Gelatin electrospun (e-spun) fiber mats containing nisin were produced by electrostatic spinning of gelatin-nisin in 70% (vol/vol) acetic acid aqueous solutions. Varying nisin loading concentration (0 to 3% [wt/wt]) did not affect the fiber average diameter, whereas increasing gelatin concentration from 20 to 24% (wt/vol) caused an increase in the average diameter. All nisin-loaded gelatin e-spun fiber mats demonstrated inhibition against Lactobacillus plantarum TISTR 850. However, all fiber mats were fragile and easily dissolved in water. Cross-linking by saturated glutaraldehyde vapor at 37°C for 5 min was done to strengthen the mat. Tensile strength, Young's modulus, and elongation of the cross-linked gelatin-nisin e-spun fiber mats varied in the range of 2.6 to 20.3 MPa, 163 to 966 MPa, and 1.7 to 5.9%, respectively. Cross-linking did not affect the mat's inhibition activity against L. plantarum TISTR 850. Nisin retention in cross-linked antimicrobial gelatin e-spun fiber mats was in the range of 1.0 to 1.22%. Increasing temperature caused an increase in nisin release, but increasing water activity did not cause a significant difference in nisin release over 50 h. After storage at 25°C for 5 months, the antimicrobial gelatin e-spun fiber mat still showed inhibition against L. plantarum TISTR 850. The mats also inhibited the growth of Staphylococcus aureus and Listeria monocytogenes but not Salmonella Typhimurium.
Novel biocompatible electrospun gelatin fiber mats with antibiotic drug delivery properties