A novel chemiluminescent immunochromatographic assay strip for rapid detection of mercury ions

Abstract

Mercuric ions (Hg²⁺) have long been regarded as one of the most hazardous environmental pollutants with adverse effects on environmental safety and serious toxic effect on human health. In the present work, an anti-Hg²⁺ monoclonal antibody (anti-Hg²⁺ Mab) was prepared, which could directly recognize Hg²⁺ without the need for a chelator. This antibody was used to develop a chemiluminescent (CL) immunochromatographic assay strip (ICAS) for rapid, facile, specific and sensitive detection of Hg²⁺. A conjugate of ovalbumin and Hg²⁺ (OVA–Hg²⁺) adopted as a coating antigen was immobilized on a nitrocellulose membrane to assemble a test line of the developed ICAS. The anti-Hg²⁺ Mab was tagged with horseradish peroxidase (HRP) and deposited onto the conjugate pad of the ICAS to act as a signal tracer. After introduction of the sample solution containing Hg²⁺, the immobilized OVA–Hg²⁺ conjugate competed with Hg²⁺ in the sample solution to bind with HRP-tagged anti-Hg²⁺ Mab. Afterward, a CL reaction signal catalyzed by the bound HRP was collected to quantitate the level of Hg²⁺ in the sample solution. Under optimal conditions, the linear range for Hg²⁺ detection was 1.0–100 ng mL⁻¹, with a detection limit of 0.2 ng mL⁻¹ (S/N = 3). The whole detection procedure could be accomplished within 18 min. The recovery values of Salvia Miltiorrhiza and lake water samples spiked with Hg²⁺ were 94.5–114.8% and 88.0–90.0%, respectively, showing acceptable reliability for real sample detection.