Membrane Tension Modifies Redox Loading and Release in Single Liposome Electroanalysis
Membrane Tension Modifies Redox Loading and Release in Single Liposome Electroanalysis
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DOI：
10.1021/acs.analchem.0c04536
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发表时间：
2021-02-17
影响因子：
7.4
通讯作者：
Zhang, Bo
中科院分区：
文献类型：
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作者：
Barlow, Samuel T.;Figueroa, Benjamin;Zhang, Bo
在这里，我们提出了一个研究脂质体如何加载和释放其内容在其电化学检测。我们加载200 nm的脂质体与氧化还原介体，亚铁氰化物，并使用安培法检测它们的碰撞碳纤维微电极（CFE）。我们发现，我们可以通过改变脂质体悬浮的缓冲液的渗透压来控制它们的电穿孔过程的稳定性和亚铁氰化物的释放量。有趣的是，我们观察到，释放的亚铁氰化物的量变化显着与缓冲液渗透压在一个非单调的方式。使用受激拉曼散射（SRS），我们证实，这种行为的部分原因是在响应于渗透压的囊内氧化还原浓度的波动。令我们惊讶的是，从SRS获得的氧化还原浓度远大于从电流法获得的，这意味着脂质体在电穿孔过程中可能仅释放其内容物的一小部分。与这一假设一致，我们观察到远远超过泊松统计预测的频率的电化学信号的弹幕，表明单个脂质体可以与CFE碰撞并电穿孔多次。通过这项研究，我们已经解决了一些悬而未决的问题，围绕电化学检测的脂质体，同时延长观察从巨大的单层囊泡到200 nm的脂质体具有高的时间分辨率和灵敏度。
Here, we present a study of how liposomes are loaded and release their contents during their electrochemical detection. We loaded 200 nm liposomes with a redox mediator, ferrocyanide, and used amperometry to detect their collision on a carbon-fiber microelectrode (CFE). We found that we could control the favorability of their electroporation process and the amount of ferrocyanide released by modifying the osmolarity of the buffer in which the liposomes were suspended. Interestingly, we observed that the quantity of the released ferrocyanide varied significantly with buffer osmolarity in a nonmonotonic fashion. Using stimulated Raman scattering (SRS), we confirmed that this behavior was partly explained by fluctuations in the intravesicular redox concentration in response to osmotic pressure. To our surprise, the redox concentration obtained from SRS was much greater than that obtained from amperometry, implying that liposomes may release only a fraction of their contents during electroporation. Consistent with this hypothesis, we observed barrages of electrochemical signals that far exceeded the frequency predicted by Poisson statistics, suggesting that single liposomes can collide with the CFE and electroporate multiple times. With this study, we have resolved some outstanding questions surrounding electrochemical detection of liposomes while extending observations from giant unilamellar vesicles to 200 nm liposomes with high temporal resolution and sensitivity.