In this study, we fabricated two different microneedles (MNs) — semi-hollow and bird-bill — to overcome the limitations of solid and coated MNs, respectively. The two MN arrays were developed using a general injection molding process to obtain high-quality MNs with uniform shape. The semi-hollow and bird-bill MNs could penetrate the micropores of swine skin up to depths of 178.5 ± 27.6 µm and 232.1 ± 51.3 µm, respectively. When the semi-hollow MNs were used for the transdermal delivery of insulin in diabetic rats, it was observed that the blood glucose concentration (BGC) decreased remarkably within 30 min, and the desired effect of insulin was maintained for an additional 3 h after the removal of insulin from the skin surface. The bird-bill MN was able to load a coating gel at a maximum capacity of 3.20 ± 0.21 mg per MN array, and the BGC continued to decrease significantly after MN application for up to 2–6 h. In summary, we fabricated semi-hollow and bird-bill MN arrays using the injection molding method; these can be mass produced and are capable of effectively producing micro-holes in the stratum corneum. The two MN arrays could provide effective transdermal delivery of large-molecular-weight drugs such as insulin.

在这项研究中，我们制造了两种不同的微针 (MN)——半空心和鸟嘴——分别克服了固体和涂层微针的局限性。两个 MN 阵列是使用通用注塑成型工艺开发的，以获得具有均匀形状的高质量 MN。半空心和鸟嘴 MNs 可以穿透猪皮的微孔，深度分别为 178.5 ± 27.6 µm 和 232.1 ± 51.3 µm。当半空心MNs用于糖尿病大鼠胰岛素的透皮给药时，观察到血糖浓度（BGC）在30分钟内显着下降，并且胰岛素的预期作用在给药后又维持了3小时。从皮肤表面去除胰岛素。鸟嘴 MN 能够以每个 MN 阵列 3.20 ± 0.21 毫克的最大容量加载涂层凝胶，并且在 MN 应用长达 2-6 小时后，BGC 继续显着下降。总之，我们使用注射成型方法制造了半空心和鸟嘴 MN 阵列；这些可以大量生产并且能够有效地在角质层中产生微孔。两个 MN 阵列可以提供大分子量药物（如胰岛素）的有效透皮递送。