Biocompatible sodium alginate fibers by aqueous processing and physical crosslinking

Sodium alginate (SA) hybrid fibers have been robustly fabricated by electrospinning of aqueous mixtures containing as high as 60% SA in the presence of polyvinyl alcohol (PVA). Solution viscosities of SA, PVA and their mixtures showed fiber spinning to be strongly influenced by the balance between SA-PVA and PVA-PVA intermolecular polar interaction and SA-SA repulsion. Low viscosity SAl (50 mPas at 1%) enabled higher SA loadings without significantly increasing mixture viscosities, producing more cylindrical fibers. All aqueous mixtures containing 33.3-60% SAl (5.68-7.15% total SAl-PVA) had viscosities ranging from 530 to 3600 mPas and could be electrospun continuously for at least 48 h. The SA-PVA hybrid fibers had diameters ranging from ca. 140 to 350 nm and were rendered stable in water via simultaneous ionic-crosslinking SA and crystallization of PVA (5% CaCl2 in 75% EtOH for 30 min). This aqueous electrospinning and physical crosslinking approach is a green and highly efficient alternative to create alginate hybrid fibers that are biologically compatible and ingestible for potential biomedical, food and other applications.