title: Rheological Study and Molecular Dynamics Simulation of Biopolymer Blend Thermogels of Tunable Strength.
abstract: The temperature-induced gelation of chitosan/glycerophosphate (Chs/GP) systems through physical interactions has shown great potential for various biomedical applications. In the present work, hydroxyethyl cellulose (HEC) was added to the thermosensitive Chs/GP solution to improve the mechanical strength and gel properties of the incipient Chs/HEC/GP gel in comparison with the Chs/GP hydrogel at body temperature. The physical features of the macromolecular complexes formed by the synergistic interaction between chitosan and hydroxyethyl cellulose in the presence of β-glycerophosphate disodium salt solution have been studied essentially from a rheological point of view. The temperature and time sweep rheological characterizations of the thermogelling systems revealed that the sol-gel transition temperature of the Chs/HEC/GP blends is equal to 37 °C at neutral pH; with increasing HEC content in the solutions, more compact networks with considerably improved gel strength are formed without influencing the gelation time. The formed hydrogel matrix has enough mechanical integrity and adequate strength for using it as injectable in situ forming matrices for biomedical applications. The classical Winter-Chambon (W-C) and Fredrickson-Larson (F-L) theories were applied to determine the gel point. In view of the obtained results, it is shown that the F-L theory can be employed as a robust and less tedious method than the W-C approach to precisely determine the gel point in these systems. At the end, molecular simulation studies were conducted by using ab initio quantum mechanics (QM) calculations carried out on Chs and HEC models, and molecular dynamics (MD) simulations of solvated Chs/HEC blend systems showed the binding behavior of Chs/HEC polymers. Analyses of interaction energy, radial distribution function, and hydrogen bonding from simulation studies strongly supported the experimental results; they all disclosed that hydrogen-bond formation between Chs moieties with regard to HEC chains plays an important role for the stabilization of the complexes.
authors: Department of Developmental Sciences, Marquette University School of Dentistry , Milwaukee, Wisconsin, United States.|Department of Chemistry, University of Oslo , Oslo, Norway.|Department of Polymer Engineering and Color Technology, Amirkabir University of Technology , Tehran, Iran.
authors: Erfan
authors: E
authors: Dashtimoghadam
authors: Department of Engineering and Technology, Golestan University , Aliabad Katool, Iran.
authors: Ghasem
authors: G
authors: Bahlakeh
authors: Faculty of Engineering and Technology, University of Mazandaran , Babolsar, Iran.
authors: Hamed
authors: H
authors: Salimi-Kenari
authors: Laboratoire de Microsystemes (LMIS4), Institute of Microengineering, Institute of Bioengineering, École Polytechnique Fédérale de Lausanne (EPFL) , Lausanne, Switzerland.|Parker H. Petit Institute for Bioengineering and Bioscience and G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology , Atlanta, Georgia, United States.
authors: Mohammad Mahdi
authors: MM
authors: Hasani-Sadrabadi
authors: Department of Polymer Engineering and Color Technology, Amirkabir University of Technology , Tehran, Iran.
authors: Hamid
authors: H
authors: Mirzadeh
authors: Department of Chemistry, University of Oslo , Oslo, Norway.
authors: Bo
authors: B
authors: Nyström
mesh_terms: D002482:Cellulose / Q000737:chemistry*; D048271:Chitosan / Q000737:chemistry*; D005994:Glycerophosphates / Q000737:chemistry*; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry; D046911:Macromolecular Substances; D055595:Mechanical Phenomena; D056004:Molecular Dynamics Simulation; D011108:Polymers / Q000737:chemistry*; D011789:Quantum Theory; D012212:Rheology; D013696:Temperature
chemical_list: D005994:Glycerophosphates; D046911:Macromolecular Substances; D011108:Polymers; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D002482:Cellulose; D048271:Chitosan