Polyelectrolyte self-assembled thin films containing cyclo-tetrachromotropylene for chemical and bio-sensing

Thin composite films containing cyclo-tetrachromotropylene (Chromol) were d eposited onto glass slides by means of polyelectrolyte self-assembly techni que. The films obtained were characterised by UV-visible spectral measureme nts, and a linear dependence of absorbance on the number of deposited layer s has been found. It was also found that the shape of UV-visible spectra de pends on the presence of ammonia in both gaseous and liquid phases. Other a mines, such as il-butylamine, can also affect the spectra. An attempt of ur ease immobilisation has been done using polyelectrolyte self-assembly. Comp osite films containing both Chromol and urease demonstrated the possibility of optical registration of enzyme reactions, in particular, decomposition of urea which releases ammonia. After immersion into urea solution, the sam ples show spectral transformations similar to those observed in the presenc e of ammonia. (C) 1999 Elsevier Science S.A. All rights reserved.