A barrier membrane comprising electrospun chitosan nanofibers, wherein the electrospun chitosan nanofibers are reversibly surface acylated at —OH groups by exposing the electrospun chitosan nanofibers to an acylating catalyst selected from the group consisting of pyridine, 4-dimethylamino-pyridine (DMAP), triethylamine, diisopropylethylamine (DIPEA), lutidine, aluminum chloride, aluminum trifluoride, triphenylphosphine, tributylphosphine, and combinations thereof and an acylating agent selected from the group consisting of a butyric anhydride, acyl chloride, symmetric or mixed acid anhydride, vinyl ester, cyanomethyl ester, S-phenyl thioester, piperidino ester, pyrid-3-yl ester, 4-nitrophenyl ester, 2,4,6-trichlorophenyl ester, 2,3,4,5,6- pentachlorophenyl ester, 2,3,4,5,6-pentafluorophenyl ester, phtalimido ester, succinimido ester, 4-oxo-3,4-dihydrobenzotriazin-3-yl ester, benzotriazolyl ester, and combinations thereof, wherein, during surface acylation, —NH2 groups of the chitosan nanofibers are not acylated.