利用近红外扩散相关谱同时测量生物样品光学特性和动态特性

由于近红外光对于大多数生物样品具有较高的穿透深度,因此近红外光谱技术广泛用于生物医学、化工、食品安全以及农产品等领域的无损检测,但是多局限于生物样品的光学性质测量,即光吸收测量.利用最新研制的近红外光扩散相关谱系统和采用脂肪乳作为生物样品的替代物,同时测量了国产30%脂肪乳的光学特性和动态特性,约化散射系数约为303 cm~(-1),吸收系数约为0. 037 cm~(-1),30%脂肪乳稀释为0. 85%(体积比)浓度后的布朗扩散系数约为8. 40×10~(-9)cm~2/s,根据Stokes-Einstein关系可推算出脂肪乳的颗粒半径约为253 nm;研究了脂肪乳随时间演化特性,在七天时间内约化散射系数上升106%,布朗扩散系数下降到63%,研究表明利用近红外扩散相关谱系统的光强衰减可以获得生物样品的光学特性(约化散射系数和吸收系数),利用光强随时间的波动可以获得生物样品的动态特性(布朗扩散系数),因此能够更加准确的测量生物样品的性质变化,为生物样品检测提供一种新的技术手段.

The optical properties and dynamical property of biological sample determined simultaneously by diffuse correlation spectroscopy

Near-infrared spectroscopy is a promising method to monitor the characteristics of biological samples noninvasively in biomedical field, food safety field, agricultural field, etc. But most study focus on the measurement of optical properties of biological samples in these fields. Utilizing the latest developed diffuse correlation spectroscopy device and 30% intralipid as the phantom of biological sample, we demonstrated how to obtain both the optical property and dynamical property of 30% intralipid. The absorption coefficient and reduced scattering coefficient of 30% intralipid are 0.037cm-1 and 303 cm-1 respectively. The Brownian diffusion coefficient of the diluted 30%intralipid (0.85%, volume/volume) is 8.40×10-9cm2/s and the radius of intralipid particle is about 253nm deduced by Stokes-Einstein relation. The stability of the diluted 30% intralipid is also studied. The scattering coefficient increases by 106% and the Brownian diffusion coefficient decreases by 63% for seven days. This study suggest that diffuse correlation spectroscopy can not only measure the optical properties but also measure the dynamical property of biological sample, which may be a powerful tool in biomedical field, food safety field , agricultural field, etc.