Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, United States.
Department of Biomedical Engineering, University of Utah, Salt Lake City, Utah 84112, United States.
ACS Appl Mater Interfaces. 2021 Mar 10;13(9):10942-10951. doi: 10.1021/acsami.0c22302. Epub 2021 Mar 1.
Over the past two decades, the designs of redox polymers have become critical to the field of mediated bioelectrocatalysis and are used in commercial glucose biosensors, as well as other bioelectrochemical applications (e.g., energy harvesting). These polymers are specifically used to immobilize redox mediators on electrode surfaces, allowing for self-exchange-based conduction of electrons from enzymes far from the electrode to the electrode surface. However, the synthesis of redox polymers is challenging and results in large batch-to-batch variability. Herein, we report a rapid entrapment of mediators for NAD-dependent bioelectrocatalysis within reverse ionically condensed polyelectrolytes. A high ionic strength aqueous solution of oppositely charged polyelectrolytes, composed of cationic polyguanidinium (PG) chloride and anionic sodium hexametaphosphate (P6), undergoes phase inversion into a solid microporous polyelectrolyte complex (PEC) when introduced into a low ionic strength aqueous solution. The ionic strength-triggered phase inversion of PGP6 solutions was investigated as a means to entrap mediators on the surface of electrodes for mediated bioelectrocatalysis. Compared to the traditional cross-linked immobilizations using redox polymers, this phase inversion takes place within seconds and requires up to 60 min for complete stabilization. In this work, redox mediator phenazine ethosulfate (PES) was entrapped within PGP6 on electrode surfaces for nicotinamide adenine dinucleotide (NAD)-dependent bioelectrocatalysis. In the bulk solution, NAD-dependent dehydrogenase enzymes catalyze the oxidation of the substrate while reducing NAD to reduced nicotinamide adenine dinucleotide (NADH). The resulting NADH is reoxidized to NAD by the entrapped PES that gets reduced on the electrode, completing the NAD-regeneration-based bioelectrocatalysis. To show the use of these new materials in an application, biofuel cells were evaluated using four different anodic enzyme systems (alcohol dehydrogenase, lactate hydrogenase, glycerol dehydrogenase, and glucose dehydrogenase).
在过去的二十年中，氧化还原聚合物的设计对于介体型生物电化学催化领域变得至关重要，并且被用于商业葡萄糖生物传感器以及其他生物电化学应用（例如能量收集）中。这些聚合物专门用于将氧化还原介质固定在电极表面上，从而允许基于自交换的电子从远离电极的酶传导到电极表面。然而，氧化还原聚合物的合成具有挑战性，并且会导致批次间的变异性很大。在此，我们报告了一种在反向离子凝聚聚电解质中快速捕获NAD 依赖性生物电化学催化所需的介质的方法。由阳离子聚胍盐酸盐（PG）和阴离子六偏磷酸钠（P6）组成的带有相反电荷的聚电解质的高离子强度水溶液，当引入低离子强度水溶液中时，会相变为固体微孔聚电解质复合物（PEC）。研究了 PGP6 溶液的离子强度触发的相反转作为在电极表面上捕获用于介体型生物电化学催化的介质的方法。与使用氧化还原聚合物的传统交联固定化方法相比，这种相反转在几秒钟内发生，并且完全稳定需要长达 60 分钟的时间。在这项工作中，将氧化还原介质吩嗪乙硫磺酸（PES）包埋在电极表面的 PGP6 中，用于烟酰胺腺嘌呤二核苷酸（NAD）依赖性生物电化学催化。在本体溶液中，NAD 依赖性脱氢酶催化底物的氧化，同时将 NAD 还原为还原型烟酰胺腺嘌呤二核苷酸（NADH）。所得的 NADH 通过被还原的 PES 被氧化回 NAD，从而完成基于 NAD 再生的生物电化学催化。为了展示这些新材料在应用中的用途，使用四种不同的阳极酶系统（醇脱氢酶、乳酸脱氢酶、甘油脱氢酶和葡萄糖脱氢酶）评估了生物燃料电池。
