Ultra-sensitive detection of AFP based on multi-spectral information from face-to-face aggregation of gold triangular nanoplates

A spectrum sensing method based on the localized surface plasmon resonance (LSPR) of colloidal gold triangular nanoplates has been investigated for detection of alpha-fetoprotein (AFP). Because of the AFP induced face-to-face aggregation of the nanoplates, both the absorbance intensity and the peak wavelength of the in-plane dipole plasmon resonance are sensitive to the AFP concentration. By analyzing the intensity decrease and blue shift of the absorption peak, AFP could be detected with an ultra low detection limit of 0.2 pg/mL. By taking the product of peak wavelength and intensity as the new detecting parameter, the sensing capacity could be further improved, which presents a new sensing picture based on tuning the multi-spectral information.