Effects of Molecular Weight and Concentration of Poly(Acrylic Acid) on Biomimetic Mineralization of Collagen

Yipin Qi, Zhou Ye, Alex Fok, Brian N. Holmes, Montserrat Espanol, Maria Pau Ginebra, Conrado Aparicio

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Inspired by nature, poly(acrylic acid) (PAA) and other polyelectrolytes have been used as noncollagenous proteins (NCPs) surrogates for biomimetic intrafibrillar mineralization of collagen fibrils and, thus, to model the ultrastructure of bone, to study the mechanism of bone mineralization, and more scarcely to fabricate scaffolds for hard tissue engineering. The objective of this study was to systematically investigate the effect of the molecular weight (MW) and the concentration of PAA on the rate and pattern of biomineralization of collagen matrices. Densified type I collagen films were mineralized in supersaturated PAA-stabilized amorphous calcium-phosphate (PAA-ACP) solutions containing increasing MW (2 kDa, 50 kDa, 450 kDa) and concentrations (10, 25, 50 mg/L) of PAA up to 7 days. The stability and physical properties of collagen-free PAA-ACP solutions were also investigated. In our system, lowering PAA MW and increasing PAA concentration resulted in solutions with increasing stability. Overstable PAA-ACP solutions that fully inhibited mineralization of the collagen matrices were achieved using PAA 2kDa-50mg/L. Conversely, unstable solutions were obtained using high PAA MW at low concentrations. Nucleation and growth of a significant amount of extrafibrillar minerals on the collagen fibrils was obtained using these solutions. In a wide range of combined MW and concentration of PAA, we obtained intrafibrillar mineralization of collagen with hydroxyapatite crystals aligned parallel to the collagen fibril as in natural tissues. Intrafibrillar mineralization was correlated with PAA-ACP stability and growth of the PAA-ACP particles in solution. Our results support using PAA to act as a surrogate to NCPs function as selective inhibitors or promoters of biological mineralization and provide parameters to manufacture new biomimetic scaffolds and constructs for bone and dentin tissue engineering.

Original languageEnglish (US)
Pages (from-to)2755-2766
Number of pages12
JournalACS Biomaterials Science and Engineering
Volume4
Issue number8
DOIs
StatePublished - Aug 13 2018

Bibliographical note

Funding Information:
This work was supported by the National Nature Science Foundation of China [grant number 81400506], the Medical Science and Technology Research Fund Guangdong Province [grant number A2015304], Clinical Research of Dental Adhesive [grant number CSA-B2015-03]; Innovation Training Program for Undergraduates, Sun Yat-sen University [grant number 201801154] and the National Institute for Dental and Craniofacial Research of the National Institutes of Health [grant number RO1DE026117]. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The funding bodies had no role in study design; the collection, analysis, and interpretation of data; the writing of the report; and the decision to submit the article for publication.

Funding Information:
*Tel.: +1 612-625-4467. Fax: +1 612-626-1484. E-mail: apari003@umn.edu. Address: 16-250A Moos Tower, 515 Delaware St. SE, Minneapolis, MN, USA. ORCID Zhou Ye: 0000-0003-4220-0919 Maria-Pau Ginebra: 0000-0002-4700-5621 Conrado Aparicio: 0000-0003-2969-6067 Funding This work was supported by the National Nature Science Foundation of China [grant number 81400506], the Medical Science and Technology Research Fund, Guangdong Province [grant number A2015304], Clinical Research of Dental Adhesive [grant number CSA-B2015-03]; Innovation Training Program for Undergraduates, Sun Yat-sen University [grant number 201801154], and the National Institute for Dental and Craniofacial Research of the National Institutes of Health [grant number RO1DE026117]. Parts of this work were carried out in the Characterization Facility, University of Minnesota, which receives partial support from NSF through the MRSEC program. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. The funding bodies had no role in study design; the collection, analysis, and interpretation of data; the writing of the report; and the decision to submit the article for publication. Notes The authors declare no competing financial interest.

Publisher Copyright:
© 2018 American Chemical Society.

Keywords

  • amorphous calcium phosphate
  • intrafibrillar biomineralization
  • molecular weight
  • poly(acrylic acid)
  • stabilization

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