DEVELOPMENT OF MOLECULARLY IMPRINTED POLYMERS BY LIGHT-INDUCED 3D PRINTING

Molecularly Imprinted Polymers (MIPs) are artificial receptors fabricated through Molecularly Imprinted Technology, an interesting and emerging technique, which consists in creating cavities with the shape of a chosen template, within a polymeric matrix. So, MIPs can exhibit selectivity and specificity for a predetermined analyte, used in the imprinting procedure, and their aim is to mimic natural molecular recognition mechanism, typical of biological receptors. Additionally, MIPs present several advantages, like superior physical robustness and strength, resilience to elevated temperatures and pressures, lower cost, ease of preparation, and versatility in the choice of template, compared to biological receptors. Due to these characteristics, MIPs are gaining widespread attention over the last few decades in a variety of scientific and technological sectors, like drug delivery, artificial antibodies, chemobiosensing, separation science, purification, assay and sensors, and catalysis. This thesis is focused on the development of 3D printed MIPs, using Digital Light Processing (DLP) technique, which allows the creation of complex and self-standing 3D structures. Generally, the constituents of MIPs are the molecule of interest, that will act as the template, embedded in a mixture of functional monomer, a small molecule that interacts with the template, crosslinker, a molecule that is employed to form the polymeric matrix, and finally an initiator, to induce the polymerization reaction. In this work, the ingredients chosen are the antibiotic oxytetracycline (OTC) as the template; methacrylic acid (MAA) as the functional monomer; dipropylene glycol diacrylate (DPGDA) as the crosslinker and phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide (BAPO) as the photoinitiator. Three formulations with different ratios between the ingredients (MAA, OTC and DPGDA) have been studied, optimizing for each of them the printing parameters, to obtain MIPs with complex geometries. After assessing the ability of the investigated materials to operate as MIPs, by printing simple dots and by means of UV-Vis spectroscopy, more complex geometries were studied, i.e., filters constituted by the alternation of planes and pillars. Printing fidelity and the ability to capture template molecules were studied as well. At last, aiming at improving the surface area creating porosities within the matrix, formulations with salt were printed. As a result, 3D printed MIPs able to capture target molecules were successfully developed. This thesis is composed of five chapters: the first one describes the ingredients, their optimization for the fabrication of MIPs, and the different production techniques. The second one is focused on Additive Manufacturing and in particular on VAT polymerization and DLP. In the third chapter the experimental part is described, focusing on the materials and methods used during the thesis. Chapter four focuses on the optimization of printing parameters, along with analysis of results. Finally, conclusions are summarized, mentioning future perspectives.