Development of a nanobody-based immunoassay for the analysis of the disinfectant triclosan in water.

Triclosan (TCS), a broad-spectrum antimicrobial agent in pharmaceuticals and personal care products, necessitates environmental monitoring due to its antimicrobial properties and widespread in the environment. In this study, two anti-TCS single-domain antibodies (i.e., nanobodies, Nbs), T1 and T2, were isolated from a phage-displayed Nb library derived from a camel immunized with a mixture of TCS immunogens. The T1-based enzyme-linked immunosorbent assay (ELISA) exhibited a better sensitivity to TCS than the T2-base ELISA. Motivation at enhancing specificity, sensitivity, and stability of Nb-based immunoassays promoted exploring use of a bivalent strategy to enhance performance. The bivalent Nb T1-T1 was tandemized via a linker-(GGGGS)3- between. The thermal stability of the bivalent Nb was improved in comparison with that of a monovalent Nb. The sensitivity of T1-T1-based ELISA, with an IC value of 4.3 ng mL of TCS, was improved approximately 2-3 fold in comparison to those of T1-or T2-based ELISAs (8.5 and 14.6 ng mL, respectively). The average recovery of TCS from water samples measured with T1-T1-based ELISA was in the range of 99-125 %, which correlated well with that measured by a high-performance liquid chromatography (HPLC) method (R > 0.99). TCS in river water samples was detected by the resultant ELISA and an HPLC method, showing a satisfactory correlation.