Surface modification of exoelectrogens with photoelectric materials is a promising way for achieving photo-assisted microbial fuel cells (MFCs). However, the poor conductivity of most photoelectric materials inevitably hampers the electron transfer inside bacterial biofilms. Herein, by utilizing the electrostatic layer-by-layer assembly strategy, the conductive Au nanoparticles (NPs) and photo-responsive CdS NPs were alternatively modified onto the surface of Escherichia coli for photo-assisted bioanodes in MFCs. The CdS layer was found to protect the bacterial cells from light illumination-induced inactivation. When the CdS layer coexisted with an outer layer of Au NPs, the modification of the CdS layers can generate photocurrent without any loss of biocurrent, because the outer Au layer could serve as a conductive channel for the photoelectron and bioelectron transfer between each bacterium. But the increase of CdS layers failed to further improve the photocurrent, implying that the light was inaccessible to the inner CdS layer. This work brings a universal way to fabricate conductive and photo-responsive bacteria, which would deepen the application of cell-surface modification technology in photo-assisted MFCs.

中文翻译：

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用于细菌燃料电池光辅助生物阳极的细菌细胞表面上的Au和CdS纳米颗粒的逐层组装

用光电材料对外生电子进行表面改性是实现光辅助微生物燃料电池（MFC）的一种有前途的方法。但是，大多数光电材料的电导率差不可避免地会阻碍细菌生物膜内部的电子转移。本文中，通过利用静电逐层组装策略，将导电金纳米颗粒（NPs）和光敏CdS NPs交替修饰到大肠杆菌表面上用于MFC中的光辅助生物阳极。发现CdS层可以保护细菌细胞免受光照诱导的失活。当CdS层与Au NPs的外层共存时，CdS层的修饰可以产生光电流而不会损失任何生物电流，因为Au的外层可以充当每个细菌之间光电子和生物电子转移的导电通道。但是CdS层的增加不能进一步改善光电流，这意味着内部CdS层无法进入光。这项工作带来了一种制造导电细菌和光响应细菌的通用方法，这将加深细胞表面修饰技术在光辅助MFC中的应用。