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 mPa s 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 mPa s 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.