Signal Generation from Switchable Polydiacetylene Fluorescence

Abstract

AbstractChemical and biological sensors require a material component to act as a transducer from the molecular level event of interest to a discernable output measurable in the macroscopic world. One such material is polydiacetylene (PDA), a conjugated polymer that can switch from harnessed to provide signal generation for bio-sensors and assays as a more sensitive alternative to the previously reported monitoring of PDA colorimetric shifts. While providing a more sensitive transduction mechanism the fluorescence behavior of PDA is also more complicated than the absorbance, in particular the emission profile of PDA in liposomes is strongly affected by the extent of polymerization. Incorporating small molecule fluorophores into the PDA materials further increases the overall emission of fluorescent PDA materials. The fluorophores accept energy from the excited state of the polymer and fluoresce, leading to both an overall increase in the quantum yield of the system and an increase in the Stokes shift. Basic photophysical properties of fatty acid PDA liposomes and a model assay for phospholipase A2 are presented. The model assay results show that the fluorescence response is greater than the colorimetric, and is further enhanced by addition of fluorophores.