Gyromagnetic Imaging: Dynamic Optical Contrast Using Gold Nanostars with Magnetic Cores

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• 作者：Qingshan Wei ; Hyon-Min Song ; Alexei P. Leonov ; Jacob A. Hale ; Dongmyung Oh ; Quy K. Ong ; Kenneth Ritchie ; Alexander Wei
• 刊名：Journal of the American Chemical Society
• 出版年：2009
• 出版时间：July 22, 2009
• 年：2009
• 卷：131
• 期：28
• 页码：9728-9734
• 全文大小：446K
• 年卷期：v.131,no.28(July 22, 2009)
• ISSN：1520-5126

文摘

Plasmon-resonant nanoparticles with optical scattering in the near-infrared (NIR) are valuable contrast agents for biophotonic imaging and may be detected at the single-particle limit against a dark background, but their contrast is often limited in environments with high noise. Here we consider gyromagnetic imaging as a dynamic mode of optical contrast, using gold nanostars with superparamagnetic cores. The nanostars exhibit polarization-sensitive NIR scattering and can produce a frequency-modulated signal in response to a rotating magnetic field gradient. This periodic “twinkling” can be converted into Fourier-domain images with a dramatic reduction in background. We demonstrate gyromagnetic imaging of nanostars inside of tumor cells, using broadband excitation: while their time-domain signals are obscured by incoherent scattering, their Fourier-domain signals can be clearly resolved in less than a second. The gyromagnetically active nanostars do not cause a loss in viability, and can even have a mild stimulatory effect on cell growth.