Cyanobacterial toxin biosensors for environmental monitoring and protection

Cyanobacterial toxins are primarily monitored using a variety of commercially available techniques,such as enzyme-linked immunosorbent assay(ELISA)and liquid chromatography–mass spectrometry(LC-MS).Indeed,official protocols created and utilized by regulatory bodies have these methodologies ingrained into the technical documentation.However,biosensor technology has been advancing for decades and are positioned to replace many existing methods.The requirements of biosensors include,but are not limited to,real time diagnostics,ease of use(reducing requirements for trained personnel),lower costs,high sensitivity,robust platforms,and good reproducibility.In contrast,laboratory techniques like ELISA require immobile equipment and the use of certified standards for toxin quantification.The use of biosensors may reduce the overall burden of materials and associated costs of production.Given the regulatory limits for toxins in drinking water and recreation,a wide array of biosensor platforms(graphene-based,optical,immunological,etc.)reported in the literature have sufficient sensitivity to comply with these guidelines,however,currently no biosensor has been approved for use in the same manner or accepted as a suitable alternative.In many cases,biosensors have been compared in a limited capacity to established technologies such as the previously mentioned ELISA,LC-MS,and HPLC(High Performance Liquid Chromatography)and would serve as good tools to be used as proxy screening methods.Biosensors examined in this review are evaluated on four criterion:(1)feasibility for point-of-care(POC)use,(2)assay time(time from sample collection to receipt of data),(3)variation between measurements(reported coefficient of variation values),and(4)dynamic range and/or limit of detection(LOD)to obtain a measure of a given technique’s suitability to be used for toxin quantification and detection.