title: Improving agar electrospinnability with choline-based deep eutectic solvents.
abstract: Very recently our group has produced novel agar-based fibers by an electrospinning technique using water as solvent and polyvinyl alcohol (PVA) as co-blending polymer. Here, we tested the deep eutectic solvent (DES), (2-hydroxyethyl)trimethylammonium chloride/urea prepared at 1:2 molar ratio, as an alternative solvent medium for agar electrospinning. The electrospun materials were collected with an ethanol bath adapted to a previous electrospinning set-up. One weight percent agar-in-DES showed improved viscoelasticity and hence, spinnability, when compared to 1 wt% agar-in-water and pure agar nanofibers were successfully electrospun if working above the temperature of sol-gel transition (∼80 °C). By changing the solvent medium we decreased the PVA concentration (5 wt% starting solution) and successfully produced composite fibers with high agar contents (50/50 agar/PVA). Best composite fibers were formed with the 50/50 and 30/70 agar/PVA solutions. These fibers were mechanically resistant, showed tailorable surface roughness and diverse size distributions, with most of the diameters falling in the sub-micron range. Both nano and micro forms of agar fibers (used separately or combined) may have potential for the design of new and highly functional agar-based materials.
authors.affiliation: REQUIMTE/LAQV, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal; Dairy Functional Food Research Unit, United States Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
authors.forename: Ana M M
authors.initials: AM
authors.lastname: Sousa
authors.affiliation: REQUIMTE/LAQV, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Hiléia K S
authors.initials: HK
authors.lastname: Souza
authors.affiliation: Dairy Functional Food Research Unit, United States Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Uknalis
authors.affiliation: Dairy Functional Food Research Unit, United States Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA; School of Health Diet and Industry Management, Chung Shan Medical University; Hospital Department of Nutrition, Chung Shan Medical University. 110, Sec. 1, Jian-Guo North Rd., Taichung, 402, Taiwan, ROC.
authors.forename: Shih-Chuan
authors.initials: SC
authors.lastname: Liu
authors.affiliation: REQUIMTE/LAQV, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
authors.forename: Maria P
authors.initials: MP
authors.lastname: Gonçalves
authors.affiliation: Dairy Functional Food Research Unit, United States Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA. Electronic address: LinShu.liu@ars.usda.gov.
authors.forename: LinShu
authors.initials: L
authors.lastname: Liu
mesh_terms: D000362:Agar / Q000737:chemistry*; D002794:Choline / Q000737:chemistry*; D004548:Elasticity; D055664:Electrochemical Techniques; D057139:Nanofibers / Q000737:chemistry*; D011142:Polyvinyl Alcohol / Q000737:chemistry; D000644:Quaternary Ammonium Compounds / Q000737:chemistry; D012996:Solutions; D012997:Solvents / Q000737:chemistry; D055682:Viscoelastic Substances / Q000737:chemistry*; D014783:Viscosity
chemical_list: C528098:(2-hydroxyethyl) trimethylammonium hydroxide; D000644:Quaternary Ammonium Compounds; D012996:Solutions; D012997:Solvents; D055682:Viscoelastic Substances; D000362:Agar; D011142:Polyvinyl Alcohol; D002794:Choline
keywords: Agar; Deep eutectic solvents; Electrospinning; Microfibers; Nanofibers; PVA