Nanoencapsulation, biocompatibility and antibiofilm properties of chitosan/nisin Z spheres

To study antibiofilm formation properties and biocompatibility of nisin Z for oral applications by encapsulating it in a highly muco-adhesive chitosan nanosphere and testing its effects against a multispecies biofilm and in vitro wound healing assay. Nisin Z was encapsulated in chitosan. Encapsulation parameters were evaluated using dynamic light scattering and visualised with microscopy. The effects on biofilm growth were tested using a Calgary biofilm device against a five species biofilm model. The effects on human gingival fibroblast (HGF) growth and migration were examined using an Idibi (500 nm gap) migration assay and the percentage of gap closure measured using ImageJ. 20,000 IU/ml (0.525 mg/ml production concentration) nisin Z in a 1:40 ratio of TPP:chitosan produced optimal nanospheres with a low polydispersity index of 0.498 and average size of 264.8 nm. The freeze-dried nanospheres have a dose-dependent effect on biofilm formation, significantly reducing biofilm attachment compared to the positive control. No colonies were observed for chitosan/nisin Z nanospheres at > 6.25 mg/ml. HGFs in the control and 1000 IU nisin Z (unencapsulated) groups showed the most gap closure. The treatment group containing 50 mg/ml chitosan/nisin Z nanospheres showed gap closure comparable to the control. Chitosan/nisin Z nanospheres were produced with antibiofilm activity with > 6.25 mg/ml nanospheres, while up to 50 mg/ml had no significant effect on HGF gap closure in vitro. Thus, nanoencapsulated nisin Z has potential as a therapeutic agent for the treatment of periodontitis.