An SPR biosensor for the detection of microcystins in drinking water
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A surface plasmon resonance (SPR) biosensor for the detection of microcystins (MCs) in drinking water has been developed. Several assay formats have been evaluated. The selected format is based on a competitive inhibition assay, in which microcystin-LR (MCLR) has been covalently immobilized onto the surface of an SPR chip functionalized with a self-assembled monolayer. The influence of several factors affecting sensor performance, such as the nature and concentration of the antibody, the composition of the carrier buffer, and the blocking and regeneration solutions, has been evaluated. The optimized SPR biosensor provides an IC50 0.67 ± 0.09 µg L−1, a detection limit of 73 ± 8 ng L−1, and a dynamic range from 0.2 to 2.0 µg L−1 for MCLR. Cross-reactivity to other related MCs, such as microcystin-RR (88%) and microcystin-YR (94%), has also been measured. The SPR biosensor can perform four simultaneous determinations in 60 min, and each SPR chip can be reused for at least 40 assay–regeneration cycles without significant binding capacity loss. The biosensor has been successfully applied to the direct analysis of MCLR in drinking water samples, below the provisional guideline value of 1 µg L−1 established by the World Health Organization for drinking water.
KeywordsMicrocystin-LR Label-free biosensor Self-assembled monolayer Surface plasmon resonance
This work has been funded by the Madrid Regional Government (ref. S-0505/AMB/0374), the ESF, the ERDF, the Spanish MEC (grant CTQ2006-15610-C02), Complutense University (GR58-08), by the Academy of Sciences of the Czech Republic (grant KAN200670701), and by the Ministry of Education, Youth and Sports (grant OC09058). Sonia Herranz thanks the Madrid Regional Government and the MEC for a doctoral and a travel grant, respectively.
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