Photonic crystal nanolaser is an easily fabricated and operated semiconductor laser, which can be a high performance biosensor chip. It detects not only the environmental index of adsorbed bio-molecules as the laser wavelength shift but also the surface charge as the change in the emission intensity. This capability allows the simultaneous analysis of optical and electrical properties of target bio-molecules. Such multi-sensing is demonstrated for hybridization of DNAs. This nanolaser also shows ultrahigh sensitivity for antibody-antigen reactions of biomarker proteins and ultrahigh selectivity against contaminants, which are promising to medical diagnoses.
For example, PSA for prostatic cancer is detected from 1 fM even with 10 µM contaminants, and CRMP2 for Alzheimer disease is detected from 10 pM in animal-derived sample. It is also applicable to detecting endotoxin, the environmental toxin, which must be removed in clinical treatments. A low concentration of 0.001 EU/ml is detected within 33 min by monitoring limulus amebocyte lysate reaction with endotoxin.