Photothermal cancer therapy A direct method of accessing and destroying tumour cells can be accomplished by photothermal cancer therapy or photodynamic therapy (PDT). This procedure is known to treat small tumours that are difficult to access and avoids the drawbacks (adverse effects) of conventional methods, including the unnecessary destruction of healthy tissues. The cells are destroyed by exposure to light, rupturing membranes causing the release of digestive enzymes. AuNPs have high absorption cross sections requiring only minimal input of irradiation energy. Human breast carcinoma cells infused with metal<unk>  in vitro have been shown to have an increase in morbidity with exposure to near infrared (NIR). Short term exposure in vivo (4–6 minutes) to NIR had undergone the same effect. Hirsch et al observed that extreme heating in tumours would cause irreversible tissue damage including coagulation, cell shrinkage and loss of nuclear straining. Results of their in vivo nanoshell therapy of mice revealed penetration of the tumor ~5mm.The metal particles were tuned to high absorption and scattering, resulting in effective conversion of light into heat covering a large surface area. The El-Sayed group studied AuNP effects in vitro and in vivo. They determined that the NIR wavelengths were converted into heat on the picosecond timescale, allowing for short exposure of CW to minimize possible exposure to healthy cells. In vitro, photothermal therapy was used in oral epithelial cell lines, (HSC 313 and HOC 3 Clone 8) and one benign epithelial cell line (HaCaT). El-Sayed et al found that the malignant cells that had undergone incubation in AuNPs conjugated with anti-epithelial growth factor receptor (EGFR) required half the energy to destroy a cell than a benign cell. Their material included<unk>  coated silica nanoshells that could selectively absorb NIR waves. The particles were tuned by varying the thickness of the Au shell and changing the size of the silica core. In exposing these particles to NIR, the efficacy of Au was measured through the decrease of EFGR in oral squamous carcinoma cells. There are various biotechnological advances for in vivo delivery of drugs. To effectively target the malignant cells, the AuNPs were conjugated by polyethylene glycol, a process known as PEGylation. This masks the foreign particles from the immune system such that it arrives at its destination and increases circulation time in the system. Antibody conjugation lines the surface of the<unk> with cell markers to limit spread only to malignant cells. In vivo testing of mice that developed murine colon carcinoma tumour cells. They were injected with the solution of AuNPs that were allowed to spread after 6 hours. Surrounding cells were swabbed with PEG and exposed to laser treatment for detection of abnormal heating indicating areas where Au nanoshells may have gathered. The injected area was also swabbed with PEG to maximize light penetration. Despite the unquestionable success of<unk>  nanorods or nanoshells as photothermal agents in preclinical research, they have yet to obtain the approval for clinical use because their size is above the renal excretion threshold. In 2019, the first NIR-absorbing plasmonic ultrasmall-in-nano architecture has been reported, and jointly combine: (i) an efficient photothermal conversion suitable for multiple hyperthermia treatments, and (ii) renal excretion of the building blocks after the therapeutic action. Radiofrequency therapy X-ray radiography procedures involves the diagnosis of cancer cells through the process of image acquisition. These techniques rely on the absorption of x-rays on the exposed tissue in order to improve image quality. In certain radiological procedures such as Radiofrequency therapy, a contrast agent is injected into the targeted cancer tissue and result in increased x-ray attenuation. Radiofrequency therapy treatment involves the destruction of tumor cancer tissue cells through the differential heating of cancer tissue by radio-frequency diathermy. This differential heating is a result of the blood supply in the body carrying away the heat and cooling the heated tissue.<unk><unk>  are excellent absorbers of x-rays, due to its high atomic number of 197Au. This allows for a higher mass of the element, providing for a greater area of x-ray absorption. By acting as a contrast agent and injected into cancerous tumor cells, it would result in a higher dose of the cancerous tissue being exposed during radiotherapy treatment. Additionally<unk><unk>  are more efficiently removed from cells of healthy tissue, in comparison with cancer cells - a feature that makes them a promising radiosensitizers Angiogenesis therapy Angiogenesis is a process involving the formation of new blood vessels from pre-existing vessels. It involves the degradation of the extracellular matrix, activation, migration, proliferation, and differentiation of endothelial cells into vessels. It is said to play a large part in the growth and spread of cancer cells. The process of angiogenesis involves the use of both promoters and inhibitors, balancing the process by only forming new blood vessels when needed. Examples of promoters include Vascular Endothelial Growth Factor (VEGF) and fibroblast growth factor (FGF) Examples of inhibitors include Vascular Endothelial Growth Factor Receptor 1, etc. Tumor progression occurs as a result of the transition from a tumor in the dormant proliferation stage to the active stage as a result of oxygen and nutrients. This active stage leads to a state of cellular hypoxia, which causes an increased regulation of pro-angiogenesis proteins such as VEGF. This results in the spreading of inflammatory proteins and cancer cells alongside the newly created blood vessels. AuNPs have the ability to inhibit angiogenesis by directly coordinating to heparin binding growth factors. They inhibit phosphorylation of proteins responsible for angiogenesis in a dose dependent matter. At concentrations 335-670 nM, almost complete inhibition of phosphorylation was observed. As a consequence of angiogenesis, rheumatoid arthritis has been found to develop due to the greater ability to spread inflammatory proteins. Through the inhibition of angiogenesis, the reduction of rheumatoid arthritis is prevalent. In addition, angiogenic inhibitors have a critical limitation due to the instability of biological conditions and high dosage required. To counter this, an emerging strategy for the development of therapies targeting tumor-associated angiogenesis through the use of nanotechnology and anti-angiogenic agents was developed, known as anti-angiogenic therapy. This approach solved the limitation instability by speeding up the delivery of angiogenesis inhibitors.<unk><unk>  display anti-angiogenic properties by inhibiting the function of pro-angiogenic heparin-binding growth factors (HG – GFs), with prime examples being the vascular endothelial growth factor 165 (VEGF165) and the basic fibroblast growth factor (bFGF) - both of which are pro-angiogenic promoters. Studies by Rochelle R. Arvizo, et al. have shown that the use of AuNPs of various size and surface charge plays an important role in its inhibitory effects. In today’s biological fields, the use of nanotechnology has allowed for the indirect use of AuNPs to deliver DNA to mammalian cells; thereby reducing tumor agents and increasing efficiency of electron transfer by modulating the activity of glucose oxidase. Current ongoing research by the Mayo Clinic laboratories includes the examination of AuNPs as messengers to deliver reagents capable of manipulating the angiogenic response in vivo. Current angiogenic inhibitors used today which are approved by the USFDA to treat cancer is Ayastin, Nexavar, Sutent and Affinitor. Anti-bacterial therapy<unk><unk>  are used as bacteria targeting particles in antibacterial therapy. The therapy targets bacteria with light absorbing<unk><unk>  (10 nm, 20 nm, 40 nm) conjugated with specific antibodies, thus selectively kill bacteria using laser. Studies has shown the effectiveness of this method on killing Staphylococcus aureus, which is significant human pathogen responsible for a wide range of diseases such as skin and wound infections, toxic shock syndrome, septic arthritis, endocarditis, and osteomyelitis. In this system, the bacteria damage is caused by inducing strong laser which leads to overheating effects accompanied by the bubble-formation phenomena around clustered<unk><unk> . The selective targeting of S. aureus was performed using a monoclonal antibody to one of the major surface-clustered proteins, protein A (spa), which is linked to the peptidoglycan portion of the cell wall. Monoclonal antibodies ensure the targeting of the specific cell, which is essential to this mechanism. Killing efficiency depends on local overheating effects accompanied by the bubble-formation phenomena, the bubble formation would enhance the PT killing effect.Better heating efficiency results from an enhanced ability to confine the nanosecond laser-pulse within the nanocluster’s size. Overlapping of bubbles from different<unk>  within the nanoclusters decreases the bubble-formation threshold. An increase in the cluster’s average local absorption and its potential redshifting (from 525 nm for a single<unk>  spherical<unk> to 700–800 nm for nanoclusters) in response to plasmon-plasmon resonance. Drug vectorization Another way in which AuNPs can be used in cancer therapy is as agents for targeted drug delivery. Research shows that AuNPs can be easily functionalized and conjugated with a variety of molecules, including<unk> utic drugs such as Doxorubicin. One major complication with the current methods of treating cancer with<unk>  is that treatment is not optimized to specifically target cancer cells and the widespread distribution of<unk> utic drugs throughout the body can cause harmful side effects such as naseua, hair loss, and cardiotoxicity. Since many of the characteristics of AuNPs allow
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