A novel glucose biosensor using bi-enzyme incorporated with peptide nanotubes

A novel amperometric glucose biosensor was developed using the bio-inspired peptide nanotube (PNT) as an encapsulation template for enzymes. Horseradish peroxidase (HRP) was encapsulated by the PNT and glucose oxidase (GOx) was co-immobilized with the PNT on a gold nanoparticle (AuNP)-modified electrode. A binary SAM of 3-mercaptopropionic acid (MPA) and 1-tetradecanethiol (TDT) was formed on the surface of the electrode to immobilize the PNT and GOx. The resulting electrode appeared to provide the enzymes with a biocompatible nanoenvironment as it sustained the enhanced enzyme activity for an extended time and promoted possible direct electron transfer through the PNT to the electrode. Performance of the biosensor was evaluated in terms of its detection limit, sensitivity, pH, response time, selectivity, reproducibility, and stability in a lab setting. In addition the sensor was tested for real samples. The composite of AuNP-SAM-PNT/HRP-GOx to fabricate a sensor electrode in this study exhibited a linear response with glucose in the concentration range of 0.5−2.4 mM with a R2-value of 0.994. A maximum sensitivity of 0.3 mA M−1and reproducibility (RSD) of 1.95% were demonstrated. The PNT-encapsulated enzyme showed its retention of >85% of the initial current response after one month of storage.

► Peptide nanotubes were used to encapsulate enzymes. ► Bi-enzyme system was used to detect glucose. ► AuNP-SAM modified gold electrodes were used. ► PNT-encapsulation maintained enzyme activity for an extended time. ► The new system showed good reproducibility and stability.