聚吡咯修饰的金纳米棒对肿瘤的光学相干层析成像的影响

摘要

聚吡咯（PPy）制备简单、生物相容性好，且在近红外（NIR）光谱范围内有很强的吸收，可作为一种良好的光热治疗试剂；同时，其NIR光吸收性质也可用于增强光学相干层析成像（OCT）的对比效果。因此，采用PPy对传统的OCT对比试剂———金纳米棒（GNR）进行表面修饰，有望获得对比效果更好且生物毒性较小的新型OCT对比试剂。选用吡咯为起始原料，在GNR表面进行一步简单的氧化聚合反应即可制备得到PPy修饰的金纳米棒（GNR‐PPy）。利用紫外‐可见吸收光谱，拉曼光谱和透射电子显微镜对制备的样品进行了分析和表征。构建小鼠荷瘤模型，以研究GNR‐PPy对肿瘤OCT图像对比度的增强效果。采用中心波长为840nm的OCT系统对注射了纳米粒子的肿瘤区域进行OCT成像。结果表明，肿瘤组织注射了GNR‐PPy后，OCT信号衰减非常明显；与注射了GNR的OCT图像相比，840nm光在GNR‐PPy的OCT图像中的穿透深度明显更低。从OCT图像中抽提出一维的衰减曲线对OCT图像进行定量分析，发现注射有GNR‐PPy肿瘤组织的OCT信号衰减系数明显高于注射了GNR的组织。表明，相对于GNR，GNR‐PPy具有更好的OCT信号对比效果，这在增强肿瘤成像效果方面具有潜在应用价值。%Polypyrrole (PPy) is easy‐prepared with good biocompatibility and strong absorption in near‐infrared (NIR) region which can serve as both the photothermal therapeutic agent and contrast agent of optical coherence tomography (OCT) imaging . Herein ,gold nanorod (GNR) modified with PPy (GNR‐PPy) as contrast agent for optical coherence tomography imaging was investigated .GNR‐PPy was synthesized via one‐pot facile oxidative polymerization by using pyrrole and GNR as starting materi‐als .Nanoparticles were characterized using ultraviolet‐visible absorbance spectroscopy ,Raman spectroscopy and transmission electron microscopy .A xenograft tumor mouse model was fabricated to study the OCT contrast effect of GNR‐PPy on breast tumor .An OCT system equipped with an 840 nm SLED was used for OCT imaging of the tumors injected with gold nanostruc‐tures .The experimental results indicated that the penetration depth of the OCT signals from tumors injected with GNR‐PPy was lower than that from tumors injected with gold nanorods ,which could be ascribed to the stronger light activity of GNR‐PPy in NIR region .To quantitatively analyze the contrast effect ,the attenuation coefficients were extracted from the OCT images of tumors injected with the nanostructures .In comparison with the attenuation coefficient extracted from the OCT images contai‐ning GNR ,the attenuation coefficient of tumors injected with GNR‐PPy was significant higher .It was concluded that gold nano‐rods modified with polypyrrole can enhance the light absorption in near‐infrared much better ,which would provide a possible de‐tection means for enhancing the contrast effect of tumor tissues .