Broad-Specificity Immunochromatographic Strip Assay for Alkaloids: From Hapten Design to Antibody Recognition

Although alkaloids are physiologically active, their toxic effects on organ systems and genetic toxicity risks cannot be ignored, necessitating rapid and simultaneous detection of these hazardous compounds. Using tetrahydro-1H-pyrrolizine-7a(5H)-acetic acid hydrochloride as the hapten, we developed a group-specific monoclonal antibody (mAb 1B6) capable of simultaneously recognizing nine alkaloids (senecionine, retrorsine, seneciphylline, monocrotaline, usaramine, atropine, l-hyoscyamine, scopolamine, and physostigmine). The three-dimensional structure of mAb 1B6 was successfully constructed by homology modeling to study the antibody recognition mechanism. Based on this antibody, a gold nanoparticle-based immunochromatographic strip (AuNP-ICS) was established for detecting these alkaloids in wheat, with visual detection limits of 100-1000 μg/kg and calculated detection limits of 5.84-100.53 μg/kg. Spiked recovery experiments confirmed that the method was accurate and stable, and yielded recovery rates of 95.39%-105.76% and coefficients of variation of 1.02%-3.22%, consistent with LC-MS/MS results. Therefore, this AuNP-ICS represents a practical tool for rapidly detecting alkaloids in wheat.