To solve the problem that analyte molecules cannot easily enter “hot spots” on a conventional solid SERS substrate, we developed a mixing-assisted “hot spots” occupying (MAHSO) SERS strategy to improve utilization of “hot spots”. Compared with the conventional substrate, the MAHSO substrate enhances the sensitivity of SERS measurement by thousands of times. The MAHSO substrate possesses excellent properties of high enhancement, high uniformity, and long-term stability because the MAHSO substrate is integrated inside an ultrafast microfluidic mixer. The mixer makes analytes and metal colloid homogeneously mixed, and analytes are naturally located in “hot spots”, the gaps between adjacent NPs, during the process that NPs deposit on the channel wall. As a multi-inlet device, the MAHSO chip offers a convenient in situ method to study environmental effects on analytes or molecular interactions by flexibly regulating fluid in microchannels and monitoring responses of analytes by SERS spectra. Because all experiments are conducted in aqueous environments, which is similar to the physiological conditions, the MAHSO chip is especially suitable to be applied to study biomolecules. Using this strategy, different conformational changes of the wild type and mutant G150D of protein PMP22-TM4 depending on environmental pH have been observed in situ and analyzed. As a lab-on-a-chip (LoC) device, the MAHSO SERS chip will benefit the field of molecular dynamics, as well as molecule–molecule or molecule–surface interactions in the future.

中文翻译：

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混合辅助“热点”占据SERS策略进行高度敏感的原位研究

为了解决分析物分子无法轻易进入常规固态SERS基板上的“热点”的问题，我们开发了一种混合辅助的“热点”占据（MAHSO）SERS策略，以提高“热点”的利用率。与常规基板相比，MAHSO基板将SERS测量的灵敏度提高了数千倍。由于MAHSO基质集成在超快微流混合器中，因此MAHSO基质具有出色的高增强，高均匀性和长期稳定性。混合器使分析物和金属胶体均匀混合，并且在NP沉积在通道壁上的过程中，分析物自然位于“热点”（相邻NP之间的间隙）中。作为多入口设备，MAHSO芯片通过灵活调节微通道中的流体并通过SERS光谱监测分析物的响应，提供了一种方便的原位方法来研究环境对分析物或分子相互作用的影响。由于所有实验都是在类似于生理条件的水性环境中进行的，因此MAHSO芯片特别适合用于研究生物分子。使用这种策略，原位观察并分析了取决于环境pH的蛋白PMP22-TM4野生型和突变体G150D的不同构象变化。作为芯片实验室（LoC）的设备，MAHSO SERS芯片将在未来的分子动力学以及分子与分子或分子与表面之间的相互作用领域中受益。