Gold nanoparticle-based paper sensor for ultrasensitive and multiple detection of 32 （fluoro）quinolones by one monoclonal antibody

For rapid and simultaneous detection of （fluoro）quinolones, a broadly specific monoclonal antibody （mAb） that recognizes 32 （fluoro）quinolone antibiotics was prepared using a mixture of a norfloxacin derivative and a sarfloxacin derivative as the hapten. An immunochromatographic strip based on gold nanoparticles （AuNPs） was then assembled with goat anti-mouse antibody and antigen （sarfloxacin coupled to ovalbumin）, used to form the C line and T line, respectively. This antigen competes with the （fluoro）quinolones in a sample incubated with mAbs labeled with AuNPs. The strip can detect 32 （fluoro）quinolones including oxolinic acid, nalidixic acid, miloxacin, pipemidic acid, piromidic acid, rosoxacin, cinoxacin, norfloxacin, pefloxacin, lomfloxacin, enofloxacin, fleroxacin, ciprofloxacin, enrofloxacin, dafloxacin, orbifloxacin, sparfloxacin, gemifloxacin, besifloxacin, balofloxacin, gatifloxacin, moxifloxacin, nadifloxacin, ofloxacin, marbofloxacin, flumequine, pazufloxacin, prulifloxacin, sarafloxacin, difloxacin, trovafloxacin, and tosufloxacin in milk within 10 min with the naked eye. The cut-off values of the strip range from 1 to 100 ng/mL and the limits of detection are 0.1- 10 ng/mL. The strip does not cross-react with antibiotics including tetracycline, sulfamethazine, ampicillin, erythromycin, aflatoxin B1, or gentamicin. In short, this immunochromatographic strip is a very useful tool for the primary screening of （fluoro）quinolones in milk.