Biocompatible Photochromic Diketopiperazine-based Supramolecular Hydrogelator Systems

Book excerpt: In the course of the last twenty years, the research interest in 'photochemical switches' highly increased. They react on light, which can be controlled with excellent spatiotemporal precision, yet it is orthogonal towards most elements of chemical and biochemical systems. Therefore, light is an attractive trigger to control or study biological function or functional materials. In this work, the excellent properties of azobenzene photoswitches were combined with the cyclic dipeptide structural motif, resulting in phototriggered supramolecular low-molecular-weight gelators (LMWGs). Hydrogels are soft materials, which often find application in biomedical context and can be formed by self-assembly of LMWGs. They classify by their self-healing properties, thixotropy, on-demand reversibility and stimuli responsiveness, for example to light. The photoswitches inside photochromic hydrogels react in spatiotemporal precision to light irradiation and are excellent candidates for photo-controlled drug release. The versatility of azobenzene containing DKP-Lys hydrogelators was demonstrated in this thesis.