Bead-based mesofluidic system for residue analysis of chloramphenicol

A highly selective and sensitive mesofluidic immunoassay system based on competitive immunoassay in polydimethylsiloxane (PDMS) channels was developed. This immunoassay system was successfully applied to quantificationally detect chloramphenicol (CAP) in animal foods. The glass beads (Ø 250 microm) were amino-silane modified, covalently precoated with chloramphenicol succinate, and then infused into the microchannels (Ø 300 microm); the CAP molecules of samples or standards in flow solution competed for CAP antibody with the CAP immobilized on the beads. The CAP antigen-antibody complex anchored on the beads was probed by Cy5-labeled secondary antibody, and the fluorescence intensities of beads were employed to determine the concentration of CAP. In this system, the detection limit of CAP is 0.008 microg/L. The method reveals good recovery rates from 90 to 108% and coefficients of variance (CV) from 4.72 to 6.52%. The experimental results demonstrate that the bead-based mesofluidic system has high sensitivity and excellent performance. Indeed, this system can readily be operated automatically and expanded for multicomponent analysis. It is therefore an attractive alternative to conventional immunoassays in routine supervised domain application for contamination in foods or the environment.