Sol–gel luminescence biosensors: Encapsulation of recombinant E. coli reporters in thick silicate films

A class of sensing elements based on the encapsulation of genetically engineered bioluminescent Escherichia coli (E. coli) reporter strains in sol–gel derived silicates is described. We demonstrate the concept by the immobilization of these bacterial cells in thick silicate films. Heat shock, oxidative stress, fatty acids, peroxides, and genotoxicity reporting bacteria were incorporated in the sol–gel silicates and their luminescence response was compared to that of the non-immobilized culture. All the immobilized bacteria maintained viability and luminescence activity for several months. The bacteria–silicate hybrids can be used either as disposable sensors or in multiple use sensing test-kits, and they can be also integrated in early warning devices operated in continuous flow conditions. © 2002 Elsevier Science B.V. All rights reserved.