Single-walled carbon nanotube (SWNT) has gained significant interest as a transducer in various electrochemical sensing devices due to their unique structure, compatibility with biomolecules, and excellent electronic properties. As-prepared SWNTs are usually a mixture of semiconducting and metallic ones. Despite of the higher content of semiconducting components in mixed SWNTs, metallic properties are predominantly expressed due to the bundling issue of the SWNT during the fabrication process, limiting the applicability to bio-transistor application. Here, we present a multi-scale semiconducting electronic film of SWNTs as a transducing platform for electrochemical field-effect-transistor (eFET) suitable for the sensitive detection of subtle biological modulation. A genetically engineered filamentous M13 phage showing strong binding affinity toward SWNTs on its body surface was used as a biological material, allowing us to fabricate a large-scale transparent semiconducting nanocomposite. As the relative ratio of SWNT to M13 phage decreases, the on–off ratio of SWNT electronic film increases by 1200%. To show broad applicability, the multi-scale SWNT nanomesh-based eFET is applied for monitoring a variety of biological reactions in association with enzymes, aptamers, and even cyanobacteria. The biomimetic electronic material system with the capability of transducing biological responses at a large scale over a broad dynamic range holds excellent promise for biosensors, biofuel cells, and environment monitoring.

Electrochemical field-effect bio-transistor based on a multi-scale electronic nanomesh of single-walled carbon nanotubes
    Abstract
    1 Introduction
    2 Experimental section
        2.1 Fabrication of SWNT electronic nanomesh
        2.2 Fabrication of the nanomesh-based eFET biosensors
        2.3 Characterization and measurement 
    3 Results and discussion
    4 Conclusion
    Acknowledgements 
    References

• Seung‑Woo Lee(Department of Fine Chemistry, Seoul National University of Science and Technology, 232 Gongneung‑Ro, Nowon‑gu, Seoul 01811, Korea, Center for Functional Biomaterials, Seoul National University of Science and Technology, 232 Gongneung‐ro, Nowon‐gu, Seoul 01811, Korea)
• Ki‑Sung Cheon(Department of Fine Chemistry, Seoul National University of Science and Technology, 232 Gongneung‑Ro, Nowon‑gu, Seoul 01811, Korea)
• Hyunseok Lee(Department of Fine Chemistry, Seoul National University of Science and Technology, 232 Gongneung‑Ro, Nowon‑gu, Seoul 01811, Korea)
• Kyowook Hwang(Department of Fine Chemistry, Seoul National University of Science and Technology, 232 Gongneung‑Ro, Nowon‑gu, Seoul 01811, Korea)
• Eun‑Hee Lee(Department of Microbiology, Pusan National University, 2 Busandaehak‐ro 63 Beon‐gil, Geumjeong‐gu, Busan 46241, Korea)