title: Next generation planar waveguide detection of microcystins in freshwater and cyanobacterial extracts, utilising a novel lysis method for portable sample preparation and analysis.
abstract: 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 10 min. 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 0.78 ng mL(-1) and the CCβ to be 1 ng mL(-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 (R(2)=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 1 ng mL(-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 0.1 ng mL(-1). This allows the determination of microcystins at and below the World Health Organisation (WHO) guideline value of 1 μg L(-1). This sensor represents a major advancement in portable analysis capabilities and has the potential for numerous other applications.
authors.affiliation: Institute for Global Food Security, School of Biological Sciences, Queen's University, Malone Road, 18-30 Belfast, BT9 5BN, Northern Ireland, United Kingdom. s.devlin@qub.ac.uk
authors.forename: Shauna
authors.initials: S
authors.lastname: Devlin
authors.forename: Julie P
authors.initials: JP
authors.lastname: Meneely
authors.forename: Brett
authors.initials: B
authors.lastname: Greer
authors.forename: Charles
authors.initials: C
authors.lastname: Greef
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Lochhead
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Elliott
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology; D002851:Chromatography, High Pressure Liquid; D000458:Cyanobacteria / Q000378:metabolism*; D005618:Fresh Water / Q000032:analysis*; D007118:Immunoassay; D052998:Microcystins / Q000032:analysis* / Q000276:immunology; D046931:Microcystis / Q000254:growth & development / Q000378:metabolism; D053719:Tandem Mass Spectrometry
chemical_list: D000911:Antibodies, Monoclonal; D052998:Microcystins; C078588:microcystin