Yui Sasaki

Selective nitrate detection by an enzymatic sensor based on an extended-gate type organic field-effect transistor

First selective nitrate biosensor device based on an extended-gate type organic field-effect transistor (OFET) is reported. The fabricated sensor device consists of the extended-gate electrode functionalized by a nitrate reductase with a mediator (=a bipyridinium derivative) and an OFET-based transducer. The mechanism of the nitrate detection can be explained by an electron-relay on the extended-gate electrode, resulting in changes of the electric properties of the OFET. The detection limit of nitrate in water is estimated to be 45 ppb, which suggests that the sensitivity of our fabricated sensor is comparable to those of some conventional detection methods. As a practical application of the OFET sensor, the nitrate detection in diluted human saliva has been successfully demonstrated; the results agreed well with those by conventional colorimetric measurement. The advantages of OFETs are printability, mechanical flexibility, stretchability and disposability, meaning that the fabricated OFET could open up a new approach for low-cost electronic devices toward on-site detection of nitrate in aqueous media.

An Organic Field-effect Transistor with an Extended-gate Electrode Capable of Detecting Human Immunoglobulin A.

We herein report on the development of an extended-gate type organic field-effect transistor (OFET)-based immunosensor for the detection of human immunoglobulin A (IgA). The titration results of IgA exhibited shifts in the transfer characteristics of the OFET sensor device with increasing IgA concentration. A linear detection range from 0 to 10 μg/mL was realized with a detection limit of 2.1 μg/mL, indicating that the OFET-based immunosensor can be potentially applied to the monitoring of infectious diseases and psychological stress in daily life.

Label-Free Detection of Human Glycoprotein (CgA) Using an Extended-Gated Organic Transistor-Based Immunosensor

Herein, we report on the fabrication of an extended-gated organic field-effect transistor (OFET)-based immunosensor and its application in the detection of human chromogranin A (hCgA). The fabricated OFET device possesses an extended-gate electrode immobilized with an anti-CgA antibody. The titration results of hCgA showed that the electrical changes in the OFET characteristics corresponded to the glycoprotein recognition ability of the monoclonal antibody (anti-CgA). The observed sensitivity (detection limit: 0.11 µg/mL) and selectivity indicate that the OFET-based immunosensor can be potentially applied to the rapid detection of the glycoprotein concentration without any labeling.

Development of polymer field-effect transistor-based immunoassays

AbstractPolymer field-effect transistors (PFETs) are among the most fascinating electronic devices because of their attractive properties, such as durability, environmental friendliness, and solution processability. To date, PFETs have been employed for the development of flexible displays, radio-frequency identification tags, flexible non-volatile memories, among others. Moreover, due to the above advantages, PFETs can be applied to disposable on-site analytical devices. In that regard, we have developed extended-gate type PFETs with molecular recognition biomaterials for protein sensing in aqueous media. The fabricated PFETs were used to successfully detect glycoproteins (immunoglobulin A, immunoglobulin G, and chromogranin A) without any complicated labeling processes. Since our proposed immunoassay, which is performed on the basis of extended-gate type PFETs, is rapid and easy-to-use, PFET will be an attractive platform for on-site monitoring devices in healthcare applications in the near future.We have successfully developed easy-to-use and rapid immunosensor devices based on extended-gate type polymer field-effect transistors (PFETs). The designed PFET was operated under low-voltage conditions, being able to apply for the detection of proteins in water. As a consequence, label-free detection of glycoproteins was achieved by the extended-gate PFETs functionalized with monoclonal or polyclonal antibodies. We believe that PFET-based immunoassays will be an attractive platform for on-site monitoring devices in healthcare applications in the near future.

Cover Picture: Label-Free Direct Electrical Detection of a Histidine-Rich Protein with Sub-Femtomolar Sensitivity using an Organic Field-Effect Transistor (ChemistryOpen 4/2017)

The Front Cover picture shows an electrical bioassay for the label‐free and highly‐sensitive detection of a histidine‐rich protein (serum albumin) using an organic filed‐effect transistor (an OFET) modified with a NiII‐trinitriloacetic acid monolayer (NiII‐nta). More information can be found in the Communication by T. Minamiki et al. on page 472 in Issue 6, 2017 (DOI: 10.1002/open.201700070).