Periodontal disease is one of the most common oral diseases involving destruction of the tooth supporting apparatus and is responsible for the decay and loss of the periodontal structures in adults.Guided Tissue Regeneration (GTR) has recently gained recognition in the attempt to restore the lost periodontal tissues, promoting tissue integration, including the formation of new periodontal ligament functionally oriented to the newly formed cementum and alveolar bone.Recently, major advancements have been done in the development of membrane systems for the guided tissue regeneration (GTR) technique using innovative materials and processing techniques. However, most of them still do not fulfill all the physicochemical, biological and mechanical requirements, limiting their clinical application. Silk Fibroin (SF) has been recently recognized as a high potential material for several biomedical applications, including tissue regeneration. Taking into account that it is a structural protein, already spun by insects in nature, SF emerges as a prospective material to be processed by electrospinning, aiming at periodontal treatment. The basic principle behind this technique is the application of a high voltage over a polymeric solution suspended from a needle generating polymer nanofibers that will deposit under the form of a nonwoven mat. Amongst the most important parameters to achieve optimal processing conditions and fiber quality is the viscosity of the starting solution. This study investigates the possibility of combining a sonication treatment prior to electrospinning as a strategy to physically enhance the rheological properties of SF/poly (ethylene oxide) (PEO) solutions of different concentrations (10 %, 20 % and 30 % PEO (w/v)), and therefore to improve the spinability of the system.The influence of sonication time (0, 7.5, 15, and 20 minutes) on the solution properties was studied. The rheological tests indicated that sonication improved the viscosity of SF/PEO solutions. The electrospun SF/PEO membranes from the sonicated solutions demonstrated higher fiber diameter and improved mechanical properties in dry and wet conditions.Infrared spectroscopy, demonstrated that, although the SF membranes had undergone some conformational transitions with the increasing of sonication time, their structure was mainly composed by amorphous conformation. Permeability assays were also used as a complementary test, showing that the water vapor transmission range is high allowing for the diffusion of the nutrients while acting as a cell barrier. Finally, preliminary in vitro cell culture assays using primary cells from the periodontal ligament (PDLs) indicated that the developed membranes supported cell adhesion and proliferation indicating good cell viability as revealed by the DNA results. The present developed work constitutes a step forward towards the processing of viable electrospun SF-based membranes for periodontal regeneration since it demonstrates that it is possible to tune the viscosity of SF solutions to achieve optimal processing conditions using a simple sonication step prior to the electrospinning process, minimizing the amount of synthetic polymer to be used.
|Date of Award
|28 Mar 2017
- Universidade Católica Portuguesa
|Fang Yang (Supervisor), Ana Leite Oliveira (Co-Supervisor) & Sónia de Lacerda Schickert (Co-Supervisor)
- Mestrado em Engenharia Biomédica