Electrospinning of biopolymer solutions into fibers enables the fabrication of materials with desirable mechanical and biophysical properties. Sodium alginate, known for its biocompatibility and biodegradability, has recently emerged as a promising material for bacterial therapy, in which live bacteria embedded in an alginate fiber mesh are used to treat infections. In order to be electrospun, alginate can be combined with a high molecular weight carrier polymer that enhances the shear and extensional viscosity of the solution. These rheological properties influence the ability of the solution to form fibers—a property also known as spinnability—by controlling the dynamics of filament formation, thinning, and breakup, which ultimately dictate the morphology of the resulting fibers. Here we investigate the shear and extensional rheology of solutions composed of sodium alginate, a high MW poly(ethylene oxide) (PEO) carrier polymer, and commercial probiotics. We find that the concentrations and molecular weights of the alginate and the carrier polymer significantly influence the solution rheology, as well as the distribution of fiber diameters after electrospinning. By linking the composition and rheology of biopolymer solutions to the morphology of the electrospun fibers, we seek to enable the rational design and optimization of fiber-based, probiotic-loaded materials for bacterial therapy.
