Non-covalent crosslinkers for electrospun chitosan fibers

► GP, TA and TPP were used to non-covalently crosslink electrospun chitosan. ► OS and activated OS crosslinking produces unbranched fibers. ► TS and activated TS crosslinking yield branched/web electrospun chitosan fibers. ► Activation of TS chitosan-TPP and TS chitosan-TA mats are insoluble in water for 72h. ► TS chitosan-TA electrospun mats are insoluble in 1M AA for 72h. Electrospun chitosan fibers have numerous potential in biomedical, food, and pharmaceutical applications. However, the mats formed are often not chemically stable in a wide range of pHs unless crosslinked. Here, we report on the use of glycerol phosphate (GP), tripolyphosphate (TPP) and tannic acid (TA) as a new set of non-covalent crosslinkers for electrospun chitosan fibers. Crosslinking with or without heat or base activation were performed either prior to (one-step or activated one-step) or after (two-step or activated two-step) electrospinning with either GP or TA. TPP crosslinking was performed in two-step and activated two-step. FESEM, FTIR and UV–vis transmittance at 600nm were used to determine fiber surface morphology, chemical interactions and solubility in 1M AA (pH 3), water (∼pH 6) and 1M NaOH (pH 13), respectively. Crosslinking of chitosan with GP and TA yields fibers with a mean diameter range of 145–334nm and 143–5554nm, respectively. TPP crosslinking produced branched fibers with mean diameters of 117–462nm range. Two-step chitosan-TA did not dissolve in 1M AA even after 72h while all chitosan-TPP, activated two-step chitosan-TA and two-step heat activated chitosan-GP fibers survived in water after 72h.