Dual Immunomagnetic Nanobeads-Based Lateral Flow Test Strip for Simultaneous Quantitative Detection of Carcinoembryonic Antigen and Neuron Specific Enolase

A novel immunomagnetic nanobeads -based lateral flow test strip was developed for the simultaneous quantitative detection of neuron specific enolase (NSE) and carcinoembryonic antigen (CEA), which are sensitive and specific in the clinical diagnosis of small cell lung cancer. Using this nanoscale method, high saturation magnetization, carboxyl-modified magnetic nanobeads were successfully synthesized. To obtain the immunomagnetic probes, a covalent bioconjugation of the magnetic nanobeads with the antibody of NSE and CEA was carried out. The detection area contained test line 1 and test line 2 which captured the immune complexes sensitively and formed sandwich complexes. In this assay, cross-reactivity results were negative and both NSE and CEA were detected simultaneously with no obvious influence on each other. The magnetic signal intensity of the nitrocellulose membrane was measured by a magnetic assay reader. For quantitative analysis, the calculated limit of detection was 0.094 ng/mL for NSE and 0.045 ng/mL for CEA. One hundred thirty clinical samples were used to validate the test strip which exhibited high sensitivity and specificity. This dual lateral flow test strip not only provided an easy, rapid, simultaneous quantitative detection strategy for NSE and CEA, but may also be valuable in automated and portable diagnostic applications.