National Research Council, Institute of Clinical Physiology, Lecce, Italy.
Int J Nanomedicine. 2012;7:4373-89. doi: 10.2147/IJN.S33908. Epub 2012 Aug 9.
To evaluate the diagnostic performance of gold nanorod (GNR)-enhanced optoacoustic imaging employing a conventional echographic device and to determine the most effective operative configuration in order to assure optoacoustic effectiveness, nanoparticle stability, and imaging procedure safety.
The most suitable laser parameters were experimentally determined in order to assure nanoparticle stability during the optoacoustic imaging procedures. The selected configuration was then applied to a novel tissue-mimicking phantom, in which GNR solutions covering a wide range of low concentrations (25-200 pM) and different sample volumes (50-200 μL) were exposed to pulsed laser irradiation. GNR-emitted optoacoustic signals were acquired either by a couple of single-element ultrasound probes or by an echographic transducer. Off-line analysis included: (a) quantitative evaluation of the relationships between GNR concentration, sample volume, phantom geometry, and amplitude of optoacoustic signals propagating along different directions; (b) echographic detection of "optoacoustic spots," analyzing their intensity, spatial distribution, and clinical exploitability. MTT measurements performed on two different cell lines were also used to quantify biocompatibility of the synthesized GNRs in the adopted doses.
Laser irradiation at 30 mJ/cm(2) for 20 seconds resulted in the best compromise among the requirements of effectiveness, safety, and nanoparticle stability. Amplitude of GNR-emitted optoacoustic pulses was proportional to both sample volume and concentration along each considered propagation direction for all the tested boundary conditions, providing an experimental confirmation of isotropic optoacoustic emission. Average intensity of echographically detected spots showed similar behavior, emphasizing the presence of an "ideal" GNR concentration (100 pM) that optimized optoacoustic effectiveness. The tested GNRs also exhibited high biocompatibility over the entire considered concentration range.
An optimal configuration for GNR-enhanced optoacoustic imaging was experimentally determined, demonstrating in particular its feasibility with a conventional echographic device. The proposed approach can be easily extended to quantitative performance evaluation of different contrast agents for optoacoustic imaging.
评估采用常规超声设备的金纳米棒（GNR）增强光声成像的诊断性能，并确定最有效的操作配置，以确保光声效果、纳米颗粒稳定性和成像过程的安全性。
实验确定了最适合的激光参数，以确保光声成像过程中纳米颗粒的稳定性。然后将选定的配置应用于新型组织模拟体模中，其中将覆盖广泛低浓度（25-200 pM）和不同样品体积（50-200 μL）的 GNR 溶液暴露于脉冲激光辐射下。通过一对单元素超声探头或超声换能器采集 GNR 发射的光声信号。离线分析包括：（a）定量评估 GNR 浓度、样品体积、体模几何形状和沿不同方向传播的光声信号幅度之间的关系；（b）对“光声斑点”进行超声检测，分析其强度、空间分布和临床可操作性。还对两种不同细胞系进行了 MTT 测量，以量化所采用剂量下合成的 GNR 的生物相容性。
激光辐照 30 mJ/cm(2)20 秒，在效果、安全性和纳米颗粒稳定性的要求之间取得了最佳折衷。在所测试的边界条件下，对于每个考虑的传播方向，GNR 发射的光声脉冲的幅度均与样品体积和浓度成正比，为各向同性光声发射提供了实验验证。超声检测到的斑点的平均强度也表现出类似的行为，强调了存在优化光声效果的“理想”GNR 浓度（100 pM）。所测试的 GNR 在整个考虑的浓度范围内也表现出很高的生物相容性。
实验确定了 GNR 增强光声成像的最佳配置，特别是证明了其使用常规超声设备的可行性。所提出的方法可以很容易地扩展到光声成像不同对比剂的定量性能评估。
