State Key Laboratory of Modern Optical Instrumentation College of Optical Science and Engineering Zhejiang University Hangzhou 310027 China.
Department of Biomedical Engineering Boston University Boston MA 02215 USA.
Adv Sci (Weinh). 2021 Feb 8;8(9):2003136. doi: 10.1002/advs.202003136. eCollection 2021 May.
High-sensitivity chemical imaging offers a window to decipher the molecular orchestra inside a living system. Based on vibrational fingerprint signatures, coherent Raman scattering microscopy provides a label-free approach to map biomolecules and drug molecules inside a cell. Yet, by near-infrared (NIR) pulse excitation, the sensitivity is limited to millimolar concentration for endogenous biomolecules. Here, the imaging sensitivity of stimulated Raman scattering (SRS) is significantly boosted for retinoid molecules to 34 micromolar via electronic preresonance in the visible wavelength regime. Retinoids play critical roles in development, immunity, stem cell differentiation, and lipid metabolism. By visible preresonance SRS (VP-SRS) imaging, retinoid distribution in single embryonic neurons and mouse brain tissues is mapped, retinoid storage in chemoresistant pancreatic and ovarian cancers is revealed, and retinoids stored in protein network and lipid droplets of are identified. These results demonstrate VP-SRS microscopy as an ultrasensitive label-free chemical imaging tool and collectively open new opportunities of understanding the function of retinoids in biological systems.
高灵敏度化学成像是揭示活体内分子交响乐的一扇窗口。基于振动指纹特征，相干拉曼散射显微镜提供了一种无标记的方法来绘制细胞内的生物分子和药物分子。然而，通过近红外（NIR）脉冲激发，对于内源性生物分子，灵敏度仅限于毫摩尔浓度。在这里，通过在可见波长范围内的电子预共振，将类视黄醇分子的受激拉曼散射（SRS）的成像灵敏度显著提高到 34 微摩尔。类视黄醇在发育、免疫、干细胞分化和脂质代谢中起着关键作用。通过可见预共振 SRS（VP-SRS）成像，绘制了单个胚胎神经元和小鼠脑组织中的类视黄醇分布，揭示了化学抗性胰腺和卵巢癌中的类视黄醇储存，并鉴定了蛋白质网络和脂滴中的类视黄醇储存。这些结果表明 VP-SRS 显微镜是一种超灵敏的无标记化学成像工具，并共同为理解类视黄醇在生物系统中的功能开辟了新的机会。
