Polydiacetylene (PDA) materials are used as a platform for detection of biological analytes such as microorganisms, viruses and proteins. The environmentally responsive chromic and emissive properties of the polymer, combined with self-assembled material formats, make these materials particularly attractive for biosensing applications. A variety of approaches have been used in developing these materials and demonstrating their potential for biological detection. In this feature article we describe different PDA material formats, discuss the optical properties that are the basis for signal generation, and review the use of PDA for biosensing.

An efficient and versatile synthesis of a series of polymerizable amphiphilic mesogens that affords control over tail length and position of the polymerizable group is described. The synthesis employs a novel and facile method of preparing styrene ethers. The monomers are sodium salts of styrene ether-modified fatty acids that can be used to form cross-linkable inverted hexagonal (H II ) lyotropic liquid crystal (LLC) phases at ambient temperature with controllable nanometer-scale dimensions. Examination of a series of regioisomers with the same alkyl chain length but with the styrene ether group at different locations along the chain revealed that the position of the styrene ether has a profound effect on the dimensions of the resulting H II phase at a fixed temperature and composition. Increasing overall monomer tail length also has a significant, although smaller, effect on the unit cell dimensions of the LLC phase. By controlling the structure of the LLC monomer in this manner, cross-linked H II phases with interchannel distances (ICD) ranging from 29 to 54 Å can be obtained. Furthermore, changing the counterion from Na + to tetraalkylammonium ions leads to further expansion of the H II unit cell to a maximum ICD of 65 Å, as well as to the production of a lamellar phase. Use of these monomers affords a new and unparalleled degree of control over phase structure and dimensions for the production of nanostructured organic materials.

The preparation and characterization of coatings made from polydiacetylene colloids on nano- and microporous membranes and their potential for the detection of microorganisms are presented.