Simultaneous Force and Darkfield Measurements Reveal Solvent-Dependent Axial Control of Optically Trapped Gold Nanoparticles
Simultaneous Force and Darkfield Measurements Reveal Solvent-Dependent Axial Control of Optically Trapped Gold Nanoparticles
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同时力和暗场测量揭示了光捕获金纳米颗粒的溶剂依赖性轴向控制
DOI：
10.1021/acs.jpclett.3c00088
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Kamenetska, Maria
中科院分区：
文献类型：
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作者：
Jackson, Daniel J.;Dawes, Brian A.;Kamenetska, Maria
使用光学镊子(OT)的单分子力谱能够实现对动态生物过程的纳米分辨率测量，但不能对合成分子机制进行测量。由二氧化硅或聚苯乙烯制成的标准OT探针与有机溶剂中的溶液相化学捕获或力检测吸收光谱不兼容。在这里，我们使用定制的OT和暗场仪器演示了金纳米颗粒在水和有机条件下的光学捕获，该仪器可以同时唯一地测量单个金纳米颗粒(Au NPs)的力和散射光谱。我们的工作表明，针对含水条件开发的标准捕获模型不能解释在不同介质中观察到的趋势。我们确定，较大的推力减缓了在高指数有机溶剂中捕获力的增加，并导致了粒子的轴向位移，这可以通过陷阱强度来控制。这项工作开发了一个新的模型框架，包括轴向力，用于理解光学陷阱中的纳米粒子动力学。这些结果建立了暗场OT和Au NPs的组合作为单分子和单粒子光谱实验的有效OT探针，并对NP的位置进行了三维纳米控制。
Single molecule force spectroscopy using optical tweezers (OT) has enabled nanoresolved measurements of dynamic biological processes but not of synthetic molecular mechanisms. Standard OT probes made from silica or polystyrene are incompatible with trapping in organic solvents for solution phase chemistry or with force-detected absorption spectroscopies. Here, we demonstrate optical trapping of gold nanoparticles in both aqueous and organic conditions using a custom OT and darkfield instrument which can uniquely measure force and scattering spectra of single gold nanoparticles (Au NPs) simultaneously. Our work reveals that standard models of trapping developed for aqueous conditions cannot account for the trends observed in different media here. We determine that higher pushing forces mitigate the increase in trapping force in higher index organic solvents and lead to axial displacement of the particle which can be controlled through trap intensity. This work develops a new model framework incorporating axial forces for understanding nanoparticle dynamics in an optical trap. These results establish the combined darkfield OT with Au NPs as an effective OT probe for single molecule and single particle spectroscopy experiments, with three-dimensional nanoscale control over NP location.