Complete antigen-bridged DNA strand displacement amplification immuno-PCR assay for ultrasensitive detection of salbutamol

Monitoring of low-level analytes are typical examples for analytical challenges. Salbutamol (SAL), a phenol-beta(2)-agonist, has a very low residual content in the environment. Here, we present an ultrasensitive complete antigen-bridged PCR assay for detecting salbutamol (SAL). These DNA probes modified SAL complete antigens target recognition SAL antibodies and agglutinate syntheticDNA conjugates, thus enabling ligation of DNA probes to form a full-length DNA amplicon that contained a recognition site for cleavage endonuclease and subsequent quantification by qPCR. Moreover, SAL antibodiesweremodified with magnetic beadswhichwere used to reduce the background noise and sample matrix effect, and the DNA signals were isothermally amplified by strand displacement amplification technology. Some key parameters which influence assay performance were optimized: the length of the bridge oligonucleotide, the concentration of immunomagnetic beads, SAL probes, and initiation chain, etc. Under the optimumconditions, the signal amplification of proposed Immuno-PCR assay for the detection of SAL was exponential, resulting in high potential sensitivity(similar to 1 fg/mL) and a broad detection dynamic range (> 10(5) fold). Using this proposedmethod, we detected SAL in spiked tap water and urine samples with acceptable recoveries ranging from 88.1 to 103.3%. Theoretically, themethod developed here has broad applicability and practical utility in immunoassays of a wide variety of analytes. (c) 2020 Published by Elsevier B.V.