Label-free surface plasmon resonance cytosensor for breast cancer cell detection based on nano-conjugation of monodisperse magnetic nanoparticle and folic acid

Accurate diagnosis of breast cancer cells is important on determining the stage of the disease and designing the suitable therapies. Herein, we report a sensitive biosensor based on surface plasmon resonance (SPR) spectroscopy using magnetic nanoparticle (MNP) and a two-marker recognition system. While the target breast cancer cells (MCF-7) are captured by MUC1 aptamer on the surface selectively, folic acid conjugated monodisperse MNP is used as the second selective binding reagent to form a sandwich SPR assay. The signal of SPR was enhanced significantly. This enhancement was mainly attributed by the larger mass and higher refractive index of the MNP nanoparticles located in the evanescent field. The detection limit can be achieved as low as 500 cells mL−1. This work may afford a new model to improve the sensitivity and selectivity of SPR biosensors for large-size analytes.