ESPCI ParisTech, PSL Research University, CNRS, INSERM, Université Pierre et Marie Curie, Institut Langevin, 1 rue Jussieu, 75005 Paris, France.
Photoacoustics. 2014 Dec 30;3(1):20-5. doi: 10.1016/j.pacs.2014.12.002. eCollection 2015 Mar.
In this work, we experimentally investigate thermal-based nonlinear photoacoustic generation as a mean to discriminate between different types of absorbing particles. The photoacoustic generation from solutions of dye molecules and gold nanospheres (same optical densities) was detected using a high frequency ultrasound transducer (20 MHz). Photoacoustic emission was observed with gold nanospheres at low fluence for an equilibrium temperature around 4 °C, where the linear photoacoustic effect in water vanishes, highlighting the nonlinear emission from the solution of nanospheres. The photoacoustic amplitude was also studied as a function of the equilibrium temperature from 2 °C to 20 °C. While the photoacoustic amplitude from the dye molecules vanished around 4 °C, the photoacoustic amplitude from the gold nanospheres remained significant over the whole temperature range. Our preliminary results suggest that in the context of high frequency photoacoustic imaging, nanoparticles may be discriminated from molecular absorbers based on nanoscale temperature rises.
在这项工作中，我们通过实验研究了基于热的非线性光声产生，以区分不同类型的吸收颗粒。使用高频超声换能器（20 MHz）检测染料分子和金纳米球（相同光密度）溶液中的光声产生。在低辐照下观察到金纳米球的光声发射，平衡温度约为 4°C，此时水中的线性光声效应消失，突出了纳米球溶液的非线性发射。还研究了光声幅度作为平衡温度从 2°C 到 20°C 的函数。虽然染料分子的光声幅度在 4°C 左右消失，但金纳米球的光声幅度在整个温度范围内仍然显著。我们的初步结果表明，在高频光声成像的情况下，基于纳米级温升，可能可以将纳米颗粒与分子吸收剂区分开来。
