In vitro diagnostic assay methods

An in vitro diagnostic assay method, comprising:

• providing a sample which may comprise target analyte(s);
• contacting the sample with a fluorescent label whose fluorescence can be externally modulated, such that the fluorescent label is associated with target analyte(s), if present, to form a fluorescent label-analyte complex;
• and
• detecting the fluorescent label-analyte complex;
• wherein said fluorescent label is a material which contains a nitrogen vacancy center;
• wherein the method further comprises:
• a) exciting the fluorescent label using a suitable light source, and detecting the resulting fluorescence;
• b) modulating the fluorescence of the fluorescent label and detecting the resulting fluorescence to obtain a fluorescence time series comprising the fluorescence results from steps a) and b);
• and
• c) optionally repeating the modulation step one or more times and detecting the resulting fluorescence to obtain a fluorescence time series comprising the fluorescence results from steps a), b) and c);
• and
• wherein the sample is applied to a solid phase comprising a multiwell plate, beads, column, photonic device, microfluidic chip or capillary bed for microfluidic flow assay;
• further wherein the assay method comprises a microfluidic flow assay, ELISA, gPCR, microarray, isothermal amplification, dot-blot, flow cytometry, fluorescence-activated cell sorting (FACS), a lateral flow assay or a vertical flow assay.