Degradation and adhesive/cohesive strengths of a reservoir-based drug eluting stent

W. L. Shan, J. Du, E. P. Hampp, H. Li, M. Johnson, G. Papandreou, C. A. Maryanoff, W. O. Soboyejo

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


This paper presents the results of loss of mechanical strengths due to the degradation that occurs in a model reservoir-based coronary stent, the NEVO Sirolimus-eluting Stent (NEVO SES). The adhesion of the formulation to the reservoir and cohesion within the formulation in the time course of hydrolysis were determined using a micro-testing system that was developed specifically for the measurements of the adhesive and cohesive strengths of suspended polymeric films. The strengths were measured after hydration, during degradation with gentle agitation, as well as degradation with pulsatile mechanical loading. The morphology and molecular weight changes in the time course of NEVO SES formulation degradation were also studied using Scanning Electron Microscopy (SEM) and Gel Permeation Chromatography (GPC) techniques. Morphological changes, such as pore formation, lagged behind the decrease in the molecular weight of the formulation. In contrast, the adhesion/cohesion strengths showed that the mechanical integrity of the stents dropped significantly within a few hours of hydration, before reaching a plateau. Despite the significant molecular weight decrease and morphological changes, the plateau mechanical strengths reached were essentially the same during degradation, under both, mechanically unloaded and loaded conditions.

Original languageEnglish (US)
Pages (from-to)208-215
Number of pages8
JournalJournal of the Mechanical Behavior of Biomedical Materials
StatePublished - 2012
Externally publishedYes


  • Adhesive/cohesive strengths
  • Degradation
  • Drug eluting stents
  • Hydrolysis
  • Molecular weight
  • Morphology

ASJC Scopus subject areas

  • Biomaterials
  • Biomedical Engineering
  • Mechanics of Materials


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