Weng Yiming, Dunn Carmen B, Qiang Zhe, Ren Jie
Institute of Nano and Biopolymeric Materials, School of Materials Science and Engineering, Tongji University, Shanghai 201804, China.
School of Polymer Science and Engineering, The University of Southern Mississippi, Hattiesburg, Mississippi 39406, United States.
ACS Appl Mater Interfaces. 2023 Nov 16. doi: 10.1021/acsami.3c11979.
Polylactic acid (PLA) is a biodegradable alternative to petroleum-based polymers for improving environmental sustainability of our society. However, the limited degradation rate and environmental conditions for PLA-based products remain significant challenges for their broader use in various applications. While Proteinase K (Pro K) from has been demonstrated to efficiently degrade PLA, its autocatalytic degradation function in composite films is underexplored. Here, this work reports a strategy that encapsulates Pro K with zeolitic imidazole framework-8 (ZIF-8) in situ, combining a PLA matrix to prepare Pro K@ZIF-8/PLA films through solvent casting. The method is scalable and commercially viable, and the pH and thermal stability of the Pro K enzyme are significantly enhanced after immobilization. The enzyme can retain 61.8% of its initial activity after annealing at 160 °C for 10 min, allowing for its use in the melt processing of filler-containing PLA films. As a result, Pro K@ZIF-8/PLA films in buffer solutions exhibit stable degradation rates, which can be extended to PLA decomposition in acidic environments. Moreover, the enzyme in Pro K@ZIF-8/PLA films prepared by thermoforming remains active sufficiently to degrade PLA with a weight loss of up to 15% in 2 weeks. These results further indicate that our strategy can be broadly applicable for melt processing and controlled degradation of PLA materials with immobilized enzymes, allowing for its transformative impact for promoting environmental sustainability.
聚乳酸（PLA）是一种可生物降解的材料，可替代石油基聚合物，以提高我们社会的环境可持续性。然而，基于PLA的产品降解速率有限以及对环境条件要求较高，这仍然是其在各种应用中更广泛使用的重大挑战。虽然已证明来自[具体来源未提及]的蛋白酶K（Pro K）能有效降解PLA，但其在复合膜中的自催化降解功能尚未得到充分研究。在此，本工作报道了一种策略，即将Pro K与沸石咪唑框架-8（ZIF-8）原位封装，并与PLA基质结合，通过溶液浇铸制备Pro K@ZIF-8/PLA薄膜。该方法具有可扩展性且在商业上可行，固定化后Pro K酶的pH稳定性和热稳定性显著提高。在160℃退火10分钟后，该酶仍能保留其初始活性的61.8%，从而可用于含填料PLA薄膜的熔融加工。结果，Pro K@ZIF-8/PLA薄膜在缓冲溶液中表现出稳定的降解速率，这可扩展至在酸性环境中PLA的分解。此外，通过热成型制备的Pro K@ZIF-8/PLA薄膜中的酶仍具有足够的活性，能够在2周内使PLA降解，失重高达15%。这些结果进一步表明，我们的策略可广泛应用于固定化酶对PLA材料的熔融加工和可控降解，对促进环境可持续性具有变革性影响。
