Development of an eco-friendly immunochromatographic test strip and its application in detecting Hg2+ without chelators

Abstract

Here, a specific anti-Hg²⁺ monoclonal antibody (mAb) was generated and an eco-friendly immunochromatographic test strip (EFITS) based on a mAb-nanogold probe for rapid and specific detection of Hg²⁺ in water was developed. In the method, the conjugation of Hg–MNA (6-mercaptonicotinic acid)–BSA (bovine serum albumin) was synthesized as an immunogen, the conjugation of MNA–OVA (ovalbumin) was synthesized and selected as a coating antigen. The specific anti-Hg²⁺ mAb from BALB/C female mice was screened based on a competitive immunoassay. The coating antigen and goat anti-mouse IgG antibody were coated on a nitrocellulose membrane (NC membrane) as a test line and a control line, respectively. The anti-Hg²⁺ mAb-nanogold probe was applied to the conjugate pad. Hg²⁺ competes with OVA–MNA for the mAb-nanogold probe causing a color change on the test line corresponding to the Hg²⁺ content. Thus, we can distinguish the subtle differences through a strip reader. The resulting EFITS is able to detect Hg²⁺ with LOD of 0.4 ng mL⁻¹ at 9 min by quantitative analysis. EFITS demonstrated here is eco-friendly (without Hg²⁺ on the strip), capable of rapid detection, and does not require chelators.