Polydiacetylenes are a class of polymers
with unique optical properties.
Upon photopolymerization, monomers form a deep blue, nonfluorescent
polymer, which transitions to a red, fluorescent polymer in response
to various environmental factors such as pH, temperature, or molecular
binding. The chromatic and emissive properties of polydiacetylenes
have generated considerable popularity for their use in biosensing
applications over the past three decades. The versatility of polydiacetylene
forms has also allowed for a wide range of sensors including liposome
bacterial sensors, films for detecting influenza virus, hydrogels
for protein detection, and printed ink for the detection of volatile
organic compounds. In this article, we review the wide range of techniques
employed in the development of polydiacetylene sensors and summarize
methods to modify, characterize, and analyze polydiacetylene-based
sensing systems. Additionally, we discuss the recent directions of
polydiacetylene materials outside of sensing applications as versatile
tools in biomedicine and tissue engineering.