A novel electrochemical biosensing method with double-layered polymer brush modified electrode

• Published in: Colloids and surfaces, B, Biointerfaces Vol. 222; p. 113105
• Main Authors: Inoue, Yuuki, Kim, Yeji, Hasegawa, Hijiri, Yoshida, Yasukazu, Sakakibara, Keita, Tsujii, Yoshinobu
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.02.2023
• Subjects: Background noise; Biosensing Techniques; Biosensor; DNA; Double-layered structure; Electrodes; Gold; Polymer brush surface; Polymers - chemistry; Wettability; Background noise; Polymer brush surface; Biosensor; DNA; Double-layered structure
• ISSN: 0927-7765; 1873-4367
• DOI: 10.1016/j.colsurfb.2022.113105

We developed a novel electrochemical biosensor electrode that has a potential to reduce background noise for which we constructed an original conductive substrate modified with a double-layered polymer brush structure that is water impermeable and can control biomolecules adsorption/desorption. In this study, a hydrophobic poly(tert-butyl methacrylate) brush layer was prepared on a gold electrode, and then, the tert-butyl group near the outermost surface was dissociated by the acid treatment to obtain a hydrophilic carboxy group, thereby fabricating a conductive substrate with the double-layered polymer brush structure. Formation of the double-layered polymer brush structure was indicated by surface wettability and optical analyses. The potential difference and hydrogen ion concentration, which is a typical parameter of the surrounding environment, were linearly correlated with the gold electrode having a double-layered polymer brush structure with carboxyl groups. However, there was no correlation on gold electrodes with self-assembled monolayers presenting carboxy groups. It is considered that the pH responsiveness of the carboxy groups on the outermost surface could be exhibited remarkably because the charge state in the vicinity of the surface became constant due to the hydrophobic polymer brush layer having a certain thickness. The target DNA could be captured more efficiently at the probe DNA-immobilized electrode with the double-layered polymer brush structure than when using COOH-SAM. This is the first report of the application of the double-layered polymer brush structure for the electrochemical biosensing, and it will be an excellent surface modification method to reduce background noise. [Display omitted] •Electrochemical biosensor electrode with double-layered polymer brush was fabricated.•Hydrophobic layer made potential difference-pH relationship linear at gold electrode.•DNA hybridization on electrode with double-layered polymer brush could be detected.•This method is expected as a modification technique that can reduce background noise.