McCuskey Samantha R, Rengert Zachary D, Zhang Mengwen, Helgeson Matthew E, Nguyen Thuc-Quyen, Bazan Guillermo C
Department of Chemical Engineering, University of California, Santa Barbara, CA, 93106, USA.
Center for Polymers and Organic Solids, University of California, Santa Barbara, CA, 93106, USA.
Adv Biosyst. 2019 Feb;3(2):e1800303. doi: 10.1002/adbi.201800303. Epub 2018 Dec 10.
Synthetic systems that facilitate electron transport across cellular membranes are of interest in bio-electrochemical technologies such as bio-electrosynthesis, waste water remediation, and microbial fuel cells. The design of second generation redox-active conjugated oligoelectrolytes (COEs) bearing terminal cationic groups and a π-delocalized core capped by two ferrocene units is reported. The two COEs, DVFBO and F -DVFBO, have similar membrane affinity, but fluorination of the core results in a higher oxidation potential (422 ± 5 mV compared to 365 ± 4 mV vs Ag/AgCl for the neutral precursors in chloroform). Concentration-dependent aggregation is suggested by zeta potential measurements and confirmed by cryogenic transmission electron microscopy. When the working electrode potential (E ) is poised below the oxidation potential of the COEs (E = 200 mV) in three-electrode electrochemical cells containing Shewanella oneidensis MR-1, addition of DVFBO and F -DVFBO produces negligible biocurrent enhancement over controls. At E = 365 mV, DVFBO increases steady-state biocurrent by 67 ± 12% relative to controls, while the increase with F -DVFBO is 30 ± 5%. Cyclic voltammetry supports that DVFBO increases catalytic biocurrent and that F -DVFBO has less impact, consistent with their oxidation potentials. Overall, electron transfer from microbial species is modulated via tailoring of the COE redox properties.
能够促进电子跨细胞膜传输的合成系统在生物电化学技术中备受关注，如生物电合成、废水处理和微生物燃料电池。本文报道了第二代带有末端阳离子基团和由两个二茂铁单元封端的π-离域核心的氧化还原活性共轭低聚物（COEs）的设计。两种COEs，DVFBO和F -DVFBO，具有相似的膜亲和力，但核心的氟化导致更高的氧化电位（在氯仿中，中性前体相对于Ag/AgCl的氧化电位为422±5 mV，而未氟化的为365±4 mV）。ζ电位测量表明存在浓度依赖性聚集，低温透射电子显微镜证实了这一点。在含有希瓦氏菌MR-1的三电极电化学池中，当工作电极电位（E）设定在低于COEs的氧化电位（E = 200 mV）时，添加DVFBO和F -DVFBO相对于对照产生的生物电流增强可忽略不计。在E = 365 mV时，DVFBO使稳态生物电流相对于对照增加67±12%，而F -DVFBO的增加为30±5%。循环伏安法支持DVFBO增加催化生物电流，而F -DVFBO的影响较小，这与它们的氧化电位一致。总体而言，通过调整COE的氧化还原性质来调节微生物物种的电子转移。
