离子通道掺杂脂质膜组成的生物分子记忆器的组装与表征
Summary
软、低功耗、生物分子记忆电阻利用生物突触的相似成分、结构和切换机制。本文提出了一种从油中水滴之间形成的绝缘脂质双层层中获得的生物分子记忆器的组装和表征方案。电压活化的阿米西林肽的加入导致膜上的记忆离子电导。
Abstract
能够在合成电路元素中重现突触功能对于寻求模仿具有同等效率和密度的大脑认知能力的神经形态计算系统至关重要。迄今为止, 硅基三端晶体管和双端记忆电阻器在神经形态电路中得到了广泛的应用, 这在很大程度上是由于它们能够进行同地定位的信息处理和存储器。然而, 这些设备无法实现大脑的互连性和复杂性, 因为它们耗电, 无法模拟关键的突触功能, 并受到高噪声和高开关电压的影响。为了克服这些限制, 我们开发并表征了一种生物分子记忆电阻器, 该记忆器模拟了生物突触的组成、结构和开关特性。在这里, 我们描述了生物分子记忆器的组装和表征过程, 其中包括 5 nw 厚的脂质双层在油中的脂质功能化水滴之间形成的, 并掺杂了电压活化的醛氧西林肽。虽然类似的组装协议已被用来研究生物物理特性的液支持脂膜和膜结合离子通道, 本文的重点是关键的修改液滴接口双层法必不可少的实现稳定的电阻器性能。具体而言, 我们描述了脂质体的制备过程和在脂质双层膜中加入类似霉素肽的过程, 以及每个成分的适当浓度及其对记忆电阻器整体响应的影响。我们还详细介绍了生物分子记忆器的表征过程, 包括测量和分析通过循环伏安法获得的记忆电流-电压关系, 以及短期可塑性和学习响应阶跃化电压脉冲列车。
Introduction
人们普遍认识到, 生物突触是大脑高效和巨大平行的原因, 因为它们能够以高度适应性的方式学习和处理信息。这种协调的功能产生于多个高度复杂的分子机制, 这些机制驱动短期和长期突触可塑性1、2、3、4、5。神经形态计算系统的目标是在接近大脑密度、复杂性和能量效率的水平上模拟突触功能, 这是下一代类似大脑的计算机所需要的 6,7,8. 然而, 使用传统的电子电路元件复制突触特征几乎是不可能的, 而是需要设计和制造能够适应传入信号和记忆的新硬件元件信息历史9。这些类型的突触启发硬件被称为 mem-tem-mecemtem-memtemtemt”9 、10、11 (内存元素的缩写), 根据 di ventra 等人的说法, 这些硬件是被动的,双终端设备, 其电阻、电容或电感可以根据外部刺激重新配置, 并且可以记住先前的状态11。为了达到接近大脑能量消耗的水平, 这些元素应该使用类似的材料和机制来实现突触可塑性12。
迄今为止, 双端记忆电阻器13,14,15主要是使用互补金属氧化物半导体 (cmos) 技术制造的, 其特点是开关电压高、噪声高。由于高功耗和低密度, 该技术不能很好地扩展。为了解决这些限制, 最近建造了多个有机和聚合物记忆电阻器。然而, 由于通过导电聚合物基体 16,17 进行耗时的离子扩散, 这些器件的开关动力学明显变慢。因此, 基于 cmos 的记忆装置和有机记忆装置模仿突触激发的功能的机制是高度现象学的, 只包含一些突触功能, 如尖峰定时依赖可塑性 (stdp)1 8日, 同时忽视了其他关键特征, 这些特征也在使大脑成为一台强大而高效的电脑方面发挥着至关重要的作用, 比如突触前、短期可塑性19日。
最近, 我们推出了一类新型的记忆装置12 , 其特点是在仿生脂质膜中加入了电压激活肽, 模拟了生物分子组成、膜结构和离子通道触发开关生物突触的机制20。 在这里, 我们描述了如何组装和电气询问这些双终端设备, 特别侧重于如何评估短期可塑性, 以便在在线学习应用程序12中实现。器件组装是基于液滴界面双层 (dib)21方法, 近年来被广泛用于研究模型膜21和膜结合离子通道22,23的生物物理学. 24, 并作为发展刺激反应材料的基石 25,26。我们详细描述了那些对神经形态应用感兴趣, 但在生物材料或膜生物学方面经验有限的人的膜组装和审讯过程。该协议还包括对特性描述过程的完整描述, 考虑到装置27的动态和可重新配置的电气特性, 该过程与组装过程同样重要。这里描述的程序和代表性的结果是基础, 为一类新的低成本、低功耗、基于脂质界面的软记忆元件和其他生物分子, 用于神经形态计算、自主结构和系统的应用,甚至是自适应脑机接口。
Protocol
Representative Results
Discussion
本文提出了一种基于离子通道掺杂合成生物膜在油中两滴水之间形成的生物分子记忆器的组装和表征方案。设计和研究了软物质双端子器件: 1) 克服了与固态技术相关的限制, 如高噪声、高能耗、高开关电压, 2) 更密切地模仿了组合、结构, 生物突触的切换机制, 3) 探索固体装置不表现出的生物突触可塑性的机制和特征。
液滴界面双层技术21, 代表了目前技术<su…
Declarações
The authors have nothing to disclose.
Acknowledgements
国家科学基金会赠款 nsf eccs-1631472 提供了财政支助。对 g. j. t.、c. d. s.、a. b. 和 c. p. c. 的研究部分是由美国能源部的 UT-Battelle, llc 管理的橡树岭国家实验室实验室指导研究和发展方案赞助的。这项研究的一部分是在纳米酶材料科学中心进行的, 该中心是 doe 科学用户设施办公室。
Materials
| 1,2-diphytanoy-sn-glycero-3-phosphocholine (DPhPC) | Avanti Polar Lipids | 850356P/850356C | Purchased as lyophilized powder (P) or in chloroform (C) |
| Agarose | Sigma-Aldrich | A9539 | |
| Agarose (0.5g Agarose Tablets) | Benchmark | A2501 | You can either use the powder form or the tablets |
| Alamethicin | AG Scientific | A-1286 | |
| Analytical balance | Mettler Toledo | ME204TE/00 | |
| Axopatch 200B Amplifier | Molecular Devices | – | |
| BK Precision 4017B 10 MHz DDs Sweep/Function Generator | Digi-Key | BK4017B-ND | |
| Borosilicate Glass Capillaries | World Precision Instruments | 1B100F-4 | |
| Brain Total Lipid Extracts (Porcine) | Avanti Polar Lipids | 131101 | |
| DigiData 1440A system | Molecular Devices | – | |
| Extruder Set With Holder/Heating Block | Avanti Polar Lipids | 610000 | This includes a mini-extruder, 2 syringes, 100 PC membranes, 100 filter supports, and 1 holder/heating block |
| Freezer (-20 °C) | VWR International | SCUCBI0420AD | |
| Glassware | VWR International | – | |
| Hexadecane, 99% | Sigma-Aldrich | 544-76-3 | |
| Isopropyl Alcohol | VWR International | BDH1133-4LP | |
| Microelectrode Holder | World Precision Instruments | MEH1S | |
| MOPS | Sigma-Aldrich | M1254 | |
| Nitrogen (N2) Gas | Airgas | UN1066 | |
| Parafilm M All-Purpose Laboratory Film | Parafilm | PM999 | |
| Powder Free Soft Nitrile Examination Gloves | VWR International | CA89-38-272 | |
| Precleaned Microscope Sildes | Fisher Scientific | 22-267-013 | |
| Refrigirator (4 °C) | VWR International | SCUCFS-0504G | |
| Silver wire | GoodFellow | 147-346-94 | Different diameters could be used depending on the application |
| Sodium Chloride (KCl) | Sigma-Aldrich | P3911 | |
| Stirring Hot Plate | Thermo Scientific | SP131325 | |
| VWR Light-Duty Tissue Wipers | VWR International | 82003-820 | |
| VWR Scientific 50D Ultrasonic Cleaner | VWR International | 13089 |
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