Polydiacetylene-containing solid colorimetric and/or fluorescent detector, method for its preparation and uses thereof

The invention provides a colorimetric and/or fluorescent detector, which is a solid organic matrix, most preferably in the form of a gel, comprising polydiacetylene(s) and one or more lipids. Processes for preparing the detector and methods for using the same, including for the detection of microorganism suspected to be present in food products, are also provided.