Cerium Oxide Nanoparticles Decorated SAM Modified Gold Electrode for ROS Biosensing

Informatics is a new and flourishing sector in biomedical engineering with biosensors playing a crucial, central role. Self-Assembled monolayer (SAM) based biosensors constitute a large portion of these due to their simplistic design and broad application. Herein we present a cerium oxide nanoparticle (CNPs) functionalized SAM biosensor for amperometric reactive oxygen species (ROS) detection. SAM-based biosensors often times employ enzymes to detect analytes. These sensors are limited to particular pH, salt concentration, and temperature conditions specific to normal conditions for the enzyme. Operation outside these conditions can cause irreversible protein denature and loss of sensation. It is well established that CNPs has unique oxidase like activity.[1, 2] Therefore, by using inorganic CNPs, this sensor is able to operate at adverse conditions without loss of sensitivity. The inorganic material also prevents phase interactions which could result in bio-fouling. The presented sensor is able to detect extremely low concentrations for H2O2 and with high selectivity. Bare gold electrode was used as a substrate and coated with an SAM of mercaptododecanoic acid (MDDA), a well-established SAM polymer. The carboxylic terminus of MDDA was used for CNPs conjugation. Cyclic voltammetry and chronoamperometric testing was performed in phosphate-buffered saline and potassium hexacyanoferrate, a well-known redox couple. Hydrogen peroxide was infused in micromolar concentrations for sensing. Comparison to bare gold electrodes shows orders of magnitude greater sensitivity to [H2O2] and significantly more defined analyte selectivity.

References:

1. Hirst, S.M., et al., Anti inflammatory Properties of Cerium Oxide Nanoparticles. Small, 2009. 5(24): p. 2848-2856.
2. Gaynor, J.D., et al., Enzyme-free Detection of Hydrogen Peroxide from Cerium Oxide Nanoparticles Immobilized on Poly (4-vinylpyridine) Self–Assembled Monolayers. J. Mater. Chem. B, 2013.