Spatially discrete thermal drawing of biodegradable microneedles for vascular drug delivery

Chang Kuk Choi, Kang Ju Lee, Young Nam Youn, Eui Hwa Jang, Woong Kim, Byung Kwon Min, Wonhyoung Ryu

Research output: Contribution to journalArticlepeer-review

37 Citations (Scopus)


Spatially discrete thermal drawing is introduced as a novel method for the fabrication of biodegradable microneedles with ultra-sharp tip ends. This method provides the enhanced control of microneedle shapes by spatially controlling the temperature of drawn polymer as well as drawing steps and speeds. Particular focus is given on the formation of sharp tip ends of microneedles at the end of thermal drawing. Previous works relied on the fracture of polymer neck by fast drawing that often causes uncontrolled shapes of microneedle tips. Instead, this approach utilizes the surface energy of heated polymer to form ultra-sharp tip ends. We have investigated the effect of such temperature control, drawing speed, and drawing steps in thermal drawing process on the final shape of microneedles using biodegradable polymers. XRD analysis was performed to analyze the effect of thermal cycle on the biodegradable polymer. Load-displacement measurement also showed the dependency of mechanical strengths of microneedles on the microneedle shapes. Ex vivo vascular tissue insertion and drug delivery demonstrated microneedle insertion to tunica media layer of canine aorta and drug distribution in the tissue layer.

Original languageEnglish
Pages (from-to)224-233
Number of pages10
JournalEuropean Journal of Pharmaceutics and Biopharmaceutics
Issue number2
Publication statusPublished - 2013 Feb

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Pharmaceutical Science


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