Rapid and repeatable fabrication of high A/R silk fibroin microneedles using thermally-drawn micromolds.
Thermal drawing is a versatile rapid prototyping method that can freely form microneedle (MN) structures with ultra-high aspect ratio without relying on any complex and expensive process. However, it is still challenging to repeatedly produce MNs with identical shapes using this thermal drawing due to small fluctuations in processing conditions such as temperatures, drawing speeds, drawing heights, or parallelism in the drawing setup. In addition, thermal drawing is only applicable to thermoplastic materials and most natural biomaterials are incompatible with this method. Thus, we propose use of thermal drawing to fabricate master molds with high aspect ratios and replicate the shape by micromolding. In this work, high A/R MNs with various body profiles were fabricated by thermal drawing and replicated to silk fibroin (SF) MNs multiple times using micromolding. The original MN shape was precisely copied to the SF MNs. Methanol treatment enhanced the mechanical strength of SF MNs up to about 113% more depending on the treatment duration. We also demonstrated that methanol exposure time could effectively control drug release rates from SF MNs.
Department of Mechanical Engineering, Yonsei University, Seoul 120-749, Republic of Korea.
JiYong
J
Lee
Department of Mechanical Engineering, Yonsei University, Seoul 120-749, Republic of Korea.
Seung Hyun
SH
Park
Department of Mechanical Engineering, Yonsei University, Seoul 120-749, Republic of Korea.
Il Ho
IH
Seo
Department of Mechanical Engineering, Yonsei University, Seoul 120-749, Republic of Korea.
Kang Ju
KJ
Lee
Department of Mechanical Engineering, Yonsei University, Seoul 120-749, Republic of Korea. Electronic address: whryu@yonsei.ac.kr.
WonHyoung
W
Ryu
D000818:Animals; D002626:Chemistry, Pharmaceutical; D003692:Delayed-Action Preparations; D004337:Drug Carriers; D004867:Equipment Design; D005349:Fibroins / Q000737:chemistry*; D066298:In Vitro Techniques; D007271:Injections, Intradermal; D007700:Kinetics; D008422:Materials Testing; D000432:Methanol / Q000737:chemistry; D008904:Miniaturization; D009339:Needles; D012235:Rhodamines / Q000008:administration & dosage / Q000737:chemistry*; D012867:Skin / Q000378:metabolism; D012995:Solubility; D013499:Surface Properties; D013552:Swine; D013678:Technology, Pharmaceutical / Q000295:instrumentation* / Q000379:methods*; D013696:Temperature
D003692:Delayed-Action Preparations; D004337:Drug Carriers; D012235:Rhodamines; C482288:fibroin, silkworm; D005349:Fibroins; C029773:rhodamine B; D000432:Methanol
Methanol treatment; Micromolding; Microneedles; Silk fibroin; Thermal drawing