Aqueous electrospinning of wheat gluten fibers with thiolated additives

The molecular weight distribution (MWD), rheology and electrospinning of a series of wheat gluten (WG) mixtures with poly(vinyl alcohol) (PVA), dithiothreitol (DTT), and thiolated poly(vinyl alcohol) (TPVA) in water/1-propanol (1/1) were investigated by size-exclusion chromatography, steady-shear viscosity measurements and scanning electron microscopy. Thiolated additives reduce disulfide bonds between protein subunits and thus increase WG solubility. Accordingly, Newtonian behavior is observed for pure components and PVA/WG, and shear-thinning for DTT/WG and TPVA/WG. Concentration, viscosity and additive type affect WG electrospinnability. At higher concentrations, PVA/WG fibers are thicker than WG ones, whereas DTT/WG and TPVA/WG fibers are thinner and beadless. While at low concentrations both DTT/WG and TPVA/WG generate poor fibers, lowering TPVA thiolation level results in better fibers, unobtainable with DTT. Thus, although using only the lower end of the WG MWD, reasonably good fibers can nonetheless be obtained with an inexpensive aqueous system and very low additive amounts.