Direct colorimetric study on the interaction of Escherichia coli with mannose in polydiacetylene Langmuir-Blodgett films

The membranes of polydiacetylene backbone decorated with mannose assembled by Langmuir-Blodgett technology can interact with Escherichia coli. The interactions lead to the color transition of the membranes which was readily visible to the naked eyes and could be quantified by visible absorption spectroscopy. To understand the mechanism of the chromatic transition, the affinochromism properties of polydiacetylene were examined by resonance Raman spectroscopy. The results demonstrated that the side chains of polymer backbone performed rearrangement, and the electronic structure in the polymer backbone changed from acetylene to butatriene form when the chromatic transformation from blue to red. The direct colorimetric detection by polydiacetylene membranes not only opens a new path for the use of these membranes in the area of biosensor development but also offers new possibilities for diagnostic applications and screening for binding ligand. (C) 2002 Elsevier Science B.V. All rights reserved.