Laser technology and 3D printing for production of biopolymer-based hollow microneedles patch for biomedical applications

One of the major challenges of transdermal drug delivery is the creation of methods that allow greater bioavailability of drugs. Many techniques have been proposed in order to address this issue such as hypodermic injections and transdermal patches. However, all presented several disadvantages, such as the requirement of administration by trained people and poor bioavailability. Thus, microneedles have emerged as a promising alternative, since they are less invasive and a painless method for delivering drugs through the skin. In this dissertation, a low-cost procedure was proposed, without resorting to microfabrication techniques for the production of hollow microneedles on laser technology and 3D printing using biodegradable and biocompatible polymers such as commercially available poly(lactic acid) (PLA) and the poly(hydroxybutyrate-cohydroxyvalerate) (P(HB-co-HV)) extracted from biomass. Laser technology was used to carve specific patterns on the PDMS that served as a mould for the production of needles, while 3D printing was used to produce a counter-mould in order to create a hollow profile in the microneedle when it is pressed onto the assembled mould-molten polymer. The best condition for the production of the moulds was obtained with the spiral pattern, a power of 50 W and a speed of 0.051 m/s. The first step of the production was performed successfully, and the microneedles produced were characterized by SEM, XRD and mechanical compression tests while the biomass was submitted to SEM-EDS, FTIR and XRD analysis. To demonstrate the feasibility of the second production step, the geometry of the counter-mould was optimized, and a macroscale proof of concept was performed using an insulin syringe to produce the hollow needle profiles. At the end of this work, the performance of P(HB-co-HV) in the production of microneedles was satisfactory, leaving good indicators on the feasibility of its use in biomedical applications such as the one studied.