具3D列印性之熱響應甲基丙烯醯基明膠-聚異丙基丙烯醯胺水凝膠之仿生雙層水凝膠致動器研究

Abstract

開發可編程形變的水凝膠系統致動器是一個非常重要的議題，並已引起基礎和應用研究的高度關注。大部分的致動器是不可降解或不能在生理環境下運行的。在此，探索具熱響應和可生物降解的甲基丙烯醯基明膠-聚異丙基丙烯醯胺水凝膠 (即GN水凝膠) 網絡作為雙層水凝膠的主動層。以小角度X光散射顯示GN水凝膠在溫度導致之相變時形成中球體結構 (約230 Å)，並由流變數據支持GN水凝膠有三維 (3D) 列印性和可調控的機械性質。通過改變層厚度來優化由主動GN和被動GelMA層組成的雙層水凝膠致動器，以實現曲率約為5.5 cm-1的大、異向性和可重複的彎曲。在塊狀製造的過程中，不同圖案的主動層被設計用於可編程控制的驅動。3D列印的GN水凝膠結構根據其結構設計減少約25-60%的體積，並由37 °C的熱觸發驅動得到更好的解析度，當置於室溫下能完全再次溶脹。更複雜的3D列印蝴蝶致動器展示了通過熱響應來模擬翅膀動作的能力。此外，GN水凝膠中的成肌細胞在14天內表現出約376%的顯著增殖。這項研究為開發用於生物醫學應用的仿生設備、軟機器人和人造肌肉提供一種新的製造策略。

Development of hydrogel-based actuators with programmable deformation is an important issue that arouses high attention in fundamental and applied research. Most of these actuators are non-biodegradable or work under non-physiological conditions. Herein, a thermoresponsive and biodegradable gelatin methacryloyl (GelMA)-poly(N-isopropyl acrylamide) hydrogel (i.e., GN hydrogel) network was explored as the active layer of a bilayer actuator. Small-angle X-ray scattering (SAXS) showed that GN hydrogel formed mesoglobular structures (~ 230 Å) upon thermally induced phase transition. Rheological data supported that GN hydrogel had 3D printability and tunable mechanical properties. A bilayer hydrogel actuator composed of active GN and passive GelMA layers was optimized by varying the layer thickness and compositions to achieve large, anisotropic, and reproducible deformation with a curvature ~ 5.5 cm-1. Different active layer patterns of the bilayer hydrogel were designed for actuation in programmable control. The 3D printed GN hydrogel structures reduced ~ 25-60% volume depending on the structure design and gained better resolution at 37 °C due to thermo-triggered actuation, while were able to fully reswell at room temperature. A more intricate 3D printed butterfly actuator displayed the ability to mimic the wing movement through thermoresponsiveness. In addition, myoblasts laden in GN hydrogel exhibited significant proliferation of ~ 376% in 14 days. This study provides a new fabrication strategy for developing soft robotics, biomimetic devices, and artificial muscles for biomedical applications.