A nanowire molecular sensor, and a molecular detection system, comprising a nanowire waveguide (30), a nanowire sidewall (51) functionalized in order to attach a molecule (54), and light emissive point sources (52), wherein the amount of light emitted at an end (53) of the waveguide is dependent of the amount of specific molecules attached to the sidewall of the nanowire. A method employing said sensor may be used for single cell detection and analysis.