Download or read book Nanoscale Physical Enhancement by Gold Nanoparticles Under X-ray Irradiation written by Arjun Sharmah and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Radiation therapy using X-rays is one of the standard methods of treating cancer. There are numerous studies on examining the use of metallic nanoparticles for cancer therapy ranging from effective enhancement of radiation to targeted drug delivery. However, when it comes to elucidating the mechanism of enhancement of radiation in presence of nanoparticles, although there is a substantial literature on theoretical studies, only a limited experimental work has been done. Elucidating the mechanism can aid in designing optimum nanostructures so as to maximize the enhancement effect which can have far-reaching impact on lowering the dose used in radiation therapy without lowering the effect of the radiation and may even increase its efficacy. Extra electrons released by nanoparticles under X-ray irradiation leads to enhanced electron energy deposition which we call Physical Enhancement (PE) and identify two processes contributing to the PE - firstly, a nanoscale enhancement (T2PE) which occurs near the metal nanoparticle surface and secondly the average PE (T1PE). To probe the nanoscale physical enhancement we have devised a nanostructure made of liposome coated with calcium phosphate and encapsulating a dye based probe (Sulforhodamine-B), we call it CaPEL. CaPEL is mixed with gold nanoparticles and irradiated under hard X-rays. We observed a 2.1 fold enhancement for 0.25 weight percent (wp) of gold, which is equivalent to an enhancement of 42 wp−1 of Au. This enhancement is much higher than the generally accepted average PE of about 1 fold enhancement wp-1 of gold and can only be explained by T2PE. A theoretical calculation was done which supports the experimentally observed enhancement for one gold nanoparticle associated with one CaPEL. A sudden jump in enhancement is observed at around 0.25 wp of gold which is explained by a threshold gold concentration required to achieve a dynamic one-gold -to -one CaPEL association. After the initial jump the enhancement follows a general slope (1 wp−1 of Au) of the average PE, which is further proof of distinct T2PE (separate from average PE) and one-gold-to-one CaPEL association. This phenomenon is explained by Brownian Dynamics simulation. The CaPEL used in the experiment is a robust non-leaky nano-container with an average internal diameter of 68 nm and 15 nm thick external calcium phosphate shell. This is the first experimental nanoscale enhancement measurement. The use of metal nanoparticles as radiation dose enhancers is much more efficient near its surface and use of nanostructures designed to harness T2PE will be able to deliver substantially greater enhancement at much lower gold concentration. This can have implications in cancer treatment in making radiation therapy much more efficient. The probe developed here may also be used for targeted drug delivery with slight modification.