Crosslinked silk fibroin hydrogels for biomedical applications

Name: Nuchada Suttenun

Organization : Mae Fah Luang University

keyword: Biomedical

LCSH: Biomimetic polymers

Classification :.LCCS: QT37

LCSH: Biomedical materials

Abstract: The Bombyx mori silk fibroin (SF) has received much attention as promising natural polymers for pharmaceutical and biomedical applications due to its excellent biocompatibility, permeability to gas and water, tunable mechanical properties, hydrophilicity and structural similarity to some tissues and extracellular matrices. Despite these benefits, silk gelation is uncontrollable with typical long-lag time characteristic thus, limiting its practical use as biomedical hydrogel matrices. A number of methods were employed to overcome this drawback. Nevertheless, most of them occurred under non-physiological conditions with potential of destroying the encapsulated compounds. Therefore, there is a need for new methods to speed up the silk gelation, while maintaining its superior properties. This study proposed two new methods, physical and chemical crosslinking, to fabricate biomedical SF hydrogels with improved physicochemical properties. The physical method was initiated by the addition of a biocompatible poly(ethylene glycol)diacrylate (PEGDA). Results indicated that PEGDA could accelerate the silk gelation kinetics and improve their water-resistance. The mechanism is associated with a formation of interconnected β-sheet structure, as illustrated by the SEM images and the shift of the characteristic IR absorption bands of the protein (amide I and amide II) towards lower wavenumber region. Moreover, the increased thermal properties, observed in the thermogravimetric analysis (TGA) thermograms, suggested preferential molecular interactions between the two components. Beside the PEGDA addition, the type of extraction solvent and the aging conditions were also found to affect the in vitro silk gelation. In order to fabricate the accelerated SF hydrogels, a combined use of a ternary CaCl2/Ethanol/Water solvent and a short aging program was suggested. For a chemical crosslinking, a homobifunctional protein crosslinker, O,O'-Bis[2-(N-succinimidyl succinylamino)ethyl]polyethylene glycol (NHSP) was employed under physiological conditions. The acylation reaction of SF and NHSP was found to complete within 24 h as convinced by the appearance of a new IR absorption peak around 1102-1104 cm-1, corresponding to the ether linkage of NHSP. The crosslinking produces hybrid interconnected porous architectures that stabilize the material in an aqueous media. Such network topology facilitates, prolonged delivery of the encapsulated rhodamine B dye. Similar behavior was also observed in the PEGDA-containing samples, particularly in the SF rich systems. The explanation for this was associated with the tightened network topology and the retardation effects mediated by strong molecular interactions between the dye and SF molecules. The proposed crosslinking methods had thus been proven to be capable of improving both gelation kinetics and properties of the silk-based biomedical hydrogels, making them more suitable for biomedical applications.

Mae Fah Luang University. The Learning Resources and Education Media Center

Address: Chiang Rai

Email: library@mfu.ac.th

Name: Patchara Punyamoonwongsa

Role: Advisor

Created: 2014

Issued: 2015

Modified: 2020-04-03

Issued: 2015-10-14

วิทยานิพนธ์/Thesis

application/pdf

CallNumber: Thesis QT37 N963c 2014

eng

DegreeName: Master of Science

Level: Master's Degree

Descipline: Applied Chemistry

Grantor: Mae Fah Luang University

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