Institute of Biomedical Engineering, National Cheng Kung University, Tainan, 701 Taiwan, ROC.
Biomed Eng Online. 2010 Feb 25;9:12. doi: 10.1186/1475-925X-9-12.
Intrinsic optical signals (IOS), which reflect changes in transmittance and scattering light, have been applied to characterize the physiological conditions of target biological tissues. Backscattering approaches allow mounting of the source and detector on the same side of a sample which creates a more compact physical layout of device. This study presents a compact backscattering design using fiber-optic guided near-infrared (NIR) light to measure the amplitude and phase changes of IOS under different osmotic challenges.
High-frequency intensity-modulated light was guided via optic fiber, which was controlled by micromanipulator to closely aim at a minimum cluster of cortical neurons. Several factors including the probe design, wavelength selection, optimal measuring distance between the fiber-optical probe and cells were considered. Our experimental setup was tested in cultured cells to observe the relationship between the changes in backscattered NIR light and cellular IOS, which is believed mainly caused by cell volume changes in hypo/hyperosmotic solutions (+/- 20, +/- 40 and +/- 60 mOsm).
The critical parameters of the current setup including the optimal measuring distance from fiber-optical probe to target tissue and the linear relationship between backscattering intensity and cell volume were determined. The backscattering intensity was found to be inversely proportional to osmotic changes. However, the phase shift exhibited a nonlinear feature and reached a plateau at hyperosmotic solution.
Our study indicated that the backscattering NIR light guided by fiber-optical probe makes it a potential alternative for continuous observation of intrinsic optical properties of cell culture under varied physical or chemical challenges.
固有光学信号（IOS）反映了透光率和散射光的变化，已被用于描述目标生物组织的生理状态。背散射方法允许将光源和探测器安装在样品的同一侧，从而形成更紧凑的设备物理布局。本研究提出了一种使用光纤引导近红外（NIR）光的紧凑背散射设计，用于测量在不同渗透挑战下 IOS 的幅度和相位变化。
高频强度调制光通过光纤引导，由微操纵器控制，以紧密瞄准最小的皮质神经元簇。考虑了包括探头设计、波长选择、光纤探头与细胞之间最佳测量距离在内的几个因素。我们的实验装置在培养细胞中进行了测试，以观察背散射近红外光与细胞 IOS 之间的变化关系，据信这主要是由低渗/高渗溶液（+/-20、+/-40 和 +/-60 mOsm）中细胞体积变化引起的。
确定了当前设置的关键参数，包括光纤探头到目标组织的最佳测量距离以及背散射强度与细胞体积之间的线性关系。发现背散射强度与渗透压变化成反比。然而，相位偏移表现出非线性特征，并在高渗溶液中达到平台期。
我们的研究表明，光纤引导的背散射近红外光为在不同物理或化学挑战下连续观察细胞培养的固有光学特性提供了一种潜在的替代方法。
