A MINIATURE SURFACE PLASMON RESONANCE BIOANALYTICAL SYSTEM FOR FIELD DETECTION OF MICROCYSTIN-LR IN SURFACE WATER

A miniature surface plasmon resonance (SPR)-based immunoassay system for analyzing microcystin-LR (MC-LR) in surface water has been developed. A Spreeta biosensor was adopted in the SPR flow injection analysis (FIA) system. An optional biofilm immobilization method was exploited using covalent-coupling between a bioconjugate of microcystin-LR and bovine serum albumin [(MC-LR)-BSA] and the golden surface. An acceptable relative standard deviation of repeatability, 1.29% (n = 20), was achieved. An analysis of the calibration curve showed that this method has a detection limit of 0.55 ng/mL, a half-maximal inhibitory concentration (IC50) of 5.6 ng/mL, and a quantitative range of 1.56-25.00 ng/mL. The recovery from water samples containing varying concentrations of MC-LR ranged from 90% to 112%. After samples of tap water and pool water were assayed, it was concluded that tap water did not contain a measurable amount of the analyte, whereas pool water contained 2.39 ng/mL. Compared to other methods of analysis, SPR immunoassay has the advantage of being label-free, rapid, and cost-effective and can easily detect levels of MC-LR within the World Health Organization (WHO) drinking water guidelines. The SPR FIA system with reusable biosensor is compact and convenient for instant in situ determination of MC-LR levels in environmental water.