Biotech, Biomaterials and Biomedical: TechConnect Briefs 2015Biotech, Biomaterials and Biomedical TechConnect Briefs 2015

Sensors, Diagnostics & Imaging Chapter 3

Substrate addition and matrix optimization increased sensitivity and selectivity of the PLGA sensor, resulting in a stronger detection signal toward bacterial contaminations

N. Ibrisimovic, M. Ibrisimovic, A. Kesic, M. Mehmedinovic, M. Ibrisimovic
Faculty of Science, University of Tuzla, Bosnia and Herzegovina

pp. 183 - 186

Keywords: lipolytic enzymes, biosensor, polymer degradation, microbial detection

The aim of this work was to contribute to the development of a simple and cheap biomimetic sensor, providing a higher sensitivity and selectivity toward microbiological contaminations. An optimization of the matrix of the optical thin film sensor-chip, which setup was published in our previous work [1], required several parallel studies regarding bacterial growth and their enzymatic activity under different environmental conditions. The sensor is composed of: a) mirror layer and, b) biomimetic polymer [poly (lactic-coglycolic acid), PLGA]. The PLGA polymer, which is integrated in such two layer sensor setup, can be degraded by lipolytic enzymes excreted by microorganisms. Changes in the thickness of the polymer layer are resulting in a colour change of the sensor [1-4]. We have investigated the biology of several microorganisms and their metabolic pathways, and we were surprised to see that not all microorganisms produce an equal amount of lipolytic enzymes at the same stage of their reproduction. Monitoring of secretion of aminopeptidase and phospholipase enzymes from different bacteria such as Pseudomonas, Enterobacter, Proteus and Salmonella, and in correlation with their growth under different conditions, led to conclusion that there is no connection between a total bacterial count and amount of secreted lipolytic enzymes.