Enzymes as biological catalysts can accelerate and regulate metabolic reactions in all living cells with high selectivity. Without biocatalysts, the chemical reactions in life process, such as digestion of food and synthesis of DNA could last forever. These days enzymes are used in the food, agricultural, cosmetic, and pharmaceutical industries as an environmentally-friendly alternative to conventional synthetic catalysts. However, the use of enzymes is rather limited due to a low long-term operational stability and difficulties in recycling enzymes from the reaction media. In order to increase the stability of enzymes and reuse them, it is therefore advantageous to immobilize them into solid materials. These solid materials as a support can form a protective environment and the immobilized enzyme can be easily separated from the reaction media.
In my PhD research, mesoporous silica particles were used as a promising support material for immobilization of enzymes. The porous structure provides a protective microenvironment in which the enzymes can tolerate extreme pH and high temperature. These silica particles have a large surface area and pore volume which make them suitable for confining the enzymes. The activity of enzymes after immobilization does not always increase, it is possible even to be reduced. Therefore, in order to use the immobilized enzymes in biocatalytic applications for industries, the immobilization process needs to be optimized based on the support material and the type of enzyme. For this optimization, there is a need to further understand the microenvironment inside the pores and the interactions between the support and enzymes.
In the first part of my thesis, I studied the dynamics of the enzyme immobilization in mesoporous silica particles by developing a fluorescence method and monitoring the process in real-time. Also the microenvironment inside the mesoporous particles was characterized. The effect of changes in microviscosity inside the pores on the dynamics behavior of the confined enzymes was discussed.
In the second part of this thesis, the distribution and location of the immobilized enzymes were studied with spectroscopy and microscopy techniques in different mesoporous silica particles. The effect of the pore morphology on the enzyme loading was studied in order to optimize the immobilization by choosing a suitable mesoporous silica particles. The research presented here can be used to rationally design the enzyme immobilization process for biocatalytic applications and making this method a suitable choice for industries.