Yu Zhipeng, Huangfu Jiangtao, Zhao Fangyuan, Xia Meiyun, Wu Xi, Niu Xufeng, Li Deyu, Lai Puxiang, Wang Daifa
Department of Biomedical Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
Shenzhen Research Institute, The Hong Kong Polytechnic University, Shenzhen, 518057, China.
Sci Rep. 2018 Feb 13;8(1):2927. doi: 10.1038/s41598-018-21258-4.
Manipulating and focusing light deep inside biological tissue and tissue-like complex media has been desired for long yet considered challenging. One feasible strategy is through optical wavefront engineering, where the optical scattering-induced phase distortions are time reversed or pre-compensated so that photons travel along different optical paths interfere constructively at the targeted position within a scattering medium. To define the targeted position, an internal guidestar is needed to guide or provide a feedback for wavefront engineering. It could be injected or embedded probes such as fluorescence or nonlinear microspheres, ultrasonic modulation, as well as absorption perturbation. Here we propose to use a magnetically controlled optical absorbing microsphere as the internal guidestar. Using a digital optical phase conjugation system, we obtained sharp optical focusing within scattering media through time-reversing the scattered light perturbed by the magnetic microsphere. Since the object is magnetically controlled, dynamic optical focusing is allowed with a relatively large field-of-view by scanning the magnetic field externally. Moreover, the magnetic microsphere can be packaged with an organic membrane, using biological or chemical means to serve as a carrier. Therefore, the technique may find particular applications for enhanced targeted drug delivery, and imaging and photoablation of angiogenic vessels in tumours.
长期以来，人们一直希望能在生物组织和类似组织的复杂介质内部对光进行操控和聚焦，但这被认为具有挑战性。一种可行的策略是通过光波前工程，在该工程中，光散射引起的相位畸变被时间反转或预补偿，从而使沿不同光路传播的光子在散射介质内的目标位置相长干涉。为了定义目标位置，需要一个内部引导星来引导或为波前工程提供反馈。它可以是注入或嵌入的探针，如荧光或非线性微球、超声调制以及吸收扰动。在此，我们提议使用磁控光吸收微球作为内部引导星。利用数字光学相位共轭系统，我们通过对由磁性微球扰动的散射光进行时间反转，在散射介质内实现了尖锐的光学聚焦。由于该物体是磁控的，通过外部扫描磁场，可以在相对较大的视场内实现动态光学聚焦。此外，磁性微球可以用有机膜包裹，利用生物或化学手段作为载体。因此，该技术可能在增强靶向药物递送以及肿瘤血管生成血管的成像和光消融方面找到特殊应用。
