Neuronano Research Center, Department of Experimental Medicine, Lund University, Lund, Sweden.
Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
Sci Rep. 2023 Sep 26;13(1):16090. doi: 10.1038/s41598-023-43297-2.
Optogenetics is highly useful to stimulate or inhibit defined neuronal populations and is often used together with electrophysiological recordings. Due to poor penetration of light in tissue, there is a need for biocompatible wave guides. Glass wave guides are relatively stiff and known to cause glia reaction that likely influence the activity in the remaining neurons. We developed highly flexible micro wave guides for optogenetics that can be used in combination with long-lasting electrophysiological recordings. We designed and evaluated polydimethylsiloxane (PDMS) mono-fibers, which use the tissue as cladding, with a diameter of 71 ± 10 µm and 126 ± 5 µm. We showed that micro PDMS fibers transmitted 9-33 mW/mm light energy enough to activate channelrhodopsin. This was confirmed in acute extracellular recordings in vivo in which optogenetic stimulation through the PDMS fibers generated action potentials in rat hippocampus with a short onset latency. PDMS fibers had significantly less microglia and astrocytic activation in the zone nearest to the implant as compared to glass. There was no obvious difference in number of adjacent neurons between size matched wave guides. Micro PDMS wave guide demonstrates in vivo functionality and improved biocompatibility as compared to glass. This enables the delivery of light with less tissue damage.
光遗传学在刺激或抑制特定神经元群体方面非常有用，通常与电生理记录一起使用。由于光在组织中的穿透率较差，因此需要生物相容性的波导。玻璃波导相对较硬，已知会引起胶质细胞反应，这可能会影响剩余神经元的活动。我们开发了高度灵活的微波导用于光遗传学，可以与长时间的电生理记录结合使用。我们设计并评估了聚二甲基硅氧烷（PDMS）单纤维，其利用组织作为包层，直径为 71±10µm 和 126±5µm。我们表明，微 PDMS 纤维传输的 9-33mW/mm 光能量足以激活通道视紫红质。这在体内急性细胞外记录中得到了证实，通过 PDMS 纤维进行光遗传学刺激在大鼠海马体中产生动作电位，潜伏期很短。与玻璃相比，PDMS 纤维在最接近植入物的区域的小胶质细胞和星形胶质细胞激活程度显著降低。与尺寸匹配的波导相比，相邻神经元的数量没有明显差异。与玻璃相比，微 PDMS 波导在体内具有功能和更好的生物相容性。这使得光的传输对组织的损伤更小。
