Paper-based fluorescent immunoassay for highly sensitive and selective detection of norfloxacin in milk at picogram level.

Norfloxacin (NOR) in milk may influence mammalian cell replication and bring about a decrease in the efficiency for treating infection in humans. However, current techniques for detecting NOR usually require expensive instruments and trained personnel. In this work, we have developed a low-cost and simple method via paper-based fluorescent immunoassay for highly sensitive and selective detection of NOR in milk at picogram level. The NOR monoclonal antibody labeled with quantum dots is used as a detection probe to recognize the corresponding NOR, which can quantitatively detect NOR on paper-based devices. The detection limits in aqueous solution and milk are 1 pg/mL and 10 pg/mL, respectively. The developed paper-based method provides a cheap, sensitive, eco-friendly, and rapid approach for quantitative detection of trace NOR in milk, which may find wide applications in food safety inspection. Noteworthy, the method is especially suitable for applications at resource-limited and on-site settings.

Fixed eruption caused by ciprofloxacin without cross-sensitivity to norfloxacin.

We report the case of a female patient who presented fixed exanthema following administration of ciprofloxacin. To our knowledge, only one case of fixed exanthema in response to this agent has appeared in the literature, and it was associated with cross-sensitivity to norfloxacin.