What Was Observed? (Introduction)

• Bioelectronics devices bridge the gap between biology and electronics to control biological systems using electronic signals.
• The potassium ion (K+) plays a crucial role in cell functions, including maintaining cell membrane potential (Vmem) and generating action potentials (electric signals in cells).
• This research presents two types of bioelectronic ion pumps that control K+ concentration for in vitro cell cultures, enabling precise control over cell behavior in laboratory settings.
• The study focuses on developing bioelectronic systems for controlling potassium ions in cell culture experiments to better understand their effects on cells, like THP-1 macrophages (a type of immune cell).

What is a Bioelectronic Ion Pump?

• A bioelectronic ion pump is a device that moves specific ions (like potassium ions) through a solution using an electric field generated by electronic signals.
• These pumps are used to simulate biological processes, allowing researchers to manipulate ion concentrations in controlled environments.
• Ion pumps have applications in various fields, including inflammation treatment, epilepsy management, cell differentiation, and wound healing.

What is Potassium’s Role in Cells?

• Potassium (K+) is essential for maintaining the balance of fluids and electrical charges inside and outside the cell.
• It helps maintain the membrane potential (Vmem), which is like a battery that powers the cell’s electrical functions.
• Potassium ions are crucial for nerve function, muscle contraction, and maintaining a healthy cardiovascular system.

How Do These Ion Pumps Work? (Device Overview)

• The first ion pump is a PDMS-based device that fits directly into a standard six-well cell culture plate.
• The device uses a voltage to move K+ ions from a reservoir to a target area where the ions are needed, helping researchers control the ion concentration for cell studies.
• The second ion pump is an advanced on-chip device with a high spatial resolution, allowing for precise delivery of K+ ions to specific spots in the cell culture.

How Was the Ion Pump Tested? (Results)

• The ion pumps were tested using a six-well cell culture plate under a fluorescence microscope to monitor real-time delivery of K+ ions.
• Fluorescent dyes, like ION Potassium Green-2 (IPG-2), were used to measure the changes in K+ concentration. The fluorescence intensity increased with higher K+ concentrations.
• The pump was actuated with alternating positive and negative voltages (1.5 V and -1.5 V), which pushed K+ ions in and out of the target area.
• The researchers recorded the current produced by the device during each voltage application to calculate how much K+ was delivered.
• The results showed that a higher applied voltage and higher KCl concentration in the reservoir resulted in more K+ being delivered to the target area.

How Does Spatial Resolution Work in the Ion Pump? (Advanced Pump Design)

• The advanced on-chip ion pump has a microchannel array with 100 µm diameter pixels that can independently deliver K+ ions to precise areas in the cell culture.
• Each pixel is independently controlled, allowing for high spatial resolution in ion delivery, which is important for studying localized effects in cell cultures.
• The device was further characterized using simulations to understand how K+ ions diffuse over time, confirming that the ion pump can deliver K+ ions to targeted locations with high precision.

How Was This Ion Pump Used in Cell Culture Studies? (Application)

• THP-1 macrophages were cultured using the ion pump to investigate how changes in K+ concentration affect cell behavior.
• During the experiment, a membrane voltage-sensitive dye (DiBAC4(3)) was used to monitor cell depolarization (changes in the cell’s electrical charge).
• By modulating K+ concentration, the researchers were able to observe depolarization of the macrophages over time, showing how K+ influences cell membrane potential.

What is Closed-Loop Control? (Advanced Control Mechanism)

• The ion pump system was integrated with a closed-loop control algorithm, which allows the device to adjust K+ delivery in response to real-time feedback from the cell culture.
• A machine-learning algorithm was used to fine-tune the voltage applied to the ion pump to keep the K+ concentration within a desired range, allowing for precise control over cell behavior.
• This closed-loop system can track specific patterns, like a sine wave, and adjust the ion delivery accordingly to match the expected results.

What Are the Potential Applications of These Ion Pumps?

• The ion pump design is not limited to potassium ions; it can also be used to deliver other ions (like protons or calcium) or even small molecules (like neurotransmitters) in biological systems.
• This flexibility allows for multiple ion or molecule types to be delivered simultaneously, offering even more control over biological processes in experiments.

Key Conclusions (Summary)

• This research presents two types of ion pumps that modulate potassium ion concentrations for in vitro cell culture studies with high spatial resolution.
• The ion pumps were successfully tested and shown to affect cell behavior, including the membrane potential of THP-1 macrophages.
• The integration of a closed-loop control system allows precise, real-time control of potassium delivery, which could enable long-term biological control for experiments and applications in bioelectronics.

观察到了什么？ (引言)

• 生物电子设备通过电子信号控制生物系统，弥合了生物学和电子学之间的鸿沟。
• 钾离子 (K+) 在细胞功能中起着至关重要的作用，包括维持细胞膜电位 (Vmem) 和生成动作电位（细胞的电信号）。
• 本研究展示了两种用于调节体外细胞培养中钾离子浓度的生物电子离子泵，允许精确控制细胞在实验室中的行为。
• 研究的重点是开发生物电子系统，以控制细胞培养实验中的钾离子浓度，更好地了解其对细胞的影响，比如 THP-1 巨噬细胞（一种免疫细胞）。

什么是生物电子离子泵？

• 生物电子离子泵是一种利用电子信号产生的电场，通过溶液中转移特定离子（如钾离子）的设备。
• 这些泵用于模拟生物过程，允许研究人员在受控环境中操控离子浓度。
• 离子泵在减少炎症、治疗癫痫、细胞分化和促进伤口愈合等方面具有应用。

钾在细胞中的作用是什么？

• 钾（K+）对维持细胞内外液体和电荷的平衡至关重要。
• 它帮助维持膜电位（Vmem），就像为细胞电功能提供电力的电池。
• 钾离子对神经功能、肌肉收缩和保持健康的心血管系统非常重要。

这些离子泵是如何工作的？ (设备概述)

• 第一个离子泵是基于 PDMS 的设备，直接适配到标准的六孔细胞培养板中。
• 设备使用电压将 K+ 离子从储液槽移动到需要的目标区域，帮助研究人员控制细胞实验中的离子浓度。
• 第二种离子泵是先进的片上设备，具有高空间分辨率，可以将 K+ 离子精确送到细胞培养的特定位置。

如何测试离子泵？ (结果)

• 离子泵在六孔细胞培养板中通过荧光显微镜进行实时测试，监测钾离子的传递。
• 使用如 ION Potassium Green-2 (IPG-2) 这样的荧光染料来测量钾离子浓度的变化，随着 K+ 浓度的增加，荧光强度也增加。
• 通过施加正负电压（1.5 V 和 -1.5 V），使 K+ 离子在储液槽和目标区域之间流动。
• 记录设备产生的电流，计算传递到目标的钾离子数量。
• 研究结果表明，施加更高的电压和更高的 KCl 浓度会导致更多的 K+ 离子传递到目标区域。

空间分辨率是如何工作的？ (先进的泵设计)

• 先进的片上离子泵具有微通道阵列，每个像素可以独立控制，将 K+ 离子精确送到细胞培养的特定区域。
• 每个像素独立控制，允许在离子传递中实现高空间分辨率，对于研究细胞培养中的局部效应非常重要。
• 通过模拟，研究人员进一步验证了 K+ 离子如何随着时间的推移扩散，确认了离子泵可以高精度地将 K+ 离子送到目标位置。

如何在细胞培养中应用这些离子泵？ (应用)

• THP-1 巨噬细胞在离子泵的作用下培养，研究钾离子浓度变化对细胞行为的影响。
• 在实验过程中，使用膜电位敏感染料（DiBAC4(3)）监测细胞去极化（细胞电荷的变化）。
• 通过调节 K+ 浓度，研究人员观察到巨噬细胞膜电位的变化，显示了 K+ 如何影响细胞膜电位。

什么是闭环控制？ (高级控制机制)

• 离子泵系统与闭环控制算法集成，使得设备可以根据细胞培养中的实时反馈精确调节钾离子的传递。
• 通过机器学习算法，精确调整离子泵的电压，以确保 K+ 浓度保持在期望范围内，从而精确控制细胞的行为。
• 该闭环系统可以跟踪特定的波形，例如正弦波，并根据设定轨迹调整离子传递。

这些离子泵的潜在应用是什么？

• 这些离子泵设计不仅限于钾离子，还可以用于传递其他离子（如质子或钙）或甚至小分子（如神经递质）。
• 这种灵活性允许同时传递多种离子或分子，进一步增强了对生物过程的控制能力。

主要结论 (总结)

• 本研究展示了两种离子泵，能够在体外细胞培养中调节钾离子浓度，并具有高空间分辨率。
• 离子泵成功地被测试并显示出改变细胞行为的效果，包括 THP-1 巨噬细胞膜电位的变化。
• 闭环控制系统的集成使得离子泵能够精确控制钾离子的传递，这为长时间的生物学控制提供了巨大潜力。