Bisphosphonic Acid-Functionalized Cross-Linkers to Tailor Hydrogel Properties for Biomedical Applications


Guven M. N. , Altuncu M. S. , Bal T., Oran D. C. , Gulyuz U., Kizilel S., ...More

ACS OMEGA, vol.3, no.8, pp.8638-8647, 2018 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 3 Issue: 8
  • Publication Date: 2018
  • Doi Number: 10.1021/acsomega.8b01103
  • Title of Journal : ACS OMEGA
  • Page Numbers: pp.8638-8647

Abstract

Two bisphosphonic acid-functionalized cross-linkers (one novel) with different spacer chain characteristics were synthesized and incorporated into hydrogels by copolymerization with 2-hydroxyethyl methacrylate at different ratios to control the hydrogels' swelling, mechanical properties, and ability to support mineralization for biomedical applications. The cross-linkers were synthesized by reaction of 2-isocyanatoethyl methacrylate and bisphosphonated diamines followed by selective dealkylation of the bisphosphonate ester groups. The hydrogels provide in vitro growth of carbonated apatite, morphology affected by the cross-linker structure. The hydrogels exhibit a high Young's modulus E (up to 400 kPa) and can sustain up to 10.2 +/- 0.1 MPa compressive stresses. E and hence the cross-link density significantly increases upon mineralization reflecting the formation of many bisphosphonate BP-Ca2+ bonds acting as additional cross-links. Cyclic mechanical tests reveal self-recoverability of hydrogels because of reversible nature of BP-Ca2+ bonds. The results suggest that these cross-linkers can add calcium-binding abilities to hydrogels synthesized from any monomer and improve their mechanical, swelling, and mineralization properties and hence are potentially useful materials for biomedical applications.