TY - JOUR
T1 - Ordered micropillar array gold electrode increases electrochemical signature of early biofilm attachment
AU - Astorga, Solange E.
AU - Hu, Liang Xing
AU - Marsili, Enrico
AU - Huang, Yizhong
N1 - Funding Information:
This work was supported by Singapore Centre for Environmental Life Sciences Engineering (SCELSE), whose research is supported by the National Research Foundation Singapore , Ministry of Education , Nanyang Technological University and National University of Singapore , under its Research Centre of Excellence Program. Additional support was provided by Material Science and Engineering, Nanyang Technological University , Tier 1 by the National Research Foundation Singapore , Ministry of Education (MOE) [ M4011959 and M4011528 ]. Solange Elizabeth Astorga was partially supported by a Roberto Rocca fellowship.
Funding Information:
The FESEM results were confirmed by CLSM images. In fact, the distance between features appear to affect biofilm formation, with higher biofilm growth for 12 μm distance than 16 μm, as shown in Fig. 6. As in FESEM images, most bacteria were observed as small aggregates at the foot of pillars. Previous results show preference of bacteria for micropatterned surface at initial attachment [59] and for the grain boundaries of stainless steel [60]. The biomass of the biofilm grown on the 8 μm pillar electrodes was 6.3 ± 2.1 μm3 for viable and 8.9 ± 3.6 μm3 for dead cells, respectively, resulting in a biofilm thickness of 0.40 μm (Fig. 6(a)). In the case of the 4 μm pillar electrodes, the CLSM showed a live cells biomass of 4,3 ± 0.7 μm3 and dead cells biomass of 3.4 ± 0.8 μm3 leading to a biofilm thickness of 0.34 μm (Fig. 6(b)). Both the viable biomass and the biofilm thickness were lower for the 4 μm than for the 8 μm electrodes, which is consistent with the lower current output observed. Overall, the FESEM and CLSM results support the electrochemical data, suggesting that the microstructures on the electrode favor the attachment of the early biofilm onto the electrode, hence the EET is affected as well. Interestingly, the significant difference in biofilm formation among different microstructure does not correlate with the small difference in surface area, indicating that the spatial arrangement of microstructures influences early biofilm formation, rather than the overall surface area of the electrodes.We thank Abeed Mohidin-Batcha for assistance inoculating bacteria, Prasanna Jogdeo for assistance with CLSM imaging, Cao Xun for assistance with FESEM imaging, and Ezequiel Santillan for revising the manuscript. This work was supported by Singapore Centre for Environmental Life Sciences Engineering (SCELSE), whose research is supported by the National Research Foundation Singapore, Ministry of Education, Nanyang Technological University and National University of Singapore, under its Research Centre of Excellence Program. Additional support was provided by Material Science and Engineering, Nanyang Technological University, Tier 1 by the National Research Foundation Singapore, Ministry of Education (MOE) [M4011959 and M4011528]. Solange Elizabeth Astorga was partially supported by a Roberto Rocca fellowship.
Publisher Copyright:
© 2019
PY - 2020/1/5
Y1 - 2020/1/5
N2 - Extracellular electron transfer (EET) from microorganisms to insoluble metals and electrodes is relevant to energy recovery from wastewater, green production of high-added value chemicals, and biosensors for food, environmental, and clinical applications. Microstructured electrode surfaces increase EET rate in bioelectrochemical systems, thus enabling higher sensibility and power output as well as the detection of bacteria and biofilms in bioelectrochemical sensors. However, many aspects of the EET process, particularly in early biofilm stages, are still poorly understood. We report a microstructured gold electrode maintained at oxidative potential to support the growth of Escherichia coli, measure the electrochemical output, and analyze the EET rate during early biofilm formation. The charge outputs of the modified electrodes are up to 22% higher than the control electrodes, enabling the electrochemical detection of early E. coli biofilms. The electrode microstructures promote biofilm attachment, as confirmed by field emission scanning electron microscope (FESEM) and confocal laser scanning microscope (CLSM) imaging. Following biofilm formation, the resistance to charge transfer at the biofilm-electrode interface decreases and the capacitance increases as shown by EIS analysis. Overall, these results contribute to the understanding of EET in early biofilms, towards developing sensitive bioelectrochemical sensors for biofilm detection.
AB - Extracellular electron transfer (EET) from microorganisms to insoluble metals and electrodes is relevant to energy recovery from wastewater, green production of high-added value chemicals, and biosensors for food, environmental, and clinical applications. Microstructured electrode surfaces increase EET rate in bioelectrochemical systems, thus enabling higher sensibility and power output as well as the detection of bacteria and biofilms in bioelectrochemical sensors. However, many aspects of the EET process, particularly in early biofilm stages, are still poorly understood. We report a microstructured gold electrode maintained at oxidative potential to support the growth of Escherichia coli, measure the electrochemical output, and analyze the EET rate during early biofilm formation. The charge outputs of the modified electrodes are up to 22% higher than the control electrodes, enabling the electrochemical detection of early E. coli biofilms. The electrode microstructures promote biofilm attachment, as confirmed by field emission scanning electron microscope (FESEM) and confocal laser scanning microscope (CLSM) imaging. Following biofilm formation, the resistance to charge transfer at the biofilm-electrode interface decreases and the capacitance increases as shown by EIS analysis. Overall, these results contribute to the understanding of EET in early biofilms, towards developing sensitive bioelectrochemical sensors for biofilm detection.
KW - Bioelectrochemistry
KW - Biofilm-surface interaction
KW - Electroactive biofilm
KW - Extracellular electron transfer (EET)
KW - Micropillared electrode
KW - Surface modification
UR - http://www.scopus.com/inward/record.url?scp=85073107711&partnerID=8YFLogxK
U2 - 10.1016/j.matdes.2019.108256
DO - 10.1016/j.matdes.2019.108256
M3 - Article
AN - SCOPUS:85073107711
SN - 0264-1275
VL - 185
JO - Materials and Design
JF - Materials and Design
M1 - 108256
ER -