Low level detection of microcystin using a plasmonic biosensor

The presence of cyanobacterial blooms in fresh water has increased due to the accelerated eutrophication of surface water sources. Catastrophic impact to local human and wildlife ecosystems from blooms is linked to the release of hepatotoxins, such as microcystins, into fresh water sources. Therefore, a low-cost, reliable, and highly sensitive method for low concentration detection of microcystins is vitally important to minimize public health risks. In this paper, we report on the first experimental demonstration of microcystins-LR (MC-LR) at low part-per-trillion levels. The demonstrated sensor uses periodically coupled artificial nanostructures to excite a highly sensitive electromagnetic surface wave which directly probes interactions between immobilized antibodies and MC-LR. A layer-by-layer polyelectrolyte adsorption process is utilized to provide highly stable and site-directed immobilization of target antibodies. Steady-state response of the fabricated biosensor confirms detection of MC-LR antigens at low part-per-trillion concentration levels. This demonstration is an important first step towards the development of a lab-on-a-chip sensing systems for in-situ, real-time, distributed environmental monitoring of MC-LR levels in drinking water.