Choi Chang Kuk, Lee Kang Ju, Youn Young Nam, Jang Eui Hwa, Kim Woong, Min Byung-Kwon, Ryu WonHyoung
School of Mechanical Engineering, Yonsei University, Seoul, Republic of Korea.
Division of Cardiovascular Surgery, School of Medicine, Yonsei University, Seoul, Republic of Korea.
Eur J Pharm Biopharm. 2013 Feb;83(2):224-33. doi: 10.1016/j.ejpb.2012.10.020. Epub 2012 Nov 29.
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.
空间离散热拉伸被引入作为一种制造具有超尖尖端的可生物降解微针的新方法。该方法通过在空间上控制拉伸聚合物的温度以及拉伸步骤和速度，增强了对微针形状的控制。特别关注热拉伸结束时微针尖锐尖端的形成。以往的工作依赖于通过快速拉伸使聚合物颈部断裂，这往往会导致微针尖端形状失控。相反，这种方法利用加热聚合物的表面能来形成超尖的尖端。我们使用可生物降解聚合物研究了热拉伸过程中这种温度控制、拉伸速度和拉伸步骤对微针最终形状的影响。进行XRD分析以分析热循环对可生物降解聚合物的影响。负载 - 位移测量也显示了微针机械强度对微针形状的依赖性。体外血管组织插入和药物递送证明微针可插入犬主动脉的中膜层并在组织层中进行药物分布。
