The Extracellular matrix (ECM) is a network of cell-secreted components that surrounds all cells in tissue. It is a highly organized and dynamic network that plays a crucial role in different cell-matrix interactions depending of the tissue. The ECM also provides mechanical support, regulates cell functions such as proliferation, adhesion and migration, helps in cell-cell signaling by creating a pathway to guide signals. The ECM is also a reservoir of biochemical compounds such as specific growth factors (GF). Much research has been spent on recreating these specific interactions in synthetic hydogels. This is done to selectively obtain a specific cellular response and to slowly obtain more knowledge on the function of the complex ECM. Some important factors that can be tuned in a synthetic hydrogels are the mechanical properties, e.g. stiffness, stress relaxation, or bioactivity. For my internship project, hydrazone crosslinked hydrogels are created that are formed using UV light. A hydrazone bond is a covalently reversible bond that is formed between a hydrazine and an aldehyde or keton, depending on the side groups. By incorporating the radical-mediated mechanism of the nitrobenzyl compound, an aldehyde is produced when irradiated with light of a specific wavelength. With this new approach an initiator-free and homogeneous network is formed, which allows for a controlled site-specific gel formation and peptide patterning.