Advanced Materials, Nuclear Technology and Applied Bio/Nanotechnology , Consolidated Research Unit UIC-154, University of Burgos , Hospital del Rey s/n, 09001 Burgos , Castilla y León, Spain.
ACS Appl Mater Interfaces. 2018 May 30;10(21):18170-18182. doi: 10.1021/acsami.7b18844. Epub 2018 May 16.
The modification of carbon nanomaterials with biological molecules paves the way toward their use in biomedical and biotechnological applications, such as next-generation biocatalytic processes, development of biosensors, implantable electronic devices, or drug delivery. In this study, different commercial graphene derivatives, namely, monolayer graphene oxide (GO), graphene oxide nanocolloids (GOCs), and polycarboxylate-functionalized graphene nanoplatelets (GNs), were compared as biomolecule carrier matrices. Detailed spectroscopic analyses showed that GO and GOC were similar in composition and functional group content and very different from GN, whereas divergent morphological characteristics were observed for each nanomaterial through microscopy analyses. The commercial α-l-rhamnosidase RhaB1 from the probiotic bacterium Lactobacillus plantarum, selected as a model biomolecule for its relevant role in the pharma and food industries, was directly immobilized on the different materials. The binding efficiency and biochemical properties of RhaB1-GO, RhaB1-GOC, and RhaB1-GN composites were analyzed. RhaB1-GO and RhaB1-GOC showed high binding efficiency, whereas the enzyme loading on GN, not tested in previous enzyme immobilization studies, was low. The enzyme showed contrasting changes when immobilized on the different material supports. The effect of pH on the activity of the three RhaB1-immobilized versions was similar to that observed for the free enzyme, whereas the activity-temperature profiles and the response to the presence of inhibitors varied significantly between the RhaB1 versions. In addition, the apparent K for the immobilized and soluble enzymes did not change. Finally, the free RhaB1 and the immobilized enzyme in GOC showed the best storage and reutilization stability, keeping most of their initial activity after 8 weeks of storage at 4 °C and 10 reutilization cycles, respectively. This study shows, for the first time, that distinct commercial graphene derivatives can influence differently the catalytic properties of an enzyme during its immobilization.
生物分子对碳纳米材料的修饰为其在生物医学和生物技术应用中的应用铺平了道路，例如下一代生物催化过程、生物传感器的开发、可植入电子设备或药物输送。在这项研究中，比较了不同的商业石墨烯衍生物，即单层氧化石墨烯（GO）、氧化石墨烯纳米胶体（GOC）和多羧基功能化石墨烯纳米片（GN），作为生物分子载体基质。详细的光谱分析表明，GO 和 GOC 在组成和官能团含量上相似，与 GN 非常不同，而通过显微镜分析观察到每种纳米材料的形态特征不同。选择来自益生菌植物乳杆菌的α-l-鼠李糖苷酶 RhaB1 作为模型生物分子，因其在制药和食品工业中的相关作用，直接固定在不同的材料上。分析了 RhaB1-GO、RhaB1-GOC 和 RhaB1-GN 复合材料的结合效率和生化特性。RhaB1-GO 和 RhaB1-GOC 表现出较高的结合效率，而在以前的酶固定化研究中未测试的 GN 的酶负载量较低。当固定在不同的材料载体上时，酶表现出相反的变化。三种 RhaB1 固定化版本的 pH 对活性的影响与游离酶观察到的相似，而活性-温度曲线和对抑制剂存在的反应在 RhaB1 版本之间差异显著。此外，固定化和可溶酶的表观 K 没有变化。最后，游离的 RhaB1 和 GOC 中的固定化酶表现出最佳的存储和再利用稳定性，在 4°C 下储存 8 周和 10 次再利用循环后，分别保持其初始活性的大部分。这项研究首次表明，不同的商业石墨烯衍生物在固定化过程中可以不同程度地影响酶的催化特性。
