Design, development and functionalization of 3D printed air filters with antibacterial properties

3D printing, or additive manufacturing, is becoming increasingly important in the biomedical field due to the possibility of developing affordable custom devices with high flexibility in terms of materials, personalization, complexity and high precision. However, surface treatments and modifications are often needed to enable the required bio-functionality characteristics, such as biocompatibility, wettability or bioactivity. The aim of this work is to develop air filters 3D printed by Digital Light Processing (DLP) with antibacterial properties. DLP is based on the photopolymerization of liquid polymer resins and allows a rapid printing of objects with high resolution. In this thesis work, two strategies were followed: on the one hand, the design and fabrication of complex geometries which can reduce the microorganisms’ flow; on the other hand, a study of surface functionalization to obtain the desired final properties. Different printable formulations based on acrylic monomers were studied, optimizing printing parameters to obtain the designed geometries; subsequently, different surface functionalization methods (conventional heating, microwave heating, dip-coating and chlorination) were compared to impart bacterial adhesion characteristics to the filters. In this context, arginine, agmatine, dopamine and polyethylenimine were used as grafting agents. Here the goal was to exploit functional groups to promote microorganisms’ adhesion and killing. At last, biological studies were performed evaluating bacterial adhesion and proliferation. The effectiveness of the filters was studied with Gram-positive and Gram-negative bacteria, achieving promising results for the implementation of these devices. This thesis work was performed in collaboration with Instituto de Ciencia y Tecnología de Polímeros (ICTP-CSIC) and Institute for Biofunctional Studies of the Universidad Complutense (UCM) in Madrid.