Date of Award
Spring 2019
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Dentistry
First Advisor
Tayebi, Lobat
Second Advisor
Hashimoto, Lance
Third Advisor
Gaffney, Joseph
Abstract
Objective: To formulate a thermoreversible hydrogel using methyl-cellulose, carbon dots and inorganic salts to achieve physiologically compatible gelation temperature; to test cytotoxic effects of formulation against dental pulp stem cells.Materials/Methods: A 5% w/v methylcellulose (MC) solution was prepared and equal volumes of NaCl aqueous solution were added to make various sodium chloride salt concentrations and reach the final MC concentration of 2.5%. Samples were analyzed using a shear rheometer to monitor complex shear viscosity as a function of temperature to arrive at onset gelation temperature closest to targeted temperature. Carbon dots were synthesized by thermal method using ammonium citrate as nitrogen precursor. Dental pulp stem cells were isolated from extracted third molars and cultured under standard aseptic conditions. Cells were seeded onto well plates containing optimized hydrogels and cell proliferations were monitored at 1, 2, 5 and 14 days. Cytotoxicity of the samples was tested against a positive control (UltraCal Calcium Hydroxide) and a negative control (cells with no gel).Results: The optimal gelation temperature (30-37 °C) was achieved by using 2.5% methylcellulose, 8.0% sodium chloride and 5 ug/mL carbon dots. The gelation temperature was found to be significantly affected by the salt concentration and slightly affected by concentration of carbon dots. The gelation temperature was inversely proportional to the NaCl concentration. Cytotoxicity testing of hydrogels revealed adequate proliferation of dental pulp stem cells when compared to values produced by calcium hydroxide, indicating a level of biocompatibility conducive to proliferation of these cells.Conclusion: Cellulose-based hydrogels incorporating carbon dots can be considered as a potential formulation for use as a scaffold during regenerative endodontic procedure. This study utilizes a simple, inexpensive approach to fabricate such an injectable non- cytotoxic gel. However, antibacterial effect of the gel needs to be evaluated and is the subject of our future studies.