School of Mechanical, Materials and Energy Engineering, Indian Institute of Technology Ropar, Rupnagar, Punjab, India.
Int J Hyperthermia. 2013;29(1):87-97. doi: 10.3109/02656736.2012.753162.
This study seeks to define parameters for gold nanorod assisted thermal therapy, to achieve the thermal ablation temperature (50-60°C) in the tumour region and spare healthy tissue surrounding the tumour. Also, a criterion for size selection of gold nanorods is described based on the role of optical coefficients.
In this study a tissue domain (comprising a 3 mm tumour and 7 mm of surrounding healthy tissue) embedded with gold nanorods is irradiated with electromagnetic radiation within the therapeutic wavelength band. Optical interaction is captured using light scattering theory (Mie-electrostatic approach). The resulting temperature field is evaluated using Penne's bioheat model. The effect of key parameters, namely irradiation intensity, irradiation duration and volume fraction, on tissue temperature is also modelled numerically.
With increasing nanorod diameter - from 5 nm to 15 nm - the scattering coefficient increases ∼76 times as compared to a 1.7-fold increase in absorption coefficient. Scattering is considerably minimised by having smaller gold nanorods of 5 nm diameter. For this study, gold nanorods of 5 nm diameter and volume fraction 0.001%, irradiated with 50 W/m(2)-nm for 250 s ablated the tumour as well as spare healthy tissue 2 mm beyond the tumour region.
Overall it may be concluded that tumour ablation as well as surrounding healthy tissue-sparing (within millimetres immediately adjacent to the tumour) can be achieved through a combination of specified parameters, namely diameter and volume fraction of gold nanorods, irradiation intensity and duration.
本研究旨在确定金纳米棒辅助热疗的参数，以实现肿瘤区域的热消融温度（50-60°C），同时保护肿瘤周围的健康组织。此外，还根据光学系数的作用描述了金纳米棒尺寸选择的标准。
在这项研究中，一个包含 3mm 肿瘤和 7mm 周围健康组织的组织域嵌入了金纳米棒，并在治疗波长带内用电磁辐射照射。使用光散射理论（Mie-静电方法）捕获光学相互作用。使用 Penne 生物热模型评估产生的温度场。还通过数值模拟研究了关键参数（即辐照强度、辐照持续时间和体积分数）对组织温度的影响。
随着纳米棒直径从 5nm 增加到 15nm，散射系数增加了约 76 倍，而吸收系数仅增加了 1.7 倍。通过使用直径为 5nm 的较小金纳米棒，可以大大减少散射。对于这项研究，直径为 5nm 且体积分数为 0.001%的金纳米棒在 50W/m(2)-nm 的辐照强度下辐照 250s 可以消融肿瘤以及肿瘤区域外 2mm 的健康组织。
总的来说，可以得出结论，通过指定参数（即金纳米棒的直径和体积分数、辐照强度和持续时间）的组合，可以实现肿瘤消融以及紧邻肿瘤的毫米级健康组织的保护。
