Sensitive Determination of Concentration of Nonfluorescent Species in an Extended-Nano Channel by Differential Interference Contrast Thermal Lens Microscope
Sensitive Determination of Concentration of Nonfluorescent Species in an Extended-Nano Channel by Differential Interference Contrast Thermal Lens Microscope
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DOI：
10.1021/ac1017088
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发表时间：
2010-09-01
影响因子：
7.4
通讯作者：
Kitamori, Takehiko
中科院分区：
文献类型：
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作者：
Shimizu, Hisashi;Mawatari, Kazuma;Kitamori, Takehiko
采用微分干涉对比热透镜显微镜（DIC-TLM）光热检测器测定纳米通道中非荧光溶液的浓度。这种方法利用由光吸收引起的溶液折射率的局部变化。通过压力驱动的纳米流体控制系统将溶液引入100 nm尺度的通道中，并通过DIC-TLM测定其浓度。在宽21 μ M、深500 nm的纳米通道中，检测限为2.4 μ M。LOD比常规方法小3个数量级。此外，通过使用光程长度为500 nm的纳米通道，精确地确定了检测体积仅为0.25 fL。根据这些结果，计算出检测到的分子数为390。此外，还可以测定790nm宽，500nm深的纳米通道中溶液的浓度。最后，研究了灵敏度与通道尺寸之间的关系，发现灵敏度随着纳米通道尺寸的减小而减小，这表明水和二氧化硅的折射率变化相互抵消。在不需要任何特殊的制造技术的情况下，DIC-TLM实现了对纳米通道中非荧光物质的灵敏检测。因此，DIC-TLM有望成为一种非常有用的纳米流体分析技术。
A photothermal detector, named differential interference contrast thermal lens microscope (DIC-TLM), was used to determine the concentration of a nonfluorescent solution in a nanochannel. This method exploits a local change in the refractive index of a solution caused by light absorption. A solution was introduced into a 100-nm scale channel by a pressure-driven nanofluidic control system and its concentration was determined by DIC-TLM. The limit of detection (LOD) was 2.4 mu M in a nanochannel that was 21 mu m wide and 500 nm deep. The LOD was 3 orders of magnitude smaller than that of conventional method. Moreover, the detection volume was accurately determined to be merely 0.25 fL by using a nanochannel with an optical path length of 500 nm. Based on these results, the number of detected molecules was calculated to be 390. In addition, the concentration of a solution in a nanochannel that was 790 nm wide and 500 nm deep could be determined. Finally, the relationship between sensitivity and channel size was investigated and the sensitivity was found to decrease with decreasing nanochannel size, which indicates that the changes in the refractive indices of water and silica cancel each other out. The DIC-TLM realizes sensitive detection of nonfluorescent species in nanochannels without requiring any special fabrication techniques. Therefore, DIC-TLM is expected to be a highly useful analytical technique in nanofluidics.