Question

Rapid lateral flow assays based on the quantification of magnetic nanoparticle labels for multiplexed immunodetection of small molecules: application to the determination of drugs of abuse

Answer 1

A rapid lateral flow immunoassay is presented that uses carboxyl-modified superparamagnetic nanoparticles as labels that can be quantified by highly sensitive multi-channel electronic readers. The approach is generic in that it is likely to be applicable to numerous small molecules. The method permits both single- and multiplex assays at a point-of-need without sample pretreatment. It is user-friendly and offers attractive characteristics demonstrated here for detection of morphine, fentanyl and methamphetamine in . The competitive immunoassay uses commercially available reagents that do not require special permissions. After migration of sample, the lateral flow test strips are subjected to an alternating magnetic field at two frequencies. The response from the nanolabels is readout at a combinatorial frequency from the entire volume of a porous immunochromatographic membrane by the magnetic particle quantification technique.

application to the determination of drugs of abuse.

Estimating the detection time of a drug in urine is complex because of many different influencing factors and the lack of experimental data. Detection times vary depending on dose and route of administration, metabolism and characteristics of the screening and confirmation assays. Using a cut-off value of 1000 ng/mL, urinary samples can be positive for amphetamine for up to 5 days after intake of the drug.