Investigation on the use of mesoporous titanium dioxide as a substrate for globin adsorption: a strategy for protein based (electro) sensing.
21 August 2018
Campus Drie Eiken, B0.05 - Universiteitsplein 1 - 2610 Antwerpen-Wilrijk (route: UAntwerpen, Campus Drie Eiken
Organization / co-organization:
Department of Chemistry
Vera Meynen & Karolien De Wael
PhD defence Stefano Loreto - Faculty of Science, Department of Chemistry
The development of electrochemical biosensors represents a very active field in chemical research. Despite this intensive research, little is known how to (better) control the immobilization of proteins and to maximize their activity preservation. Encapsulation of proteins in mesoporous materials is a common strategy to increase the protein’s stability. However, divergent results have been reported on the effect of confinement on the stability and activity of proteins upon adsorption in a mesoporous matrix. Indeed, adsorption of proteins on a solid surface is a challenging phenomenon as the adsorption kinetics and efficiency, as well as the stability and activity of the adsorbed proteins are highly dependent on many different factors Some of these factors, e.g. hydration and surface chemistry, have been often overlooked .
In this PhD thesis, I focus on the different aspects that have a vast influence on the adsorption of proteins in mesoporous material. The aim of this study is the investigation of several experimental parameters, such as buffer and pH as well as the material properties, e.g. pore size and surface chemistry, in order to optimize the protein’s adsorption and stability. In addition, the effect of the material properties on the protein structure, as well as on the protein activity, upon adsorption is evaluated. Mesoporous titanium dioxide (MT) is used as substrate for the protein adsorption. In fact, MT is very promising regarding its properties to encapsulate a protein with the aim of developing robust biosensors. To achieve this, a first step is taken to develop a simple but effective synthesis methodology that allows controlling the fast hydrolysis of titania, rendering MT with uniform pores of different sizes.
Afterwards, the adsorption of two different globin proteins, horse heart myoglobin (hhMb) and human neuroglobin (NGB), into MT is discussed. HhMb is used as a model protein to study the impact of the experimental parameters and the material properties on both the adsorption efficiency and the protein structure and activity. NGB has been recently discovered and its biological function is still unclear. Here, focus is put on the peculiar effect of the MT pore size and surface chemistry on the structure and activity of NGB upon adsorption.
In conclusion, this thesis addresses the different challenges concerning the development of electrochemical biosensors based on globin proteins and incorporated in MT. It shows the beneficial effect of the protein incorporation in the porous network on its stability and activity, when the right choices are made with respect to, among others, buffer, pH, pore size and surface chemistry.