Cancer-Battling 'Nanoshells' Presented By: Muhammad Zain Akram (NT-1007)

Why Nanotechnology ? Conventional chemotherapy employs drugs that are known to kill cancer cells effectively. But these cytotoxic drugs kill healthy cells in addition to tumor cells, leading to adverse side effects such as nausea, neuropathy, hair-loss, fatigue, and compromised immune function

Why Nanotechnology ? Nanoparticles can be used as drug carriers for chemotherapeutics to deliver medication directly to the tumor while sparing healthy tissue. Nanocarriers have several advantages over conventional chemotherapy

Advantages of Nanocarriers over conventional chemotherapy Nanocarriers have several advantages over conventional chemotherapy. They can: protect drugs from being degraded in the body before they reach their target. enhance the absorption of drugs into tumors and into the cancerous cells themselves. allow for better control over the timing and distribution of drugs to the tissue, making it easier for oncologists to assess how well they work. prevent drugs from interacting with normal cells, thus avoiding side effects.

Fighting Cancer With Nanoshells Moving away from conventional chemotherapeutic agents that activate normal molecular mechanisms to induce cell death, researchers are exploring ways to physically destroy cancerous cells One such technology “Nanoshells” is being used in the laboratory to thermally destroy tumors .

Fighting Cancer With Nanoshells Nanoshells can be designed to absorb light of different frequencies, generating heat (hyperthermia). Once the cancer cells take up the nanoshells (via active targeting), scientists apply near-infrared light that is absorbed by the nanoshells, creating an intense heat inside the tumor that selectively kills tumor cells without disturbing neighboring healthy cells. Similarly, new targeted magnetic nanoparticles are in development that will both be visible through Magnetic Resonance Imaging (MRI) and can also destroy cells by hyperthermia.

What are Nanoshells?? Metal nanoshells are a novel type of composite spherical nanoparticle consisting of a dielectric core covered by a thin metallic shell which is typically gold. Nanoshells possess highly favorable optical and chemical properties for biomedical imaging and therapeutic applications. By varying the relative the dimensions of the core and the shell, the optical resonance of these nanoparticles can be precisely and systematically varied over a broad region ranging from the near-UV to the mid-infrared.

Significance of Nanoshells Nanoshells have a core of silica and a metallic outer layer. These nanoshells can be injected safely, as demonstrated in animal models. Metal nanoshells are a class of nanoparticles with tunable optical resonances. Nanoshells should work in most soft tissue tumors but would be most effective on cancers that can't be removed surgically because they're in an awkward location, such as in the brain. recent study shows that you can inject nanoshells intravenously and they will accumulate in tumor sites because the blood vessels in tumors are leakier than elsewhere in the body.

Cancer Battling Gold Nanoshells Gold nanoshells are spherical particles with diameters typically ranging in size from 10 to 200 nm . They are composed of a dielectric core covered by a thin gold shell. As novel nanostructures, they possess a remarkable set of optical, chemical and physical properties, which make them ideal candidates for enhancing cancer detection, cancer treatment, cellular imaging and medical biosensing. Gold nanoshells are unique in that they combine many ideal features in a single particle. Nanoshells can be engineered to target cancerous cells and at the same time designed to interact with specific wavelengths of light. Depending upon the wavelength of incident light, nanoshells can either scatter or absorb light, creating applications as both a cancer imaging agent or therapeutic one.

They can be tuned to preferentially absorb or scatter light at specific wavelengths in the visible and near - infrared ( NIR ) regions of the spectrum. In the NIR ‘ tissue window ’ , light penetration into tissue is optimal. Nanoshells tuned to absorb NIR radiation are particularly useful as mediators of photothermal cancer therapy because they efficiently convert absorbed radiation into heat, and are thermally stable at therapeutic temperatures. Furthermore, nanoshells preferentially accumulate at tumor sites due to their nanoscale dimensions.

Gold Nanoshells Called nanoshells, the golden balls have a bit of mica in their center and can be designed to absorb radiation at various frequencies

What's special about gold nanoshell? Nanoshells can come in many shapes and sizes, but all are composed of a core and a shell. The core is the interior part and the shell is the material coated around the core. In the case of a gold nanoshell the core is a ball of silica and the shell is a thin layer of gold. Gold nanoshells have similar properties to gold nanoparticles , but have the added benefit of being tunable to different wavelengths of light. The human body only allows certain wavelengths of light to pass through the body; these wavelengths are outside the visible spectrum (colors we can see) and are near-infrared light. Gold nanoshells are tuned to these wavelengths of light so that they can trigger properties of nanoshells without opening the body

What's special about Gold nanoshell? The optical response of gold nanoshells depends dramatically on the relative size of the nanoparticle core and the thickness of the gold shell. By varying the relative core and shell thicknesses, the color of Gold nanoshells can be varied across a broad range of the optical spectrum that spans the visible and the near infrared spectral regions . Gold nanoshells can be made to either preferentially absorb or scatter light by varying the size of the particle relative to the wavelength of the light at their optical resonance.

Synthetic protocol for the fabrication of Gold Nanoshells Grow or obtain silica nanoparticles dispersed in Solution. Attach very small (1-2 nm) metal “seed” colloid to the surface of the nanoparticles via molecular linkages; these seed colloids cover the dielectric nanoparticle surfaces with a discontinuous metal colloid layer. Grow additional metal onto the “seed” metal colloid adsorbates via chemical reduction in solution.

Battle Against Cancer Gold nanoshells that are designed to absorb radiation at various frequencies, absorb certain types of radiation becoming a new weapon in the ongoing battle against cancer. Once the nanoshells are attached to the cancer cells, only laser light is needed to treat the cancer. Near infrared (NIR) light passes through the body and reaches the gold nanoshell. The tuned gold nanoshells receives the NIR light and convert the light energy into heat, killing the cancer cells

Near infrared light is a type of low-energy radiation not absorbed by living tissues. However, the nanoshells can be designed to absorb this light, which heats them up. Nanoshells use surface plasmon resonance, or a wave-like excitation of electrons along the surface, to convert laser light into heat. Because nanoshells are metallic on the outside and small in size, the laser light interacts with the shell, causing surface plasmon resonance. Electrons in the gold prefer to have low energy, so they give off any extra energy as heat to the surrounding environment, including the attached cancer cell. The Texas researchers first experimented with cultured human breast cancer cells in a solution containing nanoshells and then turned to tumors in mice. In both cases, temperatures inside the tumors reached levels high enough to damage cells within 4 to 6 minutes, killing the tumors but leaving surrounding tissue unharmed.

Battle Against Cancer This process causes the temperature of the cancer cell to increase 20°C to 35°C or 68°F to 95°F after 4-6 minutes of laser light exposure, causing the cell to almost double in temperature! Nanoshells convert light to heat well enough that they can be used to heat up a space 1000 times larger than their size. The transferred heat is strong enough to destroy the cancer cell. Healthy cells then consume the dead cancer cells through phagocytosis. When the process is done, only healthy cells remain and there are no traces of cancer.

Benefits of nanoshell treatment over standard treatments The use of nanoshells to treat cancer has benefits over standard treatments today. Standard treatments such as chemotherapy, radiation therapy, and surgery are used to destroy cancers cells. These treatments destroy cancer cells, but also many healthy cells in the process Due to their small size, nanoshells have the ability to only heat up the attached cancer cell. This allows them to target and destroy cancer cells while minimizing the amount of damage done to healthy cells.

Benefits of nanoshell treatment over standard treatments Nanoshells also provide a less intrusive treatment option than traditional methods. Once the nanoshells are injected into the blood stream and attach to the cancer cells, they are triggered from outside the body without any cutting or harmful radiation. The NIR light can pass harmlessly through most of the body and only interact with the nanoshells, causing them to heat up and destroy the cells they have attached to.