可降解聚胺酯水膠及大豆蛋白混合膠3D生物列印

Abstract

3D列印製備組織工程客製化支架是一項極具潛力的加工技術。其中以水膠材料作為生物列印墨水結合細胞列印更可以提供基礎研究及未來醫學治療生物平台。在本研究中，製備三種水性生物可降解聚己內酯(poly(ε-caprolactone), PCL)基底的聚胺酯(polyurethane, PU)奈米水分散液，其PU流體-膠體(sol-gel)的相轉變會受到溫度及電解質影響，以動態光散射(dynamic light scattering, DLS)、小角度X-ray散射(small angle X-ray scattering, SAXS)、X-ray繞射(X-ray diffraction, XRD)及流變學(rheology)等分析方法探討凝膠行為及成膠機制。PU軟鏈段中由20 mol% L型聚乳酸二元醇(poly (L-lactide) , PLLA diol)或DL型聚乳酸二元醇(poly (D,L-lactide), PDLLA diol)及80 mol% PCL二元醇所組成之奈米分散液可在高於37°C時形成緊密堆積的結構。PLLA-PCL軟鏈段組成之PU對溫度提升較有響應性，而PDLLA-PCL軟鏈段組成的PU對額外添加的電解質較為敏感。具有溫感性的PU分散液可於3分鐘內成膠並在30分鐘後達到膠體模數6-8 kPa。此PU水膠可藉由預熱及均勻混合細胞製備生物列印墨水，並於37°C平台3D列印。另外，更進一步引入大豆分離蛋白(soy protein isolate, SPI)製備PU混合膠(PU/SPI hybrid)以增加列印過程中的結構堆疊完整性。PU/SPI混合膠相較於PU有較低的黏度，卻可在37°C更快速的成膠並在1分鐘內達到130 Pa的膠體模數。且PU/SPI hybrid可省去預熱過程直接在室溫(25°C)混入細胞並於37°C直接進行列印。48小時細胞培養在PU/SPI hybrid比純PU膠中有較佳的細胞相容性。此種由SPI與溫度敏感性PU形成的混合膠可能是未來生物3D列印具潛力新型的生物列印墨水。

3D printing technique shows great promises for fabricating customized structural scaffolds for tissue regeneration. Using hydrogel as bioink for cell printing provides a biological platform for basic research and potential medical treatment. In this study, the waterborne dispersions of poly(ε-caprolactone) (PCL)-based biodegradable polyurethane (PU) nanoparticles were prepared. The sol-gel transition of the PU dispersions affected by temperature or electrolytes was examined by dynamic light scattering (DLS), small angle X-ray scattering (SAXS), X-ray diffraction (XRD), and rheology. The dispersion of PU nanoparticles with 20 mol% poly (L-lactide) (PLLA) diol or poly (D,L-lactide) (PDLLA) diol and 80 mol% PCL diol in soft segement composition could form compact packing structure at temperatures ≥37°C. The dispersion of PU with PLLA-PCL soft segment was more responsive to the temperature increase, while that with PDLLA-PCL soft segment was more responsive to the added electrolytes. With thermally-responsive properties, both PU dispersions could gel in 3 min with the gel modulus increased to about 6-8 kPa after 30 min. PU hydrogels were preheated and blended with cells, and the mixture was later printed at 37°C. The hybrid hydrogel of PU and soy protein isolate (PU/SPI hybrid) was further developed to enhance the structural integrity of the cell-laden constructs during deposition. The viscosity of the PU/SPI hybrid was lower than that of PU gel, but could undergo rapid gelation at 37°C with modulus increased to 130 Pa in 1 min. Moreover, the PU/SPI hybrid gel may be directly mixed with cells at room temperature and subsequently printed at 37°C without preheating. Cells cultured in the PU/SPI hybrid gel for 48 h proliferated faster than those in PU gel. The hybrid gel made of thermoresponsive PU and SPI may be a new type of bioink for 3D biopriniting applications.