Synthesis And Characterisation Of N-Doped Graphene Quantum Dots/Titanium Dioxide Nanocomposite As Photosensitiser In Photodynamic Therapy For Breast Cancer Treatment
| dc.contributor.author | Ramachandran, Pravena | |
| dc.date.accessioned | 2022-05-10T07:23:21Z | |
| dc.date.available | 2022-05-10T07:23:21Z | |
| dc.date.issued | 2021-03 | |
| dc.description.abstract | Titanium dioxide nanoparticles (TiO2 NPs) have been proven to be a potential candidate in cancer therapy, particularly in the application of photodynamic therapy (PDT). However, the application of TiO2 NPs is limited due to the fast recombination rate of electron (e-)/hole (h+) pairs attributed to their wider bandgap energy. Thus, surface modification is explored to shift the absorption edge to a longer light wavelength to allow penetration into deep-seated tumours. In this study, TiO2 NPs conjugated with N-doped graphene quantum dots composites (N-GQDs/TiO2 NCs) to extend the light absorption properties of TiO2 to longer near-infrared (NIR) wavelengths. A facile one-pot hydrothermal method was employed to synthesise N-GQDs with an average particle size of 4.40 ± 1.5 nm at optimum conditions with molar ratio citric acid (CA):ethylenediamine (EDA) (1:1) at 180 °C for 4 h and primary amine (EDA) as the N-precursors. The blue emissive N-GQDs have photoluminescence (PL) quantum yield of 80.2 %, exhibited excitation-independent PL emission at 442 nm, with an excitation wavelength of 340 nm. Whereas, the anatase TiO2 NPs were synthesised using microwave-assisted synthesis in the aqueous phase with an average particle size of 11.46 ± 2.8 nm, a small crystallite size (12.2 nm) and low bandgap energy (2.93 eV). Based on the X-ray photoelectron spectroscopy (XPS) analysis, it was found that the square-shaped TiO2 NPs synthesised at 600 W for 20 min under acidic conditions (pH 1.3) are self-doped TiO2 (Ti3+ ions). Furthermore, the TiO2 conjugated with N-GQDs were prepared via a two-pot hydrothermal method with an optimum 3-mL loading of titanium(IV) isopropoxide (TTIP). For the N-GQDs/TiO2 NCs, the shifting in the bandgap energy (1.53 eV) was prominent as the TTIP loading increased while persisting anatase tetragonal crystal structure with an average particle size of 11.46 ± 2.8 nm. Besides, the cytotoxicity assay showed that the safe concentration of the nanomaterials was from 0.01 mg/mL to 0.5 mg/mL as the cell viability decreased prominently at 1.0 mg/mL. Upon the photo-activation of N-GQDs/TiO2 NCs with NIR light, the nanocomposites generated reactive oxygen species (ROS) were mainly singlet oxygen (1O2) that caused more significant cell death in MDA-MB-231 than in HS27 cells. The activation of Caspase Glo-3/7 indicated that the treated cells undergo an apoptosis-based cell death pathway. Moreover, the mitochondrial membrane potential disruption has occurred in the cells further suggested N-GQDs/TiO2-mediated PDT treatment induced mitochondrial-dependent apoptosis. As such, the capability of the titanium dioxide-based nanocomposite in achieving desirable cellular outcomes upon photo-activation proved that it has good potentials as a photosensitiser in the PDT for breast cancer treatment. | en_US |
| dc.identifier.uri | http://hdl.handle.net/123456789/15249 | |
| dc.language.iso | en | en_US |
| dc.publisher | Universiti Sains Malaysia | en_US |
| dc.subject | Chemistry | en_US |
| dc.title | Synthesis And Characterisation Of N-Doped Graphene Quantum Dots/Titanium Dioxide Nanocomposite As Photosensitiser In Photodynamic Therapy For Breast Cancer Treatment | en_US |
| dc.type | Thesis | en_US |
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