Microbially produced polyhydroxyalkanoates (PHAs) are polyesters that are degradable by naturally occurring enzymes. Albeit PHAs degrade slowly when implanted in animal models, their disintegration is faster compared to abiotic hydrolysis under simulated physiological environments. Ultrathin Langmuir‐Blodgett (LB) films are used as models for fast in vitro degradation testing, to predict enzymatically catalyzed hydrolysis of PHAs in vivo. The activity of mammalian enzymes secreted by pancreas and liver, potentially involved in biomaterials degradation, along with microbial hydrolases is tested toward LB‐films of two model PHAs, poly(3‐R‐hydroxybutyrate) (PHB) and poly[(3‐R‐hydroxyoctanoate)‐co‐(3‐R‐hydroxyhexanoate)] (PHOHHx). A specific PHA depolymerase from Streptomyces exfoliatus, used as a positive control, is shown to hydrolyze LB‐films of both polymers regardless of their side‐chain‐length and phase morphology. From amorphous PHB and PHOHHx, ≈80% is eroded in few hours, while mass loss for semicrystalline PHB is 25%. Surface potential and interfacial rheology measurements show that material dissolution is consistent with a random‐chain‐scission mechanism. Degradation‐induced crystallization of semicrystalline PHB LB‐films is also observed. Meanwhile, the surface and the mechanical properties of both LB‐films remain intact throughout the experiments with lipases and other microbial hydrolases, suggesting that non‐enzymatic hydrolysis could be the predominant factor for acceleration of PHAs degradation in vivo.

中文翻译：

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解聚酶和脂肪酶对Langmuir降解研究中确定的聚羟基链烷酸酯降解的影响

微生物生产的聚羟基链烷酸酯（PHA）是可被天然酶降解的聚酯。尽管PHA植入动物模型后降解缓慢，但与在模拟生理环境下进行非生物水解相比，它们的分解速度更快。超薄Langmuir-Blodgett（LB）膜用作快速体外降解测试的模型，以预测体内PHAs的酶催化水解。对两种模型PHAs的LB膜（聚（3-‐ R-羟基丁酸酯）（PHB）和聚[（3- R）的LB膜）进行测试，胰腺和肝脏分泌的可能与生物材料降解有关的哺乳动物酶的活性以及微生物水解酶。-羟基辛酸酯）-co-（3- R-羟基己酸酯）]（PHOHHx）。链霉菌的一种特定的PHA解聚酶用作阳性对照的，无论其侧链长度和相形态如何，均可水解两种聚合物的LB膜。非晶质PHB和PHOHHx在数小时内被侵蚀了约80％，而半晶质PHB的质量损失为25％。表面电势和界面流变学测量表明，物质溶解与随机断链机制一致。还观察到半结晶PHB LB膜的降解诱导结晶。同时，在使用脂肪酶和其他微生物水解酶进行的整个实验中，两张LB膜的表面和力学性能均保持不变，这表明非酶水解可能是促进体内PHA降解的主要因素。