IN A NUTSHELL: Polydiacetylenes (PDAs) are typically known as highly colored materials that shift in color and absorbance when subjected to external physical stresses such as changes in temperature, pH, pressure, solvent, or molecular recognition event. Under the right conditions the color change can be reversible. Polymerization is typically initiated by exposure to ultraviolet light or gamma radiation. Diacetylene monomer functionality must be preorganized in close physical proximity in order for polymerization to take place. Pioneering work by Charych and coworkers in the early 1990’s demonstrated the utility of polydiactylene materials in chemical and biological sensing applications. The problem with these materials is that their compositions must be limited to physical structures that enforce the preorganization needed for polymerization. Also, the diacetylene functional groups tend to be very hydrophobic. Their often crystalline morphology can make processing into coatings impractical. Typically, processing compositions such as Langmuir-Blodgett films, self assembled monolayers and vesicles have been used to achieve the needed geometries, and as convenient platforms for sensor construction. PAMAM dendrimers offer an alternative approach towards meeting the structural demands for diacetylene polymerization due to their multiple, close packed end-groups situated at the periphery. Covalent bonding of diacetylene monomers to the periphery of the PAMAM dendrimer brings them into the alignment needed for polymerization due to their geometrical proximity, and the tendency of the resulting amphiphilic dendritic construct to self-aggregate. The intrinsically hydrophilic composition of PAMAMs is also an advantage for biosensor applications. Finally, their typically amorphous properties are well suited for coating fabrication.

BENEFITS Colorimetric polydiacetylene sensing material that can be conveniently applied to a variety of substrates has been developed. Low crystallinity has been advantageously achieved. Large number of available functional end-groups on dendrimer surface can advantageously produce high sensitivity.

STAGE OF DEVELOPMENT Feasibility has been demonstrated with the avidin-biotin interaction.

NEXT STEPS Seeking to license for sensing applications.