具生物相容性、自癒合性質、針頭注射性與雙向致動能力之3D列印水凝膠致動器

Abstract

多功能水凝膠因應新興材料應用的需求，尤其是在具生物相容性的水凝膠致動器方面備受關注。然而，如何同時將韌性、自癒合性質和可逆雙向致動能力整合到具生物相容性的致動器中仍是一項挑戰。在此，利用新型聚（N-異丙基丙烯酰胺）-明膠甲基丙烯酰（PNIPAM-GelMA；“PNG”）水凝膠作為主動層，開發了一種可3D列印、具生物相容性與可逆雙向致動能力的雙層水凝膠致動器。光交聯後的PNG水凝膠展現出自癒合能力，並具備良好的彈性（儲存模量約13 kPa）與韌性（線性黏彈性區間可達240%剪切應變）。小角度X射線散射（Small-Angle X-ray Scattering，SAXS）分析揭示了由互鎖的PNIPAM側鏈組成的動態PNIPAM團簇之存在，這解釋了PNG水凝膠的自癒合行為。以PNG作為主動層、GelMA作為被動層所構成的3D列印雙層水凝膠致動器不僅展現可雙向驅動性能，亦具備針頭可注射性。此外，將 PNG 主動層與具自癒合性質的被動層（例如聚胺酯-GelMA 複合水凝膠）配對，可實現致動器的整體自癒合功能。即便在切斷後修復，該致動器仍能維持顯著的雙向彎曲角度（37 °C時約380°，25 °C時約−270°）。此多功能 PNG系統成功整合韌性、自發性自癒合性質和可逆雙向致動能力，有效地克服了現有具生物相容性的水凝膠致動器之關鍵限制，為開發用於生物醫學應用的致動器提供嶄新進展。

Multifunctional hydrogels are highly desirable for emerging material applications, particularly for biocompatible hydrogel actuators. However, integrating toughness, self-healing, and reversible bidirectional actuation into a biocompatible actuator remains challenging. Herein, a 3D-printable and biocompatible bilayer hydrogel actuator with reversible bidirectional actuation is developed using a new poly(N-isopropylacrylamide)-gelatin methacryloyl (PNIPAM-GelMA; “PNG”) hydrogel as the active layer. The photo-crosslinked PNG hydrogel shows self-healing ability as well as good elasticity (storage modulus ~13 kPa) and toughness (linear viscoelastic range up to 240% shear strain). Small-angle X-ray scattering analysis for microstructure of PNG reveals the presence of dynamic PNIPAM clusters composed of interlocking PNIPAM side chains, accounting for the self-healing behavior of PNG hydrogel. The 3D-printed bilayer actuator with PNG as the active layer and GelMA as the passive layer exhibits bidirectional actuation and fine needle injectability. Moreover, pairing the PNG active layer with a self-healable passive layer (e.g., polyurethane-GelMA composite hydrogel) gives rise to a self-healable actuator. This actuator, repaired upon cutting, retains significant bidirectional bending angles (~380° at 37°C; ~−270° at 25°C). The multifunctional PNG system effectively addresses key limitations of current biocompatible hydrogel actuators by integrating toughness, autonomous self-healing ability, and reversible bidirectional actuation, offering substantial progress in developing actuators for biomedical applications.