Sensor for the detection of biomolecules

A sensor for detection of an analyte, comprising:

• a biocompatible sensing layer comprising a matrix, organic nanoparticles comprising an organic component and embedded in said matrix, and metal nanoparticles distributed within said matrix such that the organic nanoparticles do not contain metal nanoparticles and that the organic nanoparticles have molecules or chemical groups attached to surfaces thereof that bind to the analyte or have an enzymatic activity to detect the analyte,
• wherein said matrix is a polymer matrix or a polymer gel matrix, said organic nanoparticles include a light emitter and a sensitizer therein such that the organic nanoparticles emit light by photon up-conversion emission in the presence of said analyte and do not emit light by photon up-conversion emission in the absence of said analyte, and said metal nanoparticles are a metal material comprising at least one selected from the group consisting of Ag, Au, Co, Al, Cu, and a nitride of a transition metal.