BACKGROUND: Some of the problems with electrospun zein fiber are that it has very low tenacities in the dry and wet states and that mats of the fiber become films when immersed in water. The fibers are therefore unusable for various applications despite their good biocompatibility and biodegradability. This research was conducted to overcome these problems by electrospinning novel fibers containing various concentrations of zein, citric acid (CA) and sodium hypophosphite monohydrate (SHP) and by crosslinking the zein with CA and with SHP serving as a catalyst. RESULTS: The CA-crosslinked electrospun zein fiber has as much as 10-fold greater wet tenacity and 15-fold greater dry tenacity than regular electrospun zein fiber. The average diameter of these fibers is 451 nm, which is the smallest diameter ever reported for zein-based electrospun fiber. A mat of this fiber retains its fibrous structure when immersed in water, and the fiber retains about 70% of its tenacity after 16 days at 50 degrees C and 90% relative humidity. CONCLUSION: The high dry and wet tenacities, good water stability and small diameter of the novel CA-crosslinked electrospun zein fiber make it attractive for biomedical and other applications that expose zein to water or that require high surface area. (C) 2008 Society of Chemical Industry