Microbial Sensors Based on Nanostructures

Some authors use the term “nanosensor” for biomolecules in nano molar concentrations acting as signals for living cells. In our review we emphasize on microbial sensors for detecting pathogens and on the “hardware” - the type of nanostructures used as a pad of bio sensing element. The main object is different type of nano-structured material used in the sensing process - non functionalized metal nanoparticles, metal oxides forming thin films and functionalized sensors as antibody-coated and aptamer-coated nanostructures and thin films. The latter have shown high selectivity and sensitivity and appear to be promising for future applications in medicine and environmental testing. Recent patents based on nanostructures for detection of clinically important pathogens are discussed. Our investigation proved the sensitivity of thin zinc oxide films to bacterial quantity of Gracilicutes and Firmicutes bacteria. The observed sensitivity was a single cell in a drop of water, but the change of potential to Pseudomonas cells was almost ten times higher than to Bacillus. It could be due not only to the bacterial type of cell wall but also to the type of dopant and the crystal structure of the ZnO thin film.