Biocatalysis, a green alternative to conventional metal-based catalysis, has emerged as an industrially viable technology to develop valuable chemicals using biological catalysts such as enzymes. These enzymes offer multiple advantages across a wide spectrum of applications, spanning industries such as food, fine chemicals and pharmaceuticals. Due to their substrate specificity, stereo- and regioselectivity and milder operating conditions, biocatalysis is considered as a more sustainable and less polluting method to synthesize advanced chemicals.
In the last decades, the advances in biotechnology and information technology in combination with recombinant DNA technology have enabled access to a much larger pool of available enzymes and facilitated their industrial production. In addition to these advances, enzyme immobilization plays an important role in enabling their cost-effective application. Therefore, immobilization technologies have established “enzymes” as readily recoverable and recyclable heterogeneous catalysts with improved biocatalytic performance under industrial process conditions.
Enzyme immobilization encompasses a range of techniques, including both physical and chemical methods. Among these, the direct attachment of an enzyme to a solid support by a covalent bond stands out as the most widely used method. This approach ensures that enzyme molecules are securely anchored through bonds like amides, ethers, thioethers or carbamates, thus preventing potential enzyme leaching and guaranteeing the recyclability of the enzyme catalyst.
While organic resins have traditionally served as a common solid support for enzyme immobilization in industry, there exists a wide array of inorganic alternatives, including minerals, carbon materials and inorganic oxides. Silica is one of the most frequently applied inorganic supports due to its well-described surface functionalization and tailorable porous architecture. The enzymes are covalently attached to the hydroxyl groups of the mesoporous silica surface, typically shaped into spheres, pellets or beads. However, these shapes often lead to a high pressure drop, increased mass diffusion limitations and a high amount of attrition. Therefore, more and more research has been focused on the shaping of enzyme supports by using multiple Additive Manufacturing or 3D-printing techniques. 3D-printing allows the formation of specifically designed supports and highly porous complex structures, leading to an improved mass transfer efficiency as well as a high enzyme density due to the increased geometric surface area.
The objective of this PhD is to optimize Direct Ink Writing, a leading manufacturing technique in 3D-printed catalysts or catalyst supports, for designing porous ceramic supports. You will focus on designing porous silica supports, followed by surface modification using several alkoxysilanes to efficiently attach the enzyme catalyst to the 3D-printed support and achieve a high functional density. In order to evaluate the catalytic performance and demonstrate the promising potential of a 3D-printed support, the immobilized enzymes will be directly compared to the free-flowing form. Initially, the catalytic performance will be assessed in a batch reactor. However, the potential of immobilized enzymes on 3D-printed supports in flow will be evaluated in order to assess the ability to perform a continuous synthesis process.
VITO offers a PhD scholarship to the candidate for 4 years. The successful student will be enrolled at Delft University of Technology. The university promotor for this PhD will be Prof. Dr. U. Hanefeld. At VITO, the PhD candidate will work within the CAST (Coating and Shaping Technologies) and PROBIO (BIOprocesses and mild BIOmass PROcessing) team under the supervision of Dr. S. Mullens, Dr. B. Sutens and Dr. Y. Satyawali.
How to apply?
Applications should be submitted online and include a copy of your CV, diploma transcripts and a cover letter. Applications will be processed on a first come first served basis until a suitable candidate is found.
Call for the next VITO PhD jury closes January 7, 2024.
More information is available on PhD | VITO.