Improving the potency of biomaterials for tissue growth

In recent years, it has been shown that synthetic biomaterials are not optimal supports for tissue growth due to their lack of intrinsic biochemical signalling potential. To improve the biological potency of these biomaterials and increase the reach of tissue engineering, key signalling proteins can be attached. However, when these proteins are attached via non-specific conjugation chemistries, they suffer a drastic loss of activity. There is therefore a need for site-selective approaches for protein- biomaterial conjugation. In this PhD, ligand-directed chemistry was studied to achieve this goal, with two new approaches to achieve site selective modification of proteins without the need for protein engineering. The first approach was based on using peptides as protein-binding ligands, while the second approach was based on the use of 2-pyridinecarboxaldehydes as N-terminal targeting ligands. This thesis will first introduce the peptide approach in Chapter 2, with details of the synthesis and modification of the peptides required, then will focus in Chapter 3 on the binding of these modified probes to their protein of interest. In Chapter 4, the use of these binding peptides for the formation of ligand-directed probes will be discussed. Chapter 5 will develop similar chemistry on 2- pyridinecarboxaldehydes, and finally Chapter 6 will describe the results using these two types of probes for the modification of proteins. Our results demonstrate that we can achieve site-selective modification of model proteins, representing the first traceless modification of protein using pyridinium oxime and N-acyl-N- sulphonamide (PyOx/NASA) system on a peptide in a traceless manner. With more optimization still needed, these preliminary results are important for the biomedical field in which protein-biomaterial conjugation is key for the formation of in-vitro tissue models for the study of various disease such as myocardial infarction, diabetes, and osteoarthritis.