Abstract Optical imaging represents one of the most essential tools in biological studies. Although with great advances, bio-optical imaging still suffers from problems such as resolution, sensitivity, speed, and penetration depth. Due to the unique optical properties of gold nanoparticles (AuNPs), i.e., surface plasmon resonance, AuNPs can be readily used to enhance optical imaging based on their absorption, scattering, fluorescence, Raman scattering, etc. Here, we include the most recent achievements and challenges associated with using AuNPs to improve resolution and sensitivity in biological imaging in vitro and in vivo. The application of AuNPs in the following three aspects were discussed: 1) Direct visualization of AuNPs inside the biosystems using i) dark field (DF) microscopy, ii) differential interference contrast (DIC) microscopy, and iii) other techniques, such as interferometric scattering (iSCAT) microscopy and photothermal imaging. Additionally, since orientation and rotational motions are closely related to various biological processes, we also summarized the recent advances of optical imaging methods in the rotational and orientation tracking of AuNPs. 2) Monitoring of biomolecular events and physiological processes using i) surface-enhanced Raman spectroscopy (SERS) and ii) plasmon enhanced fluorescence (PEF) for ultra-sensitive detection of biomolecules, including proteins, metabolites, DNA, RNA, etc. 3) In vivo deep tissue imaging using i) two-photon and/or multi-photon imaging, ii) optical coherence tomography (OCT), and iii) photoacoustic (PA) imaging for disease diagnoses, such as detecting tumors and other diseases in eye, brain, and bone. In conclusion, based on our literature study, AuNPs-assisted bioimaging acts as a promising tool in exploring fundamental biological questions and early diagnosis of diseases.

中文翻译：

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生物光学成像中的金纳米粒子

摘要 光学成像是生物学研究中最重要的工具之一。尽管有了很大的进步，生物光学成像仍然存在分辨率、灵敏度、速度和穿透深度等问题。由于金纳米粒子 (AuNPs) 独特的光学特性，即表面等离子体共振，AuNPs 可以很容易地用于基于其吸收、散射、荧光、拉曼散射等增强光学成像。在这里，我们包括最新的成就以及与使用 AuNP 提高体外和体内生物成像分辨率和灵敏度相关的挑战。讨论了 AuNPs 在以下三个方面的应用：1) 使用 i) 暗场 (DF) 显微镜，ii) 微分干涉对比 (DIC) 显微镜直接可视化生物系统内的 AuNP，iii) 其他技术，例如干涉散射 (iSCAT) 显微镜和光热成像。此外，由于方向和旋转运动与各种生物过程密切相关，我们还总结了光学成像方法在 AuNPs 旋转和方向跟踪方面的最新进展。2) 使用 i) 表面增强拉曼光谱 (SERS) 和 ii) 等离子体增强荧光 (PEF) 对生物分子（包括蛋白质、代谢物、DNA、RNA 等）进行超灵敏检测来监测生物分子事件和生理过程。 3)体内深层组织成像使用 i) 双光子和/或多光子成像，ii) 光学相干断层扫描 (OCT)，和 iii) 用于疾病诊断的光声 (PA) 成像，例如检测眼睛中的肿瘤和其他疾病，大脑和骨头。综上所述，