Fabrication and Characterization of Multifunctional Cellulose-based Nanostructures for Potential Biological Applications

Boon Kui, Ho (2022) Fabrication and Characterization of Multifunctional Cellulose-based Nanostructures for Potential Biological Applications. PhD thesis, Universiti Malaysia Sarawak.

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Abstract

Nowadays, there are many drugs were produced but sustainable drug delivery hardly to be achieved due to both poor selectivity and biodistribution. Besides that, some drugs such as antibiotics might not be effective against resistant strain bacteria and reduced effectiveness of antibiotics. Apart from that, increasing use of pesticide for treatment of rice blast which led to environmental issue such as water pollution. This has raised the demand for biodegradable nanomaterials offers an alternative approach for rice blast control instead of using pesticide. Therefore, cellulose was employed to drug delivery, antibacterial and antifungal applications due to its biodegradability and environmental friendliness. In this study, cellulose fibers isolated from paper wastes were functionalized via TEMPO-mediated oxidation to form carboxylic cellulose. Then, carboxylic cellulose acetate (CCA) was synthesized by reacting carboxylic cellulose with acetic anhydride in the presence of iodine as a catalyst. Next, CCA was prepared in the form of nanoparticles via nanoprecipitation. The obtained carboxylic cellulose acetate nanoparticles (CCA NPs) with a mean diameter of 96 nm were subsequently evaluated as the nanocarriers for the controlled release of drugs. Penicillin G as a model drug was loaded onto the CCA NPs via the adsorption process. Drug release profiles of Penicillin G from CCA NPs were evaluated in phosphate buffer solution (PBS) at different medium pH values (1.2, 7.4, and 8.6). Results showed that pH-responsive release of penicillin G from CCA NPs was released most slowly at a medium of pH 7.4 over 24 hours. In addition, preparation CCA NPs as an antibacterial nanocarrier and loaded with penicillin G against Gram (+) and Gram (-) bacteria was also explored. It was observed that prepared CCA NPs exhibited good antibacterial activity against methicillin resistant Staphylococcus aureus (MRSA) (+) Staphylococcus epidermis (+), Escherichia coli (-), Bacillus cereus (+), and Salmonella typhimurium (-). Also, loading of penicillin G onto CCA NPs could produce better antibacterial activities against both Gram (+) and Gram (-) bacteria strains. Interestingly, PenG-loaded CCA NPs against Methicillin resistant Staphylococcus aureus (MRSA) superbug which resistant to penicillin G has produced promising results with almost 98% of the bacterial cells were suppressed. This antibacterial study showed that antibiotics loaded CCA NPs has produced a synergistic effect as well as enhanced antibacterial activity against the growth of both Gram (+) and Gram (-) bacteria, strains tested. Apart from that, carboxylic cellulose was also further functionalized with a polyamine (PEI or PAMAM) via coupling reaction and used for nanoparticles synthesis. In addition, carboxylic cellulose was also fabricated into carboxylic cellulose nanoparticles via the nanoprecipitation process. The obtained carboxylic cellulose nanoparticles were undergoing further modification by incorporating metal ions via in situ approach to form metal functionalized carboxylated cellulose nanoparticles. The obtained cellulose derivatives nanoparticles were evaluated for antifungal activity against five isolates of pathogenic fungi (pyricularia oryzae). In vitro antifungal assay, indicated that that, PEI-cel NPs inhibit 28-49 % of Pyricularia oryzae at a concentration of 2 mg.mL-1. for metal functionalized carboxylic cellulose nanoparticles, Ag-carboxylated cellulose nanoparticles could inhibit almost 26-83.3 % of Pyricularia oryzae at a concentration of 0.25-2 mg.mL-1. Moreover, in the seed germination test, PEI-cel NPs and Ag-carboxylated cellulose nanoparticles exhibited a low phytotoxicity effect with germination rates of 66-97% and 81-98 %, respectively within a concentration of 0.125-4 mg.mL-1. These results revealed that the metal functionalized carboxylated cellulose nanoparticles and polyamine functionalized carboxylic cellulose nanoparticles can be potential candidates as the antifungal agent against rice blast fungi. Keywords: Carboxylic cellulose acetate nanoparticles, metal functionalized carboxylated cellulose nanoparticles, polyamine modified carboxylic cellulose nanoparticles, antifungal activity, antibacterial activity.

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