In advanced applications of wound dressings, such as those applied for burns, the presence of pathogenic bacteria in the wound cannot be tested directly without compromising the mode of action of the dressing. A promising strategy for on-line monitoring the presence of bacteria in wounds is the implementation of a colorimetric sensor in such a dressing. Release and activation of the signaling moiety should occur exclusively in the presence of pathogenic bacteria. For application in infection signaling dressings, the natural pathway of bacterial toxin action is exploited in our work to selectively release colorimetric signaling molecules from hydrogels or from block copolymer containers. The responsive hydrogels comprise chitosan that is functionalized covalently with fluorogenic or chromogenic substrates or is loaded with polymersomes of novel hyaluronic acid-block-polycaprolactone and hyaluronic acid-block-poly(lactic acid) copolymers. Enzyme-permeable hydrogels could be obtained that were functionalized with alanyl-alanyl-phenylalanin-7-amido-4-methylcoumarin and 4-nitrophenyl �-D-glucuronide for the detection of the enzymes chymotrypsin and �-glucoronidase, respectively. Systematic variations of film thickness, substrate loading and enzyme concentration afforded quantitative enzyme-response curves using fluorescence and UV-Vis spectroscopy, respectively, and finally successful detection tests with E. coli. In addition first results of hydrogel - polymersome hybrids will be discussed. Our new approach will provide a simple, yet effective optical indicator of bacterial infection in wound dressings and other controlled release applications.

Detection of pathogenic bacteria via reporter-loaded biopolymer thin films

246th National Meeting (2013)

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