Thiolation is another method to increase the mucoadhesion effect -especially the permeability of the nanoparticles -of chitosan nanoparticles. Thiolation is a process in which thiols -R-SH -are introduced into the chitosan by directly reacting any chemical compounds with the thiol group with chitosan. This technique has been pioneered by Bernkop-Schnürch et. al to enhance the mucoadhesion of polymers for pharmaceutical and biomedical applications. The derivatives of the thiolation include cysteine, thioglycolic acid (TGA), 2-iminothiolane or 4-thiobutylamidine, N-acetyl cysteine, isopropyl-S-acetylthioacetimidate and glutathione. According to the research conducted by Ways et.al, chitosan tablets showed superior cohesion over the chitosan tablets which could be due to the formation of intra/intermolecular disulfide bonds as a result of the oxidation of the thiol groups in thiolated chitosan. This improved cohesion is desirable for the mucoadhesion and the design of controlled-release dosage forms.