Improper use of wipe dispenser systems for the disinfection of surfaces can lead to germ contamination of these systems. The use of contaminated wipes, for example on surfaces in medical facilities, therefore unintentionally leads to contamination of the surfaces to be disinfected.

A catch-sweep fluorescence indicator was developed in this research project to continuously monitor the microbial status of such wipe dispenser systems. Such a quickly evaluable and inexpensive monitor offers advantages over the time-consuming and cost-intensive cultivation methods used to date.

The detection principle of the monitor is based on the binding of germs to enzymatically hydrolysable anchor filaments immobilized on an indicator surface, which consist of single-stranded DNA and carry an aptamer sequence at the free end to bind Gram-positive or Gram-negative germs.

Specific aptamers that bind to Gram-positive or Gram-negative bacteria were developed in disinfectant solutions using SELEX (Systematic Evolution of Ligands by EXponential enrichment).

The anchor filaments required as carriers of the aptamers were successfully immobilized on the indicator surface and proved to be enzymatically hydrolysable by both commercially available nucleases and nucleases secreted by bacteria.

Enzymatically non-hydrolyzable, locked nucleic acid (LNA)-based activators could be bound to the anchor filaments. After hydrolysis of the anchor filaments, the activators were released and hybridized to the LNA-based fluorescence reporters.

Binding of the activators to the fluorescence reporters generated a strong fluorescence signal that remained stable for several weeks.

The research results obtained show the functionality of the individual components of the Catch-Sweep-Fluorescence-Indicator-System. The complete indicator system therefore seems to be feasable as well.

The research report is available on request from FRT.