Depth of photothermal conversion of gold nanorods embedded in a tissue-like phantom

Gold nanorod (AuNR)-assisted photothermal therapy has emerged as a viable method for selective killing of cancer cells and shows promise for tumor destruction in vivo. This study examined the distribution of AuNR conversion expected to occur during photothermal therapy in vivo. Tissue-like phantoms were prepared with polyethylene glycol AuNRs distributed homogeneously at a concentration representative of a systemic injection. Phantoms were illuminated with a nanosecond pulsed laser (800 nm) at a variety of combinations of pulse energy (12-120 mJ) and pulse count (1-1000). Operating at the American National Standards Institute safety limit for human skin exposure (30 mJ cm(-2)), a diameter of 13 mm and a depth of 7.6 mm of AuNR conversion were observed in the gel phantoms after 1000 laser pulses (100 s exposure). Significant AuNR conversion was measured to a depth of 6 mm after only 100 pulses. Comparison of the measured AuNR conversion distribution with Monte Carlo simulation suggested that the fluence threshold for AuNR conversion estimated from phantom measurements was in the range of 20-43 mJ cm(-2). The results suggest that AuNR-assisted photothermal therapy will be effective for tumors within 10 mm of the illuminated tissue surface.

金纳米棒（AuNR）辅助的光热疗法已成为一种选择性杀伤癌细胞的可行方法，并在体内肿瘤破坏方面显示出潜力。本研究检测了在体内光热疗法过程中预期发生的金纳米棒转化的分布情况。制备了组织模拟体模，其中聚乙二醇金纳米棒以代表全身注射的浓度均匀分布。用纳秒脉冲激光（800nm）在多种脉冲能量（12 - 120mJ）和脉冲次数（1 - 1000）组合下照射体模。在按照美国国家标准协会人体皮肤暴露安全限值（30mJ/cm²）操作时，在1000次激光脉冲（100秒照射）后，在凝胶体模中观察到直径为13mm、深度为7.6mm的金纳米棒转化。仅100次脉冲后，在6mm深度处就测量到显著的金纳米棒转化。将测量的金纳米棒转化分布与蒙特卡罗模拟进行比较表明，根据体模测量估计的金纳米棒转化的注量阈值在20 - 43mJ/cm²范围内。结果表明，金纳米棒辅助的光热疗法对于距照射组织表面10mm以内的肿瘤将是有效的。