Amalia Kotsi presented successfully her Master’s Thesis entitled “ZnO nanostructures on polymeric substrates for the creation of a microfluidic device for bacteria lysis”

ABSTRACT

In this thesis, the formation, characterization and study of zinc oxide (ZnO) nanostructured surfaces on polymer substrates is described with the ultimate goal of their implementation for the creation of a microfluidic bacterial lysis device.

The use of nanomaterials, such as metal nanoparticles, has made it possible the development of new techniques for microbe lysis through mechanical and/or chemical means. The aim of this work is the cellular lysis of bacteria by exploiting the chemical properties and topography of the ZnO nanostructured surfaces. Specifically, ZnO nanostructures were grown on different polymeric substrates (SU-8, PDMS) using different concentrations of gel solutions acting as a seeding layer to hydrothermally grow ZnO nanostructures on them.

In microfluidic systems, especially in molecular diagnostic systems based on the detection of genetic material of microorganisms, cell lysis is one of the key functional steps. Modern research suggests the use of nanostructured surfaces due to the antibacterial effect of their topography as well as the production of active oxygen radicals from the ZnO surface. In microchannels with ZnO surfaces, a higher bacterial killing rate has been observed inducing DNA release, thus facilitating the subsequent steps of molecular analysis. In addition, a comparison of the topography of the structures grown under different conditions through the use of chemical plasma treatment (and without) was made, as well as the killing rate of E. coli bacteria was evaluated. The plate counting method for colonies multiplied in the nutrient was used at different incubation times of bacteria on the nanostructured surfaces in order to evaluate the antibacterial activity of the ZnO surfaces. This procedure allows the accurate determination of the antibacterial activity and the assessment of the effectiveness of the developed ZnO surfaces on bacteria killing, as expressed by the bacterial killing rate.