A dry chemistry, ultrasensitive microfluidic fiber material-based immunosensor for electrochemiluminescence point-of-care testing of luteinizing hormone

Luteinizing hormone (LH) is a gonadotropin, and its concentration is closely related to the female ovulation cycle. However, the traditional lateral flow method for LH detection has poor sensitivity and sustainability. In this work, a dry chemistry, ultrasensitive microfluidic fiber material-based immunosensor (μFIS) has been firstly proposed for electrochemiluminescence (ECL) point-of-care testing (POCT) of LH. The μFIS was composed of four-layer fiber material (paper and cloth)-based pads, and was combined with closed bipolar electrode-ECL (CBPE-ECL) to quantitatively detect LH. The CBPE-ECL μFIS not only retained the high sensitivity and wide linear range associated with CBPE-ECL, but also reserved the simplicity and practicality of the lateral flow assay. In addition, a self-enhanced intramolecular ECL probe was incorporated into the μFIS for signal amplification. Under optimized conditions, the μFIS had a very low detection limit (0.125 μIU mL-1) and positive linear relationship (0.001–100 mIU mL-1), together with excellent selectivity, reproducibility and storage stability. Moreover, the CBPE-ECL μFIS was applied to detect LH in human clinical serum samples, and the results had a good correlation with those of clinical samples. These results revealed that the CBPE-CEL μFIS had the potential as a high-performance POCT for LH or other biomarkers.