In this thesis work, the use of sol-gel in biotechnology was investigated. This thesis has three independent projects with a common theme of bioprocess engineering. In the first chapter, the high cell density culture of cells in bioreactors was investigated. Specifically, human Foreskin Fibroblasts (hFFs) were cultivated in suspension culture using microcarriers. The goal was to passage hFFs on microcarriers without the use of trypsin. The result was that the yield of hFFs was significantly higher compared to static culture techniques. When cell cultures reach high densities, often the growth is limited by the accumulation of metabolic waste products. In the second chapter, enzyme-laced silica sol-gels were prepared and used for the in situ conversion of lactic acid to pyruvic acid, converting one of the two major metabolic waste products of cell culture into a cell-protecting growth substrate. Silica sol-gels are inorganic matrices that originate from an organic precursor. Sol-gels have been used to protect surfaces, like glass or sheet metal, from corrosion or scratches. In biotechnological applications, sol-gels can be used to encapsulate enzymes and other biologically active ingredients. Encapsulation of enzymes enables an easy recovery and reusability, reducing the cost per unit. One of the benefits of this technology is the simple integration into existing bioprocesses without contamination of protein samples due to the rigid nature of the silica sol-gel particles. This technology also has major implications in the areas of bioprocess engineering, such as tissue engineering and vaccine production by enabling an increase in the medium life span and therefore increasing cultivation times before medium changes, reducing production costs. The final chapter was another application of the sol-gel technology and was completed in an industrial setting. The goal was to develop a coating for safflower-derived oil bodies with silica sol-gel. This coating provided a customizable protection of oil body-associated proteins against digestion along the human gastro-intestinal tract. Overall these developments have examined key issues in current bioprocessing and come up with novel and practical solutions.