Singh, Moganavelli.Gounden, Varshan.2026-05-062026-05-0620252025https://hdl.handle.net/10413/24376Masters Degree. University of KwaZulu-Natal, Durban.Cancer is a severe disease, devastating lives worldwide. Despite the numerous benefits of anticancer medication, their efficacy is compromised by insufficient selectivity and rapid metabolic degradation. In response to the requirement for novel drugs with improved therapeutic efficacy, delivery systems are being developed to mitigate the adverse effects of chemotherapy. The management of chronic wounds is a significant yet often overlooked concern, vital for preserving the mental and physical welfare of patients and enhancing their overall quality of life. In recent years, the application of hydrogels has significantly mitigated deficiencies in drug delivery and wound healing due to their similarity to the extracellular matrix (ECM) and stimuli-responsive properties, which facilitate drug release from contracting polymer chains in response to changes in pH, light, and temperature. Chitosan (CS) is an ideal, natural, and biologically compatible polymer that has a structural resemblance to glycosaminoglycans in the ECM and contains NH2 and OH groups that are functionally significant for its pH sensitivity and conformation. Gold nanoparticles (AuNPs) serve as inert, non-toxic physical crosslinkers for the development of "reversible" hydrogels utilizing electrostatic attraction with the cationic CS. This study outlines the synthesis of a CS hydrogel, physically cross-linked with AuNPs, followed by the encapsulation of 5-FU. The physicochemical properties of the CS, CS-Au, and CS-Au-5-FU hydrogels were analysed, and the identification of distinctive peaks in Fourier transform infrared (FTIR) spectroscopy, along with a peak at 530 nm under UV-visible spectroscopy, confirmed their successful synthesis. Transmission electron microscopy (TEM) confirmed the production of spherical nanoparticles (NPs) with an average diameter of approximately 89.31 nm. Scanning electron microscopy (SEM) demonstrated a porous network surface morphology for the CS and CS-Au hydrogels, conducive for diffusion and functioning as a synthetic extracellular matrix. The zeta potentials recorded using dynamic light scattering (DLS) were +11.1 ± 0.1 mV and +15.87 ± 1.18 mV for the CS-Au and CS-Au-5-FU hydrogels, respectively, suggesting moderate stability of the NPs. CS can function as a steric stabilizer to enhance the overall stabilization of the NP. Rheological analyses revealed a non-Newtonian shear-thinning property, characterized by a progressive reduction in viscosity with an increasing shear rate, along with a thixotropic behavioural characteristic attributed to hydrogel recovery following shear stress. This indicated a suitability for injection in vivo and application on dynamic wound surfaces. A thermal stability test using thermogravimetric analysis (TGA) demonstrated enhanced stability for the CS-Au hydrogel relative to the CS hydrogel due to physical crosslinking, as evidenced by a 21.21 C increase in the endothermic peak. The pH sensitivity and reswelling of the CS-Au hydrogel were examined, revealing a significant pH-dependent uptake in water. At pH 4.5, the hydrogel achieved a higher equilibrium quicker than at pH 7.4 and pH 10.5. This can be attributed to an increased concentration of protonated hydroxyl and amino groups, in tandem with the relaxation of the polymer chains enabling water absorption. It was determined that the CS-Au hydrogel attained a favourable drug (5-FU) loading capacity of 77.71%. An in vitro lysozymemediated degradation study of the CS-Au and CS-Au-5-FU hydrogels demonstrated a natural, progressive degradation profile that facilitated cellular proliferation and removal from the body. The drug release studies conducted in simulated cancer and physiological microenvironments indicated a sustained, pH-dependent release with specificity for the acidic cancer microenvironment (pH 4.5 and 6.5). The in vitro 3-(4,5-dimethylthiazol-2-yl)-2,5- diphenyltetrazolium bromide (MTT) cytotoxicity assay was performed on three human cell lines: HEK293 (embryonic kidney), HeLa (cervical carcinoma), and MCF-7 (breast adenocarcinoma). The results demonstrated a notable specificity of the CS-Au-5-FU hydrogel for the cancer cells (HeLa and MCF-7) and a diminished cytotoxicity in the non-cancer cells (HEK293). Minimal cytotoxicity was observed at all hydrogel concentrations, with some proliferation noted at 20 μg/ml for the CS and CS-Au hydrogels in the HEK293 cells. This suggests suitability for wound healing applications. The scratch assay illustrated the complete closure of the wounds at low concentrations (15.63 and 31.25 μg/ml), confirming the capacity of the hydrogel to imitate the extracellular matrix (ECM). The positive findings from this study confirm the potential of these CS-Au hydrogels to function as smart in vitro delivery systems and scaffolds for wound healing, warranting additional optimizations and in vivo studies.enCancer.Gold-nanoparticles.5-fluorouracil, cytotoxicity.Thesis