Abstract
M.Sc. (Chemistry)
Gold nanorods (Au-NRs) are of great interest in many areas of science and technology owing to their versatility, optical and electronic properties. A very interesting property of Au-NRs is their ability to generate surface plasmon resonance in the near infrared region. This surface plasmon can be enhanced by increasing the aspect ratio of the Au-NRs and can be used for photo-thermal application. While there are simple synthetic methods that allow for shape control and aspect ratio of the Au-NRs, the synthesis of high aspect ratio Au-NRs still proved difficult and often associated with high surfactant concentration, sensitivity to reactants, and reproducibility problems. This study elucidates simplistic ways to synthesize high aspect ratio Au-NRs and their photo-thermal therapy application. High aspect ratio Au-NRs were prepared via a modified seed-mediated synthetic two-pot growth method. Several experimental conditions were altered to investigate their influence on the synthesis of the Au-NRs. The Au-NRs were functionalized using both ligand exchange (PAu-NRs) and gelatin over-coating (gelatin@Au-NRs) strategy to make them more biocompatible. The biological stability, cellular viability, antibacterial activity, and photo-thermal properties were investigated. In vivo photo-thermal therapeutic applications using functionalized PAu-NRs under NIR laser irradiation with a temperature cooling system was also assessed in a mouse model. The PAu-NRs was delivered to the metastatic tumor-bearing lymph node using the lymphatic delivery administration route. The anti-tumor effect of the treatment procedure was evaluated using an in vivo bioluminescence imaging system (IVIS), 3D high frequency ultrasound (VEVO) and histological analysis. The study shows that by using lower seed volume, lower pH and lower surfactants concentration, high aspect ratio Au-NRs can be synthesized with high reproducibility. In addition, the aging of reactants was found to influence the reproducibility of the Au-NRs. For the photo-thermal application, this route led to sufficient accumulation of the anti-cancer agent in the metastatic site within a short time. The delivery route afforded precise control over the treatment time and treatment conditions. The results showed complete tumour ablation and growth termination with no growth reoccurrence after the treatment. This research presents an alternative, non-invasive therapeutic protocol in the treatment of cancer metastasis.