Next generation planar waveguide detection of microcystins in freshwater and cyanobacterial extracts, utilising a novel lysis method for portable sample preparation and analysis

• Published in: Analytica chimica acta 2013-03, Vol.769, p.108-113
• Main Authors: Devlin, Shauna, Meneely, Julie P., Greer, Brett, Greef, Charles, Lochhead, Michael J., Elliott, Christopher T.
• Format: Article
• Language: English
• Subjects: Antibodies, Monoclonal - immunology; Assaying; Beads; Blue-green algae; Chromatography, High Pressure Liquid; Cyanobacteria; Cyanobacteria - metabolism; Evanescent waves; Fresh Water - analysis; Freshwaters; Immunoassay; Mathematical analysis; Microcystin; Microcystins - analysis; Microcystins - immunology; Microcystis - growth & development; Microcystis - metabolism; Novel lysis; Planar waveguide; Planar waveguides; Portability; Portable biosensor; Sensors; Tandem Mass Spectrometry
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2013.01.033

[Display omitted] ► Sensitive assay for the detection of the most common and toxic microcystin variants. ► Detection of free and cell bound microcystin for a true reflection of toxin content. ► Novel, highly effective lysis method enabling fast and portable disruption of cells. ► Validated to measure microcystins below 1 and 0.1ngmL−1; free and intracellular. ► Next generation planar waveguide biosensor combining quantification and ease of use. The study details the development of a fully validated, rapid and portable sensor based method for the on-site analysis of microcystins in freshwater samples. The process employs a novel lysis method for the mechanical lysis of cyanobacterial cells, with glass beads and a handheld frother in only 10min. The assay utilises an innovative planar waveguide device that, via an evanescent wave excites fluorescent probes, for amplification of signal in a competitive immunoassay, using an anti-microcystin monoclonal with cross-reactivity against the most common, and toxic variants. Validation of the assay showed the limit of detection (LOD) to be 0.78ngmL−1 and the CCβ to be 1ngmL−1. Robustness of the assay was demonstrated by intra- and inter-assay testing. Intra-assay analysis had % C.V.s between 8 and 26% and recoveries between 73 and 101%, with inter-assay analysis demonstrating % C.V.s between 5 and 14% and recoveries between 78 and 91%. Comparison with LC–MS/MS showed a high correlation (R2=0.9954) between the calculated concentrations of 5 different Microcystis aeruginosa cultures for total microcystin content. Total microcystin content was ascertained by the individual measurement of free and cell-bound microcystins. Free microcystins can be measured to 1ngmL−1, and with a 10-fold concentration step in the intracellular microcystin protocol (which brings the sample within the range of the calibration curve), intracellular pools may be determined to 0.1ngmL−1. This allows the determination of microcystins at and below the World Health Organisation (WHO) guideline value of 1μgL−1. This sensor represents a major advancement in portable analysis capabilities and has the potential for numerous other applications.