Giliomee Johnel, du Toit Lisa C, Klumperman Bert, Choonara Yahya E
Wits Advanced Drug Delivery Platform Research Unit, Department of Pharmacy and Pharmacology, School of Therapeutic Sciences, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, Johannesburg 2193, South Africa.
Department of Chemistry and Polymer Science, Faculty of Science, Stellenbosch University, De Beers Street, Stellenbosch 7600, South Africa.
ACS Omega. 2022 Feb 28;7(9):7556-7571. doi: 10.1021/acsomega.1c05873. eCollection 2022 Mar 8.
The 3D printability of poly(l-lysine--l-alanine) and four-arm poly(ethylene glycol) (P(KA)/4-PEG) hydrogels as 3D biomaterial inks was investigated using two approaches to develop P(KA)/4-PEG into 3D biomaterial inks. Only the "composite microgel" inks were 3D printable. In this approach, P(KA)/4-PEG hydrogels were processed into microparticles and incorporated into a polymer solution to produce a composite microgel paste. Polymer solutions composed of either 4-arm PEG-acrylate (4-PEG-Ac), chitosan (CS), or poly(vinyl alcohol) (PVA) were used as the matrix material for the composite paste. The three respective composite microgel inks displayed good 3D printability in terms of extrudability, layer-stacking ability, solidification mechanism, and 3D print fidelity. The biocompatibility of P(KA)/4-PEG hydrogels was retained in the 3D printed scaffolds, and the biofunctionality of bioinert 4-PEG and PVA hydrogels was enhanced. CS-P(KA)/4-PEG inks demonstrated excellent 3D printability and proved highly successful in printing scaffolds with a narrow strand diameter (∼200 μm) and narrow strand spacing (∼500 μm) while the integrity of the vertical and horizontal pores was maintained. Using different needle IDs and strand spacing, certain physical properties of the hydrogels could be tuned, while the 3D printed porosity was kept constant. This included the surface area to volume ratio, the macropore sizes, and the mechanical properties. The scaffolds demonstrated adequate adhesion and spreading of NIH 3T3 fibroblasts seeded on the scaffold surfaces for 4 days. Consequently, the scaffolds were considered suitable for potential applications in wound healing, as well as other soft tissue engineering applications. Apart from the contribution to new 3D biomaterial inks, this work also presented a new and facile method of processing covalently cross-linked hydrogels into 3D printed scaffolds. This could potentially "unlock" the 3D printability of biofunctional hydrogels, which are generally excluded from 3D printing applications.
研究了聚（L - 赖氨酸 - L - 丙氨酸）和四臂聚乙二醇（P(KA)/4 - PEG）水凝胶作为3D生物材料墨水的3D可打印性，采用两种方法将P(KA)/4 - PEG开发成3D生物材料墨水。只有“复合微凝胶”墨水是3D可打印的。在这种方法中，P(KA)/4 - PEG水凝胶被加工成微粒，并掺入聚合物溶液中以制备复合微凝胶糊剂。由四臂聚乙二醇丙烯酸酯（4 - PEG - Ac）、壳聚糖（CS）或聚乙烯醇（PVA）组成的聚合物溶液用作复合糊剂的基质材料。这三种各自的复合微凝胶墨水在挤出性、层堆叠能力、固化机制和3D打印保真度方面表现出良好的3D可打印性。P(KA)/4 - PEG水凝胶的生物相容性在3D打印支架中得以保留，并且生物惰性的4 - PEG和PVA水凝胶的生物功能得到增强。CS - P(KA)/4 - PEG墨水表现出优异的3D可打印性，并在打印具有窄股线直径（约200μm）和窄股线间距（约500μm）的支架时非常成功，同时保持了垂直和水平孔隙的完整性。使用不同的针内径和股线间距，可以调整水凝胶的某些物理性质，而3D打印的孔隙率保持恒定。这包括表面积与体积比、大孔尺寸和机械性能。支架显示接种在支架表面的NIH 3T3成纤维细胞在4天内有足够的粘附和铺展。因此，这些支架被认为适用于伤口愈合以及其他软组织工程应用中的潜在应用。除了对新型3D生物材料墨水的贡献外，这项工作还提出了一种将共价交联水凝胶加工成3D打印支架的新的简便方法。这可能潜在地“解锁”生物功能水凝胶的3D可打印性，而生物功能水凝胶通常被排除在3D打印应用之外。
