This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.104.056747v1 89/1/536    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Gutsmann, T. Articles by Hansma, P. K. Search for Related Content PubMed PubMed Citation Articles by Gutsmann, T. Articles by Hansma, P. K.

Sacrificial Bonds in Polymer Brushes from Rat Tail Tendon Functioning as Nanoscale Velcro

Department of Physics, University of California, Santa Barbara, California 93101

Correspondence: Address reprint requests to Thomas Gutsmann, Tel.: 49-0-4537-188 291; Fax: 49-0-4537-188 632; E-mail: tguts{at}fz-borstel.de.

Polymers play an important role in many biological systems, so a fundamental understanding of their cross-links is crucial not only for the development of medicines but also for the development of biomimetic materials. The biomechanical movements of all mammals are aided by tendon fibrils. The self-organization and biomechanical functions of tendon fibrils are determined by the properties of the cross-links between their individual molecules and the interactions among the cross-links. The cross-links of collagen and proteoglycan molecules are particularly important in tendons and, perhaps, bone. To probe cross-links between tendon molecules, we used the cantilever tip of an atomic force microscope in a pulling setup. Applying higher forces to rat tail tendon molecules with the tip led to a local disruption of the highly organized shell of tendon fibrils and to the formation or an increase of a polymer brush of molecules sticking out of the surface. The cross-linking between these molecules was influenced by divalent Ca²⁺ ions. Furthermore, the molecules of the polymer brush seemed to bind back to the fibrils in several minutes. We propose that sacrificial bonds significantly influence the tendon fibrils' self-organization and self-healing and therefore contribute to toughness and strength.