Contaminant detection in treated water using Optiqua's MiniLab (TM) biosensing system: a case study for Bisphenol A

摘要

An inhibition assay for detection of Bisphenol A (BPA) in treated water has been developed and validated for the MiniLab (TM) system from Optiqua Technologies. This biosensor-based analytical system can be used for detection of specific contaminants in solution. The system uses an integrated optic Mach-Zehnder interferometer chip that is functionalised with a biochemical interface layer. The sensor chip surface was first coated with aminodextran which formed a hydrophilic layer suitable for further modification. 4,4-bis(4-hydroxyphenyl) valeric acid (BVA), which is a structural analogue of BPA, was then successfully coupled to the aminodextran layer. This surface chemistry was used in a qualitative inhibition assay format for the selective detection of the presence of BPA. The assay was developed and optimised using a polyclonal anti-BPA antibody. Samples from 12 different water matrices of Singapore were spiked with known amounts of BPA and tested with the MiniLab (TM) system. The working range of the BPA inhibition assay is from 0.5 to 5 mu g/L. Intra- and inter-assay variations were measured, with calculated relative standard deviation averaging of about 15%. BPA concentrations of the spiked samples were also verified and confirmed with LC-MS. Such functionalised biosensor chip can be reused for more than 200 sample injections over a period longer than 6months. Developed as a robust, user-friendly and cost-effective system that can be field deployed, the MiniLab (TM) system enables target-specific assays currently only available in the lab to become available in the field.