Used in the development of biosensors and diagnostic assays due to its ability to undergo topochemical polymerization upon UV irradiation, forming a stable polydiacetylene matrix. This polymerization results in a visible color change from blue to red, which can be used as a colorimetric indicator for detecting biological interactions such as membrane binding, viral detection, or ligand-receptor binding. Frequently incorporated into liposome-based systems or thin films for rapid, label-free detection of pathogens, toxins, or cellular components. Its conjugated backbone provides optical sensitivity, making it valuable in smart materials and responsive coatings.