At pH 6.4, the mucoadhesive properties of chitosan and the three conjugates (TM-chitosan, TM-GN-chitosan and TM-GN-HT-chitosan) were decreased slightly compared to that at pH 4.0, but were still higher than that at pH 1.2. This is because at pH values above 6, the amino groups of chitosan became largely deprotonated and so uncharged ( NH2), as were the+N(CH3)3 group sof the TM-chitosan too. At the same time, the OH and SH groups of the conjugates were able to form hydrogen and covalent bonds, respectively, with the native mucin. In addition, the side chain of the HT ( CH2groups) could interact with the sidechain of native mucin (–CH3groups) to increase the van der Waals’interactions
In conclusion, electrostatic and hydrophobic interactions and hydrogen and covalent bonding all had an effect on the mucoadhesive properties of chitosan, TM-chitosan, TM-GN-chitosan and TM-GN-HT-chitosan at all pH values, but especially at a neutral to alkaline pH
4. Conclusion
A TM-GN-HT-chitosan polymer was successfully synthesized by covalent conjugation of HT on to the primary amine groups ( NH2)of TM-GN-chitosan. This modified polymer had an enhanced watesolubility, especially at a neutral to basic pH, and exhibited higher mucoadhesive properties than that of chitosan or TM-GN-chitosan over the tested pH range (pH 1.2–6.4). Increasing the number of cationic groups, hydroxyl groups and thiol groups increased the water solubility and mucoadhesiveness of the TM-GN-HT-chitosan
Acknowledgements
The authors gratefully acknowledge funding from the Asia Research Center and the Ratchadaphiseksomphot Endowment Fund of Chulalongkorn University to N.M. (RES560530064-FW).The authors also thank Dr. Robert Butcher of the PCU, Faculty ofScience, Chulalongkorn University for constructive comments andEnglish corrections
At pH 6.4, the mucoadhesive properties of chitosan and the three conjugates (TM-chitosan, TM-GN-chitosan and TM-GN-HT-chitosan) were decreased slightly compared to that at pH 4.0, but were still higher than that at pH 1.2. This is because at pH values above 6, the amino groups of chitosan became largely deprotonated and so uncharged ( NH2), as were the+N(CH3)3 group sof the TM-chitosan too. At the same time, the OH and SH groups of the conjugates were able to form hydrogen and covalent bonds, respectively, with the native mucin. In addition, the side chain of the HT ( CH2groups) could interact with the sidechain of native mucin (–CH3groups) to increase the van der Waals’interactions In conclusion, electrostatic and hydrophobic interactions and hydrogen and covalent bonding all had an effect on the mucoadhesive properties of chitosan, TM-chitosan, TM-GN-chitosan and TM-GN-HT-chitosan at all pH values, but especially at a neutral to alkaline pH 4. Conclusion A TM-GN-HT-chitosan polymer was successfully synthesized by covalent conjugation of HT on to the primary amine groups ( NH2)of TM-GN-chitosan. This modified polymer had an enhanced watesolubility, especially at a neutral to basic pH, and exhibited higher mucoadhesive properties than that of chitosan or TM-GN-chitosan over the tested pH range (pH 1.2–6.4). Increasing the number of cationic groups, hydroxyl groups and thiol groups increased the water solubility and mucoadhesiveness of the TM-GN-HT-chitosan Acknowledgements The authors gratefully acknowledge funding from the Asia Research Center and the Ratchadaphiseksomphot Endowment Fund of Chulalongkorn University to N.M. (RES560530064-FW).The authors also thank Dr. Robert Butcher of the PCU, Faculty ofScience, Chulalongkorn University for constructive comments andEnglish corrections
การแปล กรุณารอสักครู่..