Development of an intelligent polymerized crystalline colloidal array colorimetric reagent

We have developed a novel colorimetric reagent for the determination of Pb2 +, pH, and temperature. This colorimetric reagent consists of a dispersion of similar to 100-mum particles composed of an intelligent polymerized crys talline colloidal array (IPCCA). The IPCCA particles are composed of a hydr ogel polymerized around a face-centered cubic (fcc) array of monodisperse, highly charged polystyrene colloidal particles. These IPCCA particles diffr act visible light because the (111) planes of the fcc polystyrene colloidal particle array have an similar to 200-nm lattice constant. The IPCCA parti cles also contain a molecular recognition agent that actuates array volume changes as a result of changes in analyte concentration or temperature. Thi s results in changes in the IPCCA lattice constants, which shifts the wavel ength of fight diffracted. We report here the use of these sensing material s in a liquid dispersion that can be poured into a sample solution. This di ffraction measurement method is analogous to X-ray powder diffraction measu rements. The diffraction wavelength is monitored at a defined angle relativ e to the incident light.