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. Author manuscript; available in PMC: 2020 Oct 1.
Published in final edited form as: Adv Healthc Mater. 2019 Aug 28;8(19):e1900558. doi: 10.1002/adhm.201900558

Figure 3:

Figure 3:

Examples of MEA property modifications. Schematics demonstrating different types of surface modifications, including both surface chemistry (A) and topography (C), as well as modifications to surface geometry (E) and stiffness (G) are provided. (B1, B2) Glial fibrillary acidic protein (GFAP) stains comparing glial reactivity between an uncoated MEA (B1) with an MEA coated with astrocyte ECM (B2). The MEA coated with ECM showed reduced gliosis compared to uncoated MEA. (B3, B4) Surface images of uncoated MEA (B3) and astrocyte ECM coated MEA (B4). Reprinted from [61], Copyright 2018, with permission from Elsevier. (D) Scanning electron microscopy (SEM) images of an unaltered MEA surface (D1) and MEA surface coated with nanoporous gold (D2). GFAP fluorescence images show reduced astrocytic coverage of nanoporous gold surface (D4), which had a 10% astrocytic coverage, compared to unaltered MEA surface (D3), which had a 23% astrocytic coverage. Reprinted (adapted) with permission from [74]. © 2015 American Chemical Society. (F1, F2) Histological GFAP staining of neural tissue with cylindrically shaped MEA implant, demonstrating limited tissue reaction resulting from the aforementioned applied geometry. (F3) Optical micrograph image of cylindrically shaped MEA implant. (F4, F5) GFAP stains comparing resulting gliosis between two different geometries, including floating (F4) and Michigan (F5) MEAs are also provided. Modified with permission and licensed under Creative Commons Attribution BY-NC-ND 4.0: © Biomed. Eng.-Biomed. Tech. [88]. Modified with permission and licensed under Creative Commons Attribution CC-BY 3.0: © Journal of Neural Engineering [89]. (H1) GFAP overlaid with neuronal nuclei (NeuN) demonstrating efficacy of using temporary MEA stiffening with dissolvable coatings for insertion into the brain. (H2) Electron micrograph image of dextran coating. (H3, H4) GFAP stains comparing an uncoated, stiff MEA (H3) with a stiff MEA coated with a 200 μm thick layer of soft, compliant hydrogel (H4). (H5) Image of soft hydrogel coating on MEA. Modified with permission and licensed under Creative Commons Attribution CC-BY 4.0. © Micromachines [97a]. Modified with permission and licensed under Creative Commons Attribution CC-BY 3.0 [97b]. Modified with permission and licensed under Creative Commons Attribution CC-BY 4.0. © Scientific Reports [102].