Photothermal therapy of cancer with gold nanoparticles

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One nanometer is a billionth of a meter and nanotechnology is the engineering of functional systems at nanoscale or in other words at molecular level which gives precision and accuracy in their design and function. Nanotechnology has potential to revolutionize each and every filed of science and technology. In the field of biomedical research, it will change the basis for cancer diagnosis and treatment. Cancer is a group of diseases identified asuncontrolled cell division and resulting in the masses of tissues called tumors.


There are different types of tumors, caused by exterior factors like chemicals, radiations, viruses etc. Cancer is also caused by internal factors like hormones, immune conditions and genetic alteration. There are several different types of cancerstherapies such ashyperthermia, chemotherapy, radiotherapy and immunotherapy. Hyperthermia treatment of cancer involves heating of the tumor at 42°C. At this temperature the cancerous cells are destroyed but normal body cells. It is a physical treatment of cancer which has lesser side effects than chemotherapy. Nanoparticles based hyperthermia is attained by using metal nanoparticles that change electromagnetic energy into heat. Gold nanoparticles are emerging as promising agent for cancer therapy.


Noble metal nanoparticles such as of gold are concentrated only within the tumor cells because of their open texture and vasculature but not in the normal cells which allow the selective heating of the cancer cells upon irradiation with infrared radiation. Use of these nanoparticles in cancer therapy decreases the side effects of the cancer therapy, as well as enhances the delivery and efficacy of therapeutic agents. Gold nanoparticles are effective in cancer therapy because of their unique photo physical and chemical properties.


When gold nano particles are exposed to near infrared radiation (NIR) their surface electrons oscillate, due to this oscillations change in size and shape of their surface electroniccloud takes place which results in the absorption of radiation and the phenomenon is known as Surface Plasmon Resonance (SPR). Electrons are excited by absorbing the near infra-red light and then revert back to their ground state and energy is released in the form of heat. This heat destroys the cancerous tissues surrounding the gold nanoparticles. The desired wavelength would be 700-1000 nm because the biological tissues are optically transparent at this wavelength.


There is another kind of nanoparticles based hyperthermia treatment of cancer called magnetic hyperthermia in which magnetic nanoparticles are used. In magnetic hyperthermia, heat is generated by when magnetic nanoparticles within the cells are exposed to oscillating external magnetic field. The heat is produced by two mechanisms Brownian modes i.e. heat from the friction produced by total particles oscillation or by Neel modes i.e. heat from the spinning of magnetic moment with each field oscillation. When cancer cells arecarefully exposed to energy, it allows the control and adjustable heating to reach the therapeutic temperature. If we localized the targeted nanoparticles close to cancer cells then harmful effect to surrounding tissues is minimized. In the last 150 years many techniques have been studied in order to treat the cancer but all of these have many side effects significantly deteriorating the health of patient.


There have been significant improvement in cancer treatment due to nanotechnology; we can early identify, prevent, and treat the disease with high degree of accuracy.The efficiency of the nanoparticles based hyperthermia treatment of cancer can be affectively increased by simultaneous incorporation of these nanoparticles with some targeting as well as chemotherapeutic agents. The nanotechnology is playing a vital role in developing the modern tools and techniques for early diagnosis and effective treatment of cancer and nanoparticles based hyperthermia is one of them.


The authors are associated with the Department of Chemistry, University of Agriculture Faisalabad, Punjab, Pakistan.


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Published in: Volume 07 Issue 15

Short Link: http://www.technologytimes.pk/?p=15607