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Tesis:

Development of a new biomimetic approach for the spinning of regenerated silkworm silk fibers

  • Autor: MADURGA LACALLE, Rodrigo

  • Título: Development of a new biomimetic approach for the spinning of regenerated silkworm silk fibers

  • Fecha: 2015

  • Materia: CONFICENCIAL

  • Escuela: E.T.S. DE INGENIEROS DE TELECOMUNICACION

  • Departamentos: TECNOLOGIA FOTONICA Y BIOINGENIERIA

  • Acceso electrónico:

  • Director/a 1º: PÉREZ RIGUEIRO, José

  • Resumen: In the first half of the 20$^{th}$ Century there was a grate development in the production of new manufactured polymeric fibers that starts with the production of regenerated cellulose. Along the second half of the 20th Century the focus of the manufactured fibers industry twisted from the development of new fibers to the improvement of the existing ones and artificial polymers gain interest. From this research effort of the fibers industry high-performance fibers like Nylon or Kevlar appeared. The appearance of these high-performance fibers led to a great expansion of the possible applications of fibers. Nowadays a branch of these multiple applications of the high-performance fibers is Medicine. Fibers are used as sutures and it has been proposed that they can be also used to build up scaffolds for Tissue Engineering. For these medical applications, besides the good mechanical properties of the fibers there are other interesting properties: biocompatibility and, eventually, biodegradability. In this context, the proof that natural silk does not induce inflammatory or allergic processes in human body and the possibility of building biodegradable silk structures has promoted a new research area focused in the production of silk-based biomaterials. To this boom have contributed the outstanding mechanical properties of silk fibers. Thereby, silkworm Bombyx mori silk show similar work to fracture to Nylon or Kevlar; being both values widely overcome by spider dragline silk. However the natural production of silk show important drawbacks. Farming of silkworm Bombyx mori has been carried out for thousands of years for the textile industry. Silkworm silk fibers are obtained from the cocoons. For that purpose, cocoons need to be degummed to remove the glue protein known as sericine that keep the silk fibers compact in the cocoon structure. Sericine can induce sever inflammatory responses, therefore, the complete removal of sericins is necessary in order to apply the silk fibroin in Medicine. However, the degumming processes that ensure the complete removal of this protein also damage silk fibers deteriorating their mechanical properties. Consequently, the development of a process to spin fibers with the composition of silk and with high mechanical performance is of immediate interest for biomedical applications. Additionally, the development of an artificial spinning process would offer the possibility of spinning fibers with properties that differ from those of natural silkworm silk. In this sense, the production of fibers with the composition of silkworm silk but with some characteristic properties of spider silk, i.e. supercontraction and recovery, would result in the emergence of new possible applications. To the moment many attempts have been launched to produce artificial silk but the production of high-performance artificial silk fibers under efficient conditions, in technical and economical terms, has not been still achieved. Most of the different attempts have been made using traditional spinning techniques like wet-spinning or dry-jet wet-spinning. But the few attempts made with new microfluidic devices did not show much promising results. Regarding to the physico-chemical conditions, artificial silk fibers have been produced using toxic solvents and/or coagulants or under high temperature processing conditions. Consequently, the spinning of artificial silk fibers under mild conditions (aqueous dopes, low toxicity coagulants and ambient temperature) is still a challenge to achieve. In this thesis, a new spinning process has been developed with the objective of spinning regenerated silkworm Bombyx mori silk fibers under mild conditions. The new spinning process tries to mimic certain characteristics of the natural spinning process like the dehydration of the dope and the ion exchange during the spinning process between the dope and the media. Differently from other spinning techniques, the new spinning process allows to control the shear forces exerted to the dope that play a critical role in the natural spinning process of silkworms and spiders. Besides, the new spinning process is a versatile technique that offers a wide set of parameters involved in the spinning process that can be varied. This work includes an initial study that explores a wide range of spinning conditions that allow the production of artificial silk whose properties are comparable to that of the natural material. In this sense, as it is developed bellow, it has been possible to prove that the new spinning process allow the spinning of high-performance artificial silk fibers under mild conditions. Consequently, the new spinning process appears as a promising spinning technique with ample opportunities for development.