Ishikawa Mariana, Borges Roger, Mourão André, Ferreira Letície Mendonça, Lobo Anderson O, Martinho Herculano
Federal University of ABC, Santo André, São Paulo 09280-560, Brazil.
School of Biomedical Engineering, Faculdade Israelita de Ciências da Saúde Albert Einstein, Hospital Israelita Albert Einstein, São Paulo, São Paulo 09280-560, Brazil.
ACS Omega. 2024 Apr 23;9(18):19796-19804. doi: 10.1021/acsomega.3c08057. eCollection 2024 May 7.
Resorbable polylactic acid (PLA) ultrathin fibers have been applied as scaffolds for tissue engineering applications due to their micro- and nanoporous structure that favor cell adhesion, besides inducing cell proliferation and upregulating gene expression related to tissue regeneration. Incorporation of multiwalled carbon nanotubes into PLA fibers has been reported to increase the mechanical properties of the scaffold, making them even more suitable for tissue engineering applications. Ideally, scaffolds should be degraded simultaneously with tissue growth. Hydration and swelling are factors related to scaffold degradation. Hydration would negatively impact the mechanical properties since PLA shows hydrolytic degradation. Water absorption critically affects the catalysis and allowance of the hydrolysis reactions. Moreover, either mass transport and chemical reactions are influenced by confined water, which is an unexplored subject for PLA micro- and nanoporous fibers. Here, we probe and investigate confined water onto highly porous PLA microfibers containing few amounts of incorporated carbon nanotubes by Fourier transform infrared (FTIR) spectroscopy. A hydrostatic pressure was applied to the fibers to enhance the intermolecular interactions between water molecules and C=O groups from polyester bonds, which were evaluated over the wavenumber between 1600 and 2000 cm. The analysis of temperature dependence of FTIR spectra indicated the presence of confined water which is characterized by a non-Arrhenius to Arrhenius crossover at = 190 K for 1716 and 1817 cm carbonyl bands of PLA. These bands are sensitive to a hydrogen bond network of confined water. The relevance of our finding relies on the challenge detecting confined water in hydrophobic cavities as in the PLA one. To the best of our knowledge, we present the first report referring the presence of confined water in a hydrophobic scaffold as PLA for tissue engineering. Our findings can provide new opportunities to understand the role of confined water in tissue engineering applications. For instance, we argue that PLA degradation may be affected the most by confined water. PLA degradation involves hydrolytic and enzymatic degradation reactions, which can both be sensitive to changes in water properties.
可吸收聚乳酸（PLA）超细纤维已被用作组织工程应用的支架，这是因为其微孔和纳米孔结构有利于细胞粘附，此外还能诱导细胞增殖并上调与组织再生相关的基因表达。据报道，将多壁碳纳米管掺入PLA纤维可提高支架的机械性能，使其更适合组织工程应用。理想情况下，支架应与组织生长同时降解。水合作用和溶胀是与支架降解相关的因素。由于PLA表现出水解降解，水合作用会对机械性能产生负面影响。吸水率严重影响水解反应的催化作用和反应进行。此外，传质和化学反应都受限于水的影响，而这对于PLA微孔和纳米孔纤维来说是一个尚未探索的课题。在此，我们通过傅里叶变换红外（FTIR）光谱对含有少量掺入碳纳米管的高度多孔PLA微纤维中的受限水进行探测和研究。对纤维施加静水压力以增强水分子与聚酯键中C=O基团之间的分子间相互作用，在1600至2000 cm的波数范围内对其进行评估。FTIR光谱的温度依赖性分析表明存在受限水，其特征是在190 K时，PLA的1716和1817 cm羰基带出现从非阿仑尼乌斯到阿仑尼乌斯的转变。这些谱带对受限水的氢键网络敏感。我们这一发现的意义在于，在像PLA这样的疏水性空腔中检测受限水具有挑战性。据我们所知，我们首次报道了在用于组织工程的疏水性支架PLA中存在受限水。我们的发现可为理解受限水在组织工程应用中的作用提供新的机会。例如，我们认为PLA降解可能受受限水的影响最大。PLA降解涉及水解和酶促降解反应，这两者都可能对水性质的变化敏感。
