Nanoparticles with electrochemical properties such as red-ox changes easy to be followed by stripping analysis or electrocatalysis to be followed by simple amperometric detection represent interesting building blocks in the design and fabrication of novel biosensors with interest for diagnostics applications. Various examples related to DNA, protein and cell detection are shown. Nanoparticles are mostly used as labels in a similar way as enzymes or dyes but offering the advantages of better stability and in general cost efficiency of the devices. The employment of nanoparticles in electrochemical based biosensing systems is simple and the obtained performance seems to fit with the requirements for real applications in detection of various biomarkers with interest for point of care applications and even early detection or during treatment of illnesses such as cancer, beside others.