Novel biomaterial based on monoamine oxidase-A and multi-walled carbon nanotubes for serotonin detection

In this study a novel biocomposite based on the enzyme monoamine oxidase-A (MAO-A) immobilized by covalent binding on multi-walled carbon nanotubes (MWCNT) has been developed for detection of serotonin. Immobilized MAO-A (MWCNT/MAO-A) retained 94.3 % of its catalytic activity, showing good thermal and pH stability at temperatures from 35 - 40 °C and pH from 7- 8.5. A decrease of the apparent Michaelis-Menten constant was observed compared to free MAO-A indicating an improvement of its affinity towards its substrate. Evaluation of MWCNT/MAO-A by scanning electrochemical microscopy (SECM) demonstrated that the immobilized enzyme maintains its activity. The biocomposite was employed for successfull detection of serotonin through quantification of the enzymatically produced hydrogen peroxide (H2O2). A MWCNT/MAOA modified glassy carbon electrode (GCE) was characterized by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Electrochemical measurements were performed in simulated body fluid (SBF), obtaining a linear response of 5.67 × 10-7 M - 2.26 × 10-6 M, with a low detection limit of 2 × 10-7 M (35.6 ng mL-1;S/N = 3) and a quantification limit of 6.73 × 10-7 M (118.7 ng mL-1;S/N = 3); values that are in range with serotonin levels found in different neurological disorders. The biocomposite have the potential to be employed in future development of biosensing devices for serotonin detection.Graphical abstract
Source: Biochemical Engineering Journal - Category: Biochemistry Source Type: research