Abstract

A novel dual-site recognition protocol was developed for chemiluminescent (CL) detection of Streptococcus mutans (S. mutans) based on a designed antibiotic-affinity strategy. Teicoplanin, a broad-spectrum antibiotic against Gram-positive bacteria, was adopted to functionalize magnetic particles and recognize S. mutans utilizing the strong affinity between this agent and D-Alanyl-D-Alanine peptide moieties in the bacterial cell wall. To achieve ideal specificity for S. mutans detection, rat immunoglobulin G2a (rat IgG2a) tagged with horseradish peroxidase (HRP) was used as the second recognition agent and signal tracer since Fab region of rat IgG2a could bind with streptococcal protein G highly expressed in the cell wall of S. mutans. Thus HRP-tagged sandwich complex of teicoplanin/S. mutans/rat IgG2a was formed on the magnetic particles, followed by a CL quantification of S. mutans based on a HRP-catalyzed luminol-H2O2-p-iodophenol CL reaction. This dual-site recognition protocol showed a linear range of 1.0 × 102–1.0 × 106 CFU mL−1 and a detection limit of 33 CFU mL−1 for S. mutans detection. The whole detection process could be completed within 70min. The recovery tests for food, environmental, pharmaceutical and biological samples showed acceptable recovery values between 83.0% and 110.0%, demonstrating its application potential for detection of bacteria in various sample matrixes.

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