(647e) Electrochemical Biosensor with Self-Assembled Peptide Nanotubes Encapsulated Horseradish Peroxidase

For enzyme biosensor synthesis, various materials and methods have been investigated to immobilize and stabilize enzymes. In this study, we have explored a new nanoscale template, peptide nanotubes (PNTs), in order to encapsulate the enzyme inside the PNTs for biosensor applications. PNTs are prepared by self-assembly of diphenylalanine (D-Phe-D-Phe) molecules to provide suitable nano-space for biomolecules. PNTs' well-ordered, chemically stable and biologically compatible properties are considered beneficial for enzyme encapsulation to enhance stability and selectivity of enzyme. The electrochemical biosensor for detecting hydrogen peroxide (H2O2) has been first developed using horseradish peroxidase (HRP) encapsulated in the self-assembled PNTs. Scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), atomic force microscopy (AFM), FT-IR, and X-ray diffraction (XRD) have been used to characterize the self-assembled PNTs. The electrode response characteristics of the sensor against H2O2 have been investigated using cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS). The influence of encapsulation of enzyme in PNTs has been investigated in terms of the enzyme activity of HRP and the mass transfer rate of analytes through the PNT capsules. When HRP was encapsulated in PNTs, the enzyme activity of HRP inside PNTs was increased as compared with that of the free HRPs in a solution and that of the immobilized HRPs on the Self-assembled monolayers (SAMs). The sensitivity, linear working range, the pH effect, the thermostability, response time, and long-term stability of the sensing system have been determined. The apparent Michaelis-Menten constant and the lower detection limit were also calculated. The PNT-based electrochemical biosensor showed promising results as an optimal template for bioelectronic devices and biosensors.