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First-Principles Based Approaches to Nano-Mechanical and Biomimetic Characterization of Polymer-Based Hydrogel Networks for Cartilage Scaffold-Supported Therapies

Jaramillo-Botero, Andres and Blanco, Mario and Li, Youyong and McGuinness, Garrett and Goddard, William A., III (2010) First-Principles Based Approaches to Nano-Mechanical and Biomimetic Characterization of Polymer-Based Hydrogel Networks for Cartilage Scaffold-Supported Therapies. Journal of Computational and Theoretical Nanoscience, 7 (7). pp. 1238-1256. ISSN 1546-1955.

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Atomistic-level molecular dynamics (MD) is used to investigate the thermodynamical and mechanical properties of candidate polymer-based hydrogel networks for tissue scaffold-support therapies that serve a predominantly biomechanical function, in particular articular cartilage. The MD uses force field parameters based on quantum mechanical calculations (including atomic charges and torsional potential energy curves). We provide first principles estimates of the entropic and enthalpic contributions to elastic response, cohesive energies, viscosities, and stress-strain characteristics for relevant single and double network hydrogel compositions of poly(acrylamide)-PAAm and poly(2-acrylamido-2-methylpropanesulfonic acid)-PAMPS, aimed at the functional bio-engineering of artificial tissue with high dynamic load requirements (>10's of MPa even at >90 wt-% water contents). Our results indicate the existence of covalent cross-linking mechanisms taking place during the synthesis of interpenetrating double network hydrogels at critical crosslink concentrations and as a function of starter monomer concentrations and degree of polymerization. Furthermore, percolation thresholds estimated from single chain statistics of acrylamide polymers are consistent with experimentally measured gel points and help explain the precipitous loss of the high fracture energy in double network hydrogels at low crosslink densities; favoring this mechanism, over others presented in the literature (e.g., entanglement, hydrogen bonding), as the origin of enhanced toughness for interpenetrating double network hydrogels. These findings are useful for steering experimental efforts towards systematic optimization of the bio-mimetic response of polymer-based scaffolds for tissue engineering.

Item Type:Article
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URLURL TypeDescription
Jaramillo-Botero, Andres0000-0003-2844-0756
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2010 American Scientific Publishers. The work performed by Jaramillo-Botero, Blanco, Li and Goddard is based upon work supported by the National Science Foundation under Grant No. 0727870, and by the Teragrid Project under TG-DAC grant No. DMR080054T. Large-scale parallel MD calculations on >25K atom systems where performed using an inhouse Dreiding/ReaxFF modified version of LAMMPS77 running on the Pittsburg Supercomputer Center's Cray XT3 system. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the National Science Foundation or any of its partners. McGuinness spent the academic year 200812009 on sabbatical leave from Dublin City University at the Materials and Process Simulation Center, California Institute of Technology.
Funding AgencyGrant Number
Teragrid ProjectDMR080054T
Subject Keywords:Molecular Dynamics; Single and Double Hydrogel Networks; Cartilage Scaffold-Supported Cell Therapy; Mechanical and Thermodynamic Properties of Hydrogels
Issue or Number:7
Record Number:CaltechAUTHORS:20100713-122828560
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:19031
Deposited By: Jason Perez
Deposited On:19 Jul 2010 17:13
Last Modified:03 Oct 2019 01:51

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