Sensors and biosensors based on metal oxide nanomaterials

Nanomaterials have greatly boosted the biosensor field taking advantage of their optical, catalytic, magnetic and adsorption properties. While noble metal and carbon-based materials have been most often used, metal oxide nanomaterials (MONMs) have recently emerged as a useful platform for their high stability, low cost and versatility in chemical properties. In this article, we first introduce fundamental surface properties of MONMs, especially interactions with DNA. A few sensing strategies are then discussed including the modulation of the catalytic activities of MONMs, and competitive adsorption. DNA can serve as a signaling molecule, and a competitor to probe adsorption of other molecules by MONMs. In addition, DNA can also modulate the catalytic activity of MONMs. Such modulated activities were also observed by several small molecules or ions. In each case, related biosensor designs are introduced. Representative sensors using these mechanisms are reviewed and some future trends are discussed at the end.