Using single-beam optical tweezers for the passive microrheology of complex fluids
Using single-beam optical tweezers for the passive microrheology of complex fluids
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DOI：
10.1117/12.2318019
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发表时间：
2018-09
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影响因子：
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通讯作者：
I. Stoev;A. Caciagli;Zhongyang Xing;E. Eiser
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文献类型：
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作者：
I. Stoev;A. Caciagli;Zhongyang Xing;E. Eiser
新型粘弹性材料的完整物理表征的一个重要方面是评估它们在短时间尺度上的响应。配备快速四分之一光电二极管的光镊通过提供关于样品的高频粘弹性信息来帮助完成这项任务。在被动微观流变学中，这通常通过从嵌入测试流体中的光学捕获珠的热运动中提取流变信息来实现。在这里，我们提出了校准和使用光镊研究热可逆DNA水凝胶的形成。我们补充我们的研究结果与流变数据从动态光散射，视频显微镜和传统的散装流变学。合并不同技术的实验数据，使我们能够研究这些DNA网络的粘弹性行为在一个很宽的频带和缩放的复杂的粘弹性模量在两个极端的频率。通过分析我们的瞬态网络的高频行为，我们证明了DNA的半柔性聚合物的性质，并提供了其持久性长度的估计。
One important aspect of the complete physical characterization of novel viscoelastic materials is the assessment of their response on short timescales. Optical tweezers, equipped with a fast quadrant photodiode, aid in fulfilling this task by providing high-frequency viscoelastic information about the sample. In passive microrheology, this is normally achieved by extracting rheological information from the thermal motion of an optically trapped bead embedded in a test fluid. Here we present the calibration and use of optical tweezers to study the formation of thermally reversible DNA hydrogels. We complement our results with rheological data from dynamic light scattering, video microscopy and conventional bulk rheology. Merging experimental data from different techniques allows us to study the viscoelastic behavior of these DNA networks over a wide frequency-band and the scaling of the complex viscoelastic modulus at the two frequency extremes. By analyzing the high-frequency behavior of our transient network, we prove the semi-flexible polymer nature of DNA and provide an estimate of its persistence length.