Date of Award

January 2023

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Chemistry

First Advisor

Julia Xiaojun Zhao

Abstract

The severe detrimental effect of nondegradable and toxic synthetic materials on the environment in the last couple of decades has led researchers to focus more on eco-friendly products such as building materials, medical instruments, sports, textile, and automobile industries. Lignocellulosic plants and their fibers are the first choices for both material and biological science researchers due to their chemical structure, abundance, low cost, and nontoxic nature. These plants are composed of three major biopolymers such as cellulose, hemicellulose, and lignin. Cellulose is the most abundant polymer. In the recent past natural fibers have attracted substantial importance as potential structural materials after the removal of noncellulosic biopolymers (hemicellulose and lignin). In recent years, nanomaterials have been incorporated into these natural fibers to enhance their performance as reinforcement agents in composites. Hemicellulose, on the other hand, is the second most abundant biopolymer present in the lignocellulosic fibers. Among the hemicelluloses present in these lignocellulosic fibers Arabinoxylan (AX) is a non-toxic, branched polymer with high viscosity and heat capacity. These properties make it appealing to researchers in biological fields. the branched polymeric structure of AX makes it suitable for targeted drug delivery systems research, due to its high viscosity and nontoxic nature it is also a good resource for scaffold preparation for cancer cell line growth. AX can form a gel at ambient temperature and can retain its structure even in high temperatures due to its high heat capacity this particular property makes it a well-suited candidate in 3-dimension (3D) bioprinting as life support. This thesis will focus both on developing natural fiber-based composites using nanomaterials to create a sustainable, durable, and stronger composite, and preparing a soft scaffold for breast cancer cell line growth using plant-based polymer.In the first project, silica nanoparticle-embedded jute fiber-reinforced composites were prepared. Jute fibers were washed with water to remove dust particles and then dried in sunlight for three days. After that, it was dried again at 80 °C in an oven for constant weight to prepare composites. The dried fibers were modified by chemical treatment with sodium hydroxide solution at varying concentrations under ambient conditions. The treated and untreated fibers were reinforced with different thermosetting resins to prepare composites by a molding technique. Silica nanoparticles (SiNPs) were synthesized using the Stöber method; 50 mL of absolute ethanol was mixed with 50 mL of distilled water and 5 mL of conc. ammonium hydroxide was added to the mixture, followed by adding 10 mL of tetraethyl orthosilicate (TEOS). The treated jute fiber was dipped in 36 % (3-chloro-2hydroxypropyl) trimethylammonium chloride (CHPTAC) solution in a water bath at 60 °C with continuous agitation for a cationization reaction. During the cationization, 15 % NaOH was added to cationized the fiber in three steps at an interval of 5 min, and the mixture was stirred again for 15 min. The cationized jute fiber was removed from the bath, rinsed several times with water, neutralized, and dried at ambient temperatures. The cationized jute fiber was introduced in the synthesized nano-silica to adsorb SiNPs. Then, the SiNPs reinforced cationized jute fibers were dried in a dark place at room temperature. These SiNPs impregnated fibers were reinforced with thermosetting resin to prepare composites by the hand molding technique. The properties of these prepared composites were characterized by tensile strength, elongation at break, FT-IR, SEM, XRD, etc. In the third chapter, AX was extracted from wheat bran, cattail, and jute by a modified method developed by Lopez et al. 100 g wheat bran was mixed with 1 L of 4.5 % potassium hydroxide (KOH) solution and stirred at 100 °C for 2 h. The resultant slurry was then centrifuged for 20 min at 8500 rpm, and the supernatant was collected. Twice the volume of 95 % ethanol was added to the collected supernatant, and the suspension was stored at 4 °C for 16 h to ensure complete precipitation of AX. The precipitant was collected by centrifugation and was washed thoroughly with distilled water to remove ethanol and excess KOH. Subsequently, the obtained AX was dried in a vacuum oven at 40 °C for 24 h and was lyophilized at −50 °C using a freeze-dryer. To prepare the scaffold for cell culture, 40 gm/mL of AX and hyaluronic acid (HA) were mixed separately in water at a rate of 40 mg/mL and the mixture was left in a shaker for 24 h. The scaffolds were prepared by combining the AX and HA solutions in different ratios (1:1, 1:2, 1:3, and 1:4). The cancer cell line, MDA MB 231 was added to the scaffolds, and their growth and proliferation were observed for several days. Among all scaffolds, jute stick AX showed promising results.

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