Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience, Soochow University; Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou 215123, China.
School of Nano Technology and Nano Bionics, University of Science and Technology of China, Hefei 230026, China; i-Lab., Key Laboratory of Multifunctional Nanomaterials and Smart Systems, Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123, China; Lihuili Hospital Affiliated to Ningbo University, Ningbo 315211, China.
Acta Biomater. 2022 Oct 15;152:86-99. doi: 10.1016/j.actbio.2022.08.053. Epub 2022 Aug 28.
Hydrogels are widely used in nerve tissue repair and show good histocompatibility. There remain, however, challenges with hydrogels for applications related to neural signal recording, which requires a tissue-like biomechanical property, high optical transmission, and low impedance. Here, we describe a transparent hydrogel that is highly biocompatible and has a low Young's modulus (0.15 MPa). Additionally, it functions well as an implantable electrode, as it conformably adheres to brain tissue, results in minimal inflammation and has a low impedance of 150 Ω at 1 kHz. Its high transmittance, corresponding to 93.35% at a wavelength of 300 nm to 1100 nm, supports its application in two-photon imaging. Consistent with these properties, this flexible multimodal transparent electrophysiological hydrogel (MTEHy) electrode was able to record neuronal Ca activity using miniature two-photon microscopy. It also used to monitor electrocorticogram (ECoG) activity in real time in freely moving mice. Moreover, its compatibility with magnetic resonance imaging (MRI), indicates that MTEHy is a new tool for studying activity in the cerebral cortex. STATEMENT OF SIGNIFICANCE: Future brain science research requires better-performing implantable electrodes to detect neuronal signaling in the brain. In this study, we developed a new hydrogel material, MTEHy-3, that shows high biocompatibility, high optical transmittance (93.35%) and a low Young's modulus (0.15 MPa). Using as high-biocompatible metal-free hydrogel electrode, MTEHy-3 can be implanted for a long time to study the cerebral cortex, and synchronously record the Ca signaling activity of individual neurons and monitor electrocorticogram activity through ionic conduction in freely moving mice. At the same time, non-metallic MTEHy-3 is also suitable for magnetic resonance imaging. Thus MTEHy-3 provides one in situ multimodal tool to detect neuronal signaling with both high spatial resolution and high temporal resolution in the brain.
水凝胶在神经组织修复中得到了广泛的应用，具有良好的组织相容性。然而，在用于神经信号记录的水凝胶方面仍然存在挑战，这需要组织样生物力学特性、高透光率和低阻抗。在这里，我们描述了一种具有高生物相容性和低杨氏模量（0.15 MPa）的透明水凝胶。此外，它作为一种可植入电极效果很好，因为它能与脑组织紧密贴合，导致最小的炎症和低阻抗 150 Ω 在 1 kHz。它的高透光率，在波长 300nm 到 1100nm 时对应 93.35%，支持它在双光子成像中的应用。与这些特性一致，这种灵活的多模态透明电生理水凝胶（MTEHy）电极能够使用微型双光子显微镜记录神经元 Ca 活动。它也用于实时监测自由活动小鼠的脑电图（ECoG）活动。此外，它与磁共振成像（MRI）的兼容性表明，MTEHy 是研究大脑皮层活动的一种新工具。
未来的脑科学研究需要性能更好的植入式电极来检测大脑中的神经元信号。在这项研究中，我们开发了一种新的水凝胶材料 MTEHy-3，它具有高生物相容性、高透光率（93.35%）和低杨氏模量（0.15 MPa）。使用高生物相容性的无金属水凝胶电极，MTEHy-3 可以长期植入以研究大脑皮层，并通过自由活动小鼠中的离子传导同步记录单个神经元的 Ca 信号活动和监测脑电图活动。同时，非金属 MTEHy-3 也适用于磁共振成像。因此，MTEHy-3 提供了一种原位多模态工具，可在大脑中以高空间分辨率和高时间分辨率检测神经元信号。
