Cell-based Detection System Research Articles

Cell-based detection of microbial biomaterial contaminations.

A major challenge in biomaterial synthesis and functionalization is the prevention of microbial contaminations such as endotoxins (lipopolysaccharides (LPS)). In addition to LPS, which are exclusively expressed by Gram negative bacteria, also other microbial products derived from fungi or Gram positive bacteria can be found as contaminations in research laboratories. Typically, the Limulus amebocyte lysate (LAL)-test is used to determine the endotoxin levels of medical devices. However, this test fails to detect material-bound LPS and other microbial contaminations and, as demonstrated in this study, detects LPS from various bacterial species with different sensitivities.In this work, a cell-based assay using genetically engineered RAW macrophages, which detect not only soluble but also material-bound microbial contaminations is introduced.The sensitivity of this cell-line towards different LPS species and different heat-inactivated microbes was investigated. As proof of principle a soft hydrophobic poly(n-butyl acrylate) network (cPnBA), which may due to adhesive properties strongly bind microbes, was deliberately contaminated with heat-inactivated bacteria. While the LAL-test failed to detect the microbial contamination, the cell-based assay clearly detected material-bound microbial contaminations. Our data demonstrate that a cell-based detection system should routinely be used as supplement to the LAL-test to determine microbial contaminations of biomaterials.

Bacterial Spore Based Biosensor for Detection of Contaminants in Milk

Milk and milk products comprise essential nutrients for all age groups. Hence ensuring the quality and safety of dairy products offered to the consumers is mandatory objective of the dairy industry. Bacterial spores one of the hardiest forms of life can be exploited as biosensing element over the cell based detection system because of longer shelf life of the spores. Bacterial spores in the presence of favorable conditions germinate into metabolically active vegetative cells. The ability of spores to carry out cycle between the spore state and germinated cell contributes to their attractiveness as biosensing systems. The presence of contaminants such as antibiotics, aflatoxin and bacteria affects the life cycle events of bacterial spores and hence can be exploited as platform for detection of aforementioned in milk. This review focuses on the application of bacterial spores as biosensing system for contaminants in milk system. Furthermore, we have focused our attention on the discussion of principal concepts of spore structure and spore germination and examples of spore based detection systems that have been achieved up until now to detect potential contaminants in milk in our laboratory.