As a result of improper handling, germ contamination can occur in wipe dispenser systems, which can lead to unnoticed contamination of the surfaces to be disinfected.

The Association for Applied Hygiene e.V. (VAH) recommends routine testing of the systems for germs using (cost-intensive) cultivation procedures.

The aim of the research project is a catch-sweep fluorescence indicator for continuous monitoring of the microbial status of wipe dispenser systems: The detection is based on the binding of germs to enzymatically hydrolysable anchor filaments immobilised on an indicator surface, which consist of single-stranded DNA and carry an aptamer sequence at the free end for binding Gram-positive or Gram-negative germs.

Several enzymatically non-hydrolysable peptide nucleic acid (PNA) activators are bound to the anchor filaments. Furthermore, PNA fluorescence reporters are immobilised on the indicator surface. Bound vital germs secrete nucleases which hydrolyse the anchor filaments releasing the PNA activators.

By hydrolysis of anchor filaments bound to the germ with simultaneous binding of the germ to neighbouring intact anchor filaments, the germ is transported across the indicator in a random walk pattern.

Released PNA activators activate the PNA fluorescence reporters on the transport track, resulting in a fluorescence signal visible to the naked eye when excited with suitable light (LED).