動脈粥樣硬化是一種典型的動脈疾病，其中最常見之部位，位於提供自身心臟血液的冠狀動脈。傳統上以經皮冠狀動脈腔內成形術，又稱氣球擴張術，來治療血管狹窄，然而有接近三至四成的病患在半年內會發生再狹窄，相較之下，較新穎的藥物塗層球囊大幅降低再狹窄率，但仍存在一些限制，包含藥物選擇受限、藥物釋放不均、術後植入金屬支架再狹窄程度提高和藥物容易被血流沖刷掉等問題，因此創建一種可直接在血管內給藥的裝置顯得重要。本研究主要設計了簡單、低成本和模具可重複使用的空心通道微針製程技術，期望在未來，將其應用於次世代球囊導管上。此空心通道微針利用自組裝模具、複製技術及嵌入聚乙烯醇線材來達成具有四根 26 號經皮針結構，經微電腦斷層掃描儀及流道連接測試證實，此製程技術可實現通道及空心微針的連結，進而使液體從側向流道注入，並從空心微針之洞口輸出。
在材料的選擇上，採用低收縮率且可加熱固化成型之環氧樹脂，透過添加奈米和微米粒子(二氧化鈰、四氧化三鐵)來增強機械性質。在 22 號單根平面空心微針壓縮測試上證實 10 wt.% 二氧化鈰/環氧樹脂和 5 wt.% 四氧化三鐵/環氧樹脂在各自組別 有最好的楊氏模數，且生物相容性上證實此複合物可降低環氧樹脂本身對人類內皮細胞之毒性。在穿刺實驗上透過 26 號經皮針結構之空心微針做假體和豬胸大動脈穿刺，經證實 10 wt.% 二氧化鈰/環氧樹脂具有足夠的機械強度，使空心微針相對完整，而 5 wt.% 四氧化三鐵/環氧樹脂則會使空心微針斷裂，推測是四氧化三鐵之粒徑大小導致顆粒無法均勻分布在模具中，造成針尖前端機械強度不足。此外，在豬胸大動脈穿刺上證實 10 wt.% 二氧化鈰/環氧樹脂在穿刺後有最小的針長度縮減率。由於實驗中仍存在針長度縮減率，因此推測會有微小碎屑留置假體和豬胸大動脈，因此在未來將對針尖結構及材料去做改良，來減少微小碎屑產生。

Atherosclerosis is a typical arterial disease that primarily affects the coronary arteries, which supply blood to the heart. Traditional treatment method for vascular stenosis is percutaneous transluminal coronary angioplasty (PTCA). However, approximately 30% to 40% of patients experience restenosis within six months. Drug-coated balloons (DCBs) have been developed to address this issue, effectively reducing restenosis rates. Nonetheless, there are still limitations associated with DCBs, such as limited drug options, inconsistent drug elution, increased restenosis after metal stent implantation, and susceptibility to drug washout by blood flow. Therefore, developing a device for direct intravascular drug delivery is essential. In this study, our primary objective was to design a simple, low-cost, and mold reusable fabrication technique for hollow channel microneedles (HCMNs), aiming to apply it to next generation balloon catheters in the future. The HCMNs fabrication process involves using assembly molds, replication technique, and embedding of polyvinyl alcohol (PVA) filaments to create four 26G hypodermic needle structures. Micro-CT and fluid testing confirmed the successful connection between the channel and the hollow microneedles (HMNs), allowing lateral channel injection and output from the holes of the HMNs.
Regarding material selection, we used epoxy resin (ER), known for its low shrinking properties and ability to be cured through heating. The mechanical properties were enhanced by adding nanoparticles and microparticles (cerium dioxide (CeO2), ferrosoferric oxide (Fe3O4)). On the 22G single HMN compression tests, confirmed that ER/CeO2-10 wt.% and ER/Fe3O4-5 wt.% exhibited the highest Young's modulus in their respective groups. Furthermore, the biocompatibility tests confirmed that these combinations reduced the toxicity of ER to human endothelial cells (EA.hy926). Penetration testing were conducted using the HMNs with four 26G hypodermic needle structures, simulating puncture on phantoms and the porcine thoracic aorta. The experiments confirmed that ER/CeO2-10 wt.% provided sufficient mechanical strength during phantom penetration, resulting in relatively intact needle tips. In contrast, ER/ Fe3O4-5 wt.% resulted in needle tip fractures. This situation can be attributed to the particle size of Fe3O4, which hindered its effective distribution within the mold, causing insufficient mechanical strength in front of the needle tips. In ex vivo insertion testing using porcine thoracic aorta, indicated that ER/ CeO2-10 wt.% exhibited a minor reduction in needle length after the punctures. Since needle length reduction was observed in the penetration experiments, it is hypothesized that tiny debris may be retained in the phantoms and the porcine thoracic aorta. Therefore, future improvements will focus on modifying the structure and material of the needle tips to minimize the generation of such tiny debris.

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