Development of a colorimetric inhibition assay for microcystin-LR detection: Comparison of the sensitivity of different protein phosphatases

The main drawback of this PP-based approach in solution is poor enzyme stabilisation. To overcome this problem, enzymes were entrapped within either a photopolymer or an agarose gel. PP2A from ZEU Immunotec and PP1 were immobilised at the bottom of microwells. The agarose-based tests performed better than the photopolymer-based assay for all of the enzymes. Therefore, the agarose gel is a good candidate to replace the photopolymer, which is generally used in PP-immobilising membranes. The assays based on enzyme-entrapping agarose gels showed detection limits equal to 0.17 μg L−1 and 0.29 μg L−1 with immobilised PP2A from ZEU and PP1, respectively. In view of these performances, these tests can potentially be used for monitoring water quality.