EVALUATION OF 3D PRINTABILITY AND DRUG RELEASE OF DRUG-LOADED MICRONEEDLES

• Autor(a) principal: Viegas, Beatriz
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10362/147066
• topic: 3D Printing; Transdermal Drug Release; Microneedles; Digital Light Processing; Photocurable Resins; Sustained Release; Domínio/Área Científica::Engenharia e Tecnologia::Nanotecnologia

Microneedles (MNs) have powerful drug delivery abilities and have been considered a promising approach to enhancing the skin's permeability. MNs are commonly produced by traditional fabrication methods which may present several disadvantages. Therefore, in this dissertation, a new fabrication approach, named as Digital Light Processing (DLP), was employed to overcome the mentioned disadvantages. This printing technology was used to fabricate drug-loaded spear microneedles for sustained release applications. Biocompatible and biodegradable polymers: polyethylene glycol (PEG) and polyethylene glycol diacrylate (PEGDA) were used as the bio-based photocurable resins and carbamazepine (CBZ) as the model drug. In the MNs final prototype, the base is composed of PEGDA, and the needles are made of PEGDA / PEG loaded with CBZ. To ensure proper adherence to the building platform the structures were printed using 50 s of exposure time for the first layer and the optimized parameters, 3 mW/cm2 of UV intensity for 3 s, for the remaining layers. Whole printed MNs showed to have good printability and the tip angle was the most susceptible parameter to the printing process. Furthermore, all the printed MNs were consistent and presented a smooth surface. Post-printing curing conditions showed that ideal mechanical properties of the MNs base were obtained at 50 ˚C and 45 min. The influence of the total number of needles per design was evaluated and the design with higher needle thickness showed to be stronger as it presented higher fracture forces of 2.5 N/Needle. Both designs showed a good piercing capacity and no needle damage upon application, however, the array with a higher density of needles required a higher piercing force, 27 ± 2 mN/Needle. Lastly, the two designs with higher needle thickness demonstrated an increasing drug release throughout the entire experiment and after 5 h both designs had ~ 3 % of the drug released. Although only a tiny amount of drug was released throughout the printed MNs, these findings are promising and show the ability of DLP MNs to release drugs during extended periods.