Water soluble squarine and hydrogel applications

Squaraines represent an important class of organic dyes. Squaraines can be used as photodynamic therapy (PDT) agents, bioimaging and labeling agents, chemosensors, nonlinear optical materials, and photovoltaics due to their high absorption coefficients, photoconductivity, photostability, and quantum yields. However, squaraines are generally insoluble in water and biological fluids due to their hydrophobic nature. Therefore, there is an urgent need to the design and synthesis of water-soluble squaraines. In this thesis, a squaraine dye 1, which is completely soluble in water and in biological media, is designed to overcome some of the limitations squaraines encountered in biomedical applications such as PDT and bioimaging. The structure and properties of squaraine 1 were elucidated by spectroscopic methods including 1H NMR and 13C NMR, HRMS, absorption, and fluorescence. Furthermore, squaraine 1 was tested as a bioimaging and photosensitizing agent. Finally, the integration of squaraine 1 into the hydrogel network was investigated. To this purpose, the designed hydrogels were first synthesized and then characterized by FTIR, SEM, and TGA. It is noteworthy that these hydrogels were biocompatible and can be used as photosensitizers