityitem
                                            GONCALVES, M.P. - The University Of Portoitem
                                            Liu, Linshu
  Submitted to: Carbohydrate Polymers
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 8/10/2014
                                    Publication  Date: 1/22/2015
                                    Publication URL: http://handle.nal.usda.gov/10113/61660Citation: Sousa, A., Souza, H., Uknalis, J., Liu, S., Goncalves, M., Liu, L.S. 2015. Electrospinning of agar/PVA aqueous solutions and its relation with rheological properties. Carbohydrate Polymers. 115:348-355. DOI: 10.1016/j.carbpol.2014.08.074.Interpretive Summary: Agar, a polymer extracted from a type of red seaweed, is valued for its gelling properties. Agar is biocompatible and biodegradable and preliminary research has demonstrated its applicability in preparing wound dressings. While fibers based on agar have a large potential for applications in the pharmaceutical industries and in the manufacture of biomedical materials, they can only be made by a method that uses harsh chemicals. A method that uses water to make the fibers is more desirable. In this study, very small (submicron and nanosize) agar-based fibers that can only be seen using a microscope were made by first mixing aqueous solutions of agar with an environmentally benign polymer know as polyvinyl alcohol (PVA) to serve as a support for the agar. The solutions were then processed using the electrospinning technique which works by applying a high voltage to the solution, causing the water to evaporate leaving behind the submicron agar/PVA fibers. The agar/PVA blends were easily electrospun if the amount of agar was less than that of the PVA and resulted in good fibers. The results from this study open a new window of opportunities for agar-based biomaterials.
                                Technical Abstract: In this work, we report the successful fabrication of agar-based nanofibers by an electrospinning technique using water as the solvent media. A tubeless spinneret was attached inside the electrospinning chamber, operated at 50 deg C, to avoid agar gelation. Pure agar solution 1% (w/w) showed inadequate spinnability regardless of electrospinning conditions. The addition of a co-blending polymer such as PVA (10 % (w/w) starting solution) improved solution viscoelasticity and hence, solution spinnability. Agar/PVA solutions were prepared with different mass ratios (100/0, 50/50, 40/60, 30/70, 20/80 and 0/100) and electrospun at various sets conditions. Best nanofibers were obtained with 30/70 and 20/80 agar/PVA blends while samples with higher agar contents (50/50 and 40/60 agar/PVA) were harder to process and led to discontinuous fibrous mats. This first set of encouraging results opens a new window of opportunities for agar-based biomaterials in the form of nanofibers.


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