Covalent conjugation of glucose oxidase on single-walled carbon nanotubes for glucose sensing

Glucose sensing and monitoring are crucial for biological and medical applications. Compared to existing methods, real-time detection and long-term monitoring are still required. Single-walled carbon nanotubes (SWCNTs) have excellent optical properties for sensing applications, which provide the possibility for designing a new generation of glucose sensors. In this study, we describe a method for covalently conjugate glucose oxidase (GOx) on SWCNTs as an optical glucose sensor. The functional groups are introduced by a photocatalytic reaction which acts as the handle for protein loading on SWCNTs. In this sp3 defect reaction, the optical properties of SWCNTs can be maintained. With a convenient bioconjugation reaction, the GOx could be covalently linked with SWCNTs. Compared to the non-covalent immobilization conjugates, the covalent conjugate sensor exhibits a much stronger optical response toward glucose, and the stability of the biosensor also increases in harsh conditions. At the same time, we also report the changing ratio of the original E 11 and defected E 11 * peak during the bioconjugation reaction, which is also inspiring for reaction monitoring on SWCNTs.