Public defence in Biomedical Engineering, M.Sc. (Tech) Joonas Ryssy

Opponent: professori Andreas Walther, Johannes Gutenberg University Mainz, Germany
Custos: Associate Professor Anton Kuzyk, Aalto University School of Science, Department of Neuroscience and Biomedical Engineering

The doctoral thesis will be publicly displayed 10 days before the defence in the publication archive of Aalto University.

Electronic doctoral thesis

Public defence announcement:

DNA is known as the carrier of genetic information. Not commonly known is that DNA has become a revolutionary building material. It can twist, fold, and take on many different shapes. The ability to fold DNA on command, referred to as DNA origami, is an exciting step in making molecular-level assemblies. The expectation is that DNA origami-based assemblies will someday reach the same level of complexity and functionality as natural molecular machines. Therefore, the mastery of DNA assembly into intricate structures but also the reconfigurability of the assemblies must be obtained first. However, controlling structures at such a microscopic level has been a challenge.

On the one hand, DNA molecules can be designed precisely and programmed to respond to a specific environmental stimulus. On the other hand, DNA allows us to make molecular-level devices with nanoscale precision. Moreover, DNA-based devices are inherently biocompatible and do not require harsh synthetic conditions. Thus, simple tools, materials, and methods can create complex and functional nanostructures and materials. Combining DNA-based nanofabrication with other materials, such as metal nanoparticles, highlight the precision of DNA as a nanoscale construct.

In this thesis, I demonstrate the inherent stimuli-responsiveness of DNA combined with gold nanorods to produce specific optical responses. Here, small molecules, temperature, and pH levels are used to cause structural changes in the DNA-based nano assemblies. Also, visible light is also utilized as an external stimulus. Furthermore, light is an inexpensive and green source. First, we implemented the light responsiveness into DNA-based nanostructures. We achieved this by coupling a photoresponsive buffer solution with acid-responsive DNA assemblies. In addition to the ability to control the DNA self-assembly with external light, the system responds with a gradient and is fully reversible. Secondly, we achieved the photoresponses in DNA-based materials by shining red light on DNA and gold nanorod-engineered hydrogels. When the gold nanorods are lit, they heat hydrogel, resulting in the thermoresponsive reconfiguration of DNA strands. As a result, we observed distinct and reversible optical responses in the form of color generation.

The results of this thesis advance the utility and applicability of DNA-based nanostructures and materials for new biocompatible technologies such as biosensors, molecular-level devices, and smart displays.

Contact details of the doctoral student: [email protected], +358400664985