Hygiene quality management (QM) systems are of great importance in hygienically demanding areas (e.g. food and pharmaceutical industry, cosmetics and health sector). Hygiene and disinfection plans comprising regular cleaning and disinfection measures are important components of these QM systems. For analysing quality of such cleaning and disinfection measures random-check like controls are carried out routinely. Currently, contact plates are used for sampling of surfaces.

After sampling, contact plates must be incubated and analyzed by external microbiological laboratories. This requires at least 2 days (determination of total germ count and hygienically relevant microorganisms) and results in high costs. Another major disadvantage is the necessity to remove microorganisms from surfaces before qualitative and quantitative determination.

In particular in case of structured surfaces, microorganisms located in deepenings are often not detected. Therefore, there is a strong need of innovative methods for contemporary determination of both hygienically relevant microorganisms and total germ count on surfaces within a self control.

A new method for photoacoustic determination of hygiene status on surfaces by means of nano valve nanoparticles was therefore developed. Oxaloacetic acid is included in antibody based nano valve nanoparticles.

Nano valves are opened on contact with living microorganisms by binding of antibodies to microorganisms, oxaloacetic acid is released and converted by decarboxylase with carbon dioxide separation. Resulting carbon dioxide increase is detected in the gas phase by photoacoustic spectroscopy.

The research report is available on request from FRT.