In vivo evaluation of injectable thermosensitive polymer with time-dependent LCST

Eric Henderson, Bae Hoon Lee, Zhanwu Cui, Ryan McLemore, Tedd A. Brandon, Brent Vernon

Research output: Contribution to journalArticlepeer-review

26 Scopus citations


The focus of this study was to examine the biocompatibility, time-dependent LCST, and bioerodable properties of a copolymer system composed of NIPAAm, dimethyl-γ-butyrolactone (DMBL), and acrylic acid (AAc). Sprague Dawley rats were subcutaneously injected with 25 wt % solutions of poly(NIPAAm-co-DMBL- co-AAc). At predetermined times, animals were sacrificed and polymer implants were recovered for characterization via 1H-NMR. In addition, polymer-contacting tissue sections were harvested and processed for histology. The biocompatibility of the implants was assessed by counting the number of fibroblasts and leukocytes present at the tissue-implant interface. The LCST data obtained from the in vivo implants was shown to agree with that of in vitro findings. Implant mass was shown to decrease after 4 days, indicating accelerated diffusion rates with increased implant swelling, hydrolytic degradation was confirmed with 1H-NMR measurements. The cellular presence at the copolymer implant-tissue interface was shown to return to that of normal tissue 30 days postimplantation, which suggests a normal wound healing response.

Original languageEnglish (US)
Pages (from-to)1186-1197
Number of pages12
JournalJournal of Biomedical Materials Research - Part A
Issue number4
StatePublished - Sep 15 2009


  • Bioresorption
  • Hydrogel
  • Hydrolysis
  • Thermally responsive material

ASJC Scopus subject areas

  • Ceramics and Composites
  • Biomaterials
  • Biomedical Engineering
  • Metals and Alloys


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