Department of Physics, University of Kuopio, P.O. Box 1627, FI-70211 Kuopio, Finland.
Colloids Surf B Biointerfaces. 2010 Apr 1;76(2):505-11. doi: 10.1016/j.colsurfb.2009.12.011. Epub 2009 Dec 22.
Polyimide (PI) is a commonly used polymer in microelectronics. Recently, numerous PI-based flexible neural interfaces have been developed for reducing mechanical mismatch between rigid implant and soft neural tissue. Most approaches employ non-photosensitive PI, which has been proven earlier to be biocompatible. However, photosensitive polyimide (PSPI) would simplify device fabrication remarkably, but its biocompatibility has been only sparsely reported. In this study, cytotoxicity of spin-coated PSPI (HD Microsystems PI-2771) and conventional PI (HD Microsystems PI-2525) films were evaluated in vitro using BHK-21 fibroblasts according to the ISO-10993-5 standard. PSPIs were tested as cured at a temperature of 200 degrees C (PI-2771-200) and 350 degrees C (PI-2771-350). The PI film surfaces were characterized in terms of their roughness, energy and zeta potential which are hypothesized to affect cell-material interactions. The values of the total surface free energy (SFE), and its polar and dispersive component, were significantly (p<0.001) greater for the PI-2525 film (SFE: 47.3 mJ/m2) than for the PI-2771-200 (25.6 mJ/m2) or PI-2771-350 films (26.2 mJ/m2). The curing temperature of the PI-2771 had a significant effect on the zeta potential values (p<0.001), but not on surface energy (p=0.091) or roughness (p=0.717). The results from the MTS proliferation assays and live/dead staining revealed that PSPI is almost as non-cytotoxic as conventional PI and polyethylene (negative control). The morphology and spreading of BHK-21 cells were similar on all the PI materials tested. In conclusion, PSPI seems to be a promising biocompatible material, while further studies in vitro and in vivo are needed to clarify the long-term effects.
聚酰亚胺（PI）是微电子学中常用的聚合物。最近，为了减少刚性植入物和柔软的神经组织之间的机械不匹配，已经开发出了许多基于聚酰亚胺的柔性神经接口。大多数方法都采用非光敏性聚酰亚胺（PI），早期已经证明其具有生物相容性。然而，光敏性聚酰亚胺（PSPI）可以极大地简化器件制造，但它的生物相容性却鲜有报道。在这项研究中，根据 ISO-10993-5 标准，使用 BHK-21 成纤维细胞体外评估了旋涂 PSPI（HD Microsystems PI-2771）和常规 PI（HD Microsystems PI-2525）薄膜的细胞毒性。PSPI 分别在 200°C（PI-2771-200）和 350°C（PI-2771-350）下进行了测试。根据其粗糙度、能量和 ζ 电位对细胞-材料相互作用的影响，对 PI 薄膜表面进行了特性描述。假设 PI 薄膜表面的总表面自由能（SFE）及其极性和分散分量对细胞-材料相互作用有影响。PI-2525 薄膜的总表面自由能（SFE）值（47.3 mJ/m2）显著（p<0.001）高于 PI-2771-200（25.6 mJ/m2）或 PI-2771-350 薄膜（26.2 mJ/m2），PI-2771 的固化温度对 ζ 电位值有显著影响（p<0.001），但对表面能（p=0.091）或粗糙度（p=0.717）没有影响。MTS 增殖测定和活/死染色的结果表明，PSPI 几乎与常规 PI 和聚乙烯（阴性对照）一样无细胞毒性。在所有测试的 PI 材料上，BHK-21 细胞的形态和扩散都相似。总之，PSPI 似乎是一种有前途的生物相容性材料，需要进一步的体外和体内研究来阐明其长期影响。
