Nanobiotechnology for health-care

The degradation kinetics of the post-neutralized electrospun chitosan nanofibrous membranes with different dichloromethane/trifluoroacetic ratio
Korniienko V.V.1, HusakYe.V.1, Holubnycha V.M.1, Yanovska A.O.1, Pogorielov M.V.1

1Sumy State University, 2, Rymsky-Korsakov Str., Sumy 40007, Ukraine 
E-mail: vicorn77g@gmail.com

Introduction. Chitosan solutions are highly viscous and complicated for electrospinning due to presence of free amino groups that makes it a positively charged polyelectrolyte under acidic conditions. Increasing the acid concentration in chitosan solution can influence on the chitosan structure that lead to pure mechanical parameters of membranes and make them quickly degradable in an aqueous environment [1].
Objectives. Optimization of chitosan solution for electrospinning in different dichloromethane/trifluoroacetic (TFA/DCM) ratio and assessment of swelling capacity (SC) and weight loss (WL) of electrospun membranes after alkali treatment. 
Methods. 3.5% (w/v) chitosan solutions were prepared by dissolving in TFA/DCM (7:3 and 9:1, v/v). After electrospinning membranes were neutralized in 1M Na2CO3 solution (aqueous). Difference between the wet swollen samples and the dried samples measurements (%) was taken for the determination of SC and WL after submersion in phosphate buffer saline (PBS; pH=7.4) at various time intervals (20 and 60 min for SC and 1 day and 3 days for WL). 
Results. Swelling properties of chitosan membranes prepared in 9:1 TFA/DCM ratio were in 2 and 1.5 times higher than of the nanofibers created in 7:3 cosolvents system after 20 and 60 min submersion in PBS. Weight loss was significantly higher for sample prepared in 9:1 TFA/DCM ratio (p≤0.05) at all time points of experiment.
Conclusion. The nanofibrous membranes fabricated from chitosan solution in 9:1 TFA/DCM ratio possessed greater level of SC and WL that can be explained by the removing bigger amount of TFA and consequently higher weight reduction within neutralization and immersion into PBS during the experiment.
Acknowledgements. This research was funded by EU-H2020-MSCA-RISE, grant no 777926 NanoSurf.
References
1.	Sencadas V. еt al. Determination of The parameters affecting electrospun chitosan ﬁber size distribution and morphology // Carbohydrate Polymers. – 2012. – 87. – P. 1295–1301.