The effect of a Mn(III)tetrakis(4-benzoic acid)porphyrin (MnTBAP) coating on the chronic recording performance of planar silicon intracortical microelectrode arrays

Reactive Amine Functionalized Microelectrode Arrays Provide Short-Term Benefit but Long-Term Detriment to In Vivo Recording Performance

“…Square silicon tabs (1 cm × 1 cm, Catalog #1575, University Wafers, South Boston, MA, USA) and implantable MEAs were coated with APTES following previously described procedures. , Implantable MEAs used for this investigation were single-shank, 16-channel laminar silicon devices with silicon dioxide encapsulation (SiO 2 ), and a silicon substrate. Functional devices were purchased from NeuroNexus (A1 × 16–3–100–177-CM16LP, iridium electrode sites, NeuroNexus Technologies, Ann Arbor, MI, US).…”

“…Homogenized samples were sent to the Gene Expression and Genotyping Facility at Case Western Reserve University for RNA isolation. ,, The RNeasy Plus Universal Mini Kit (Qiagen 73404) was used to isolate the RNA. Nanodrop and TapeStation systems were used to check the RNA quantity.…”

“…Several groups have recently explored the use of bioactive coatings, with the goal to mitigate neuroinflammation related to decreased chronic recording performance. For example, recent investigations have demonstrated improved chronic recording performance or decreased tissue response with coatings of dexamethasone loaded nitrocellulose, laminin, peptides, neurotrophins loaded polypyrrole, and antioxidants. , However, the silicon dioxide surfaces of MEAs may often require an intermediate functionalization step providing a more reactive surface for attaching bioactive molecules. For example, He et al use polyethylenimine to functionalize the surface of planar silicon MEAs to initiate the self-assembly of laminin to the surface .…”

“…For example, He et al use polyethylenimine to functionalize the surface of planar silicon MEAs to initiate the self-assembly of laminin to the surface . Alternatively, silane chemistries have been used in attaching the L1 neuro-adhesive molecule to silicon substrates used both in vitro and in vivo − and to attach an antioxidant compound to intracortical MEAs. , The organosilane (3-aminopropyl)­triethoxysilane (APTES) is often used for this purpose. ,− APTES molecules form a self-assembled monolayer, which serves as a reactive linker for a range of bioactive molecules. This approach has been used to promote the attachment of antibodies on silicon dioxide-based chips, acetylcholinesterase and choline oxidase onto carbon nanodots, uricase enzyme onto indium tin oxide surfaces bioactive peptides onto polyimide-insulated microwires, extracellular matrix proteins on polydimethylsiloxane surfaces for neuronal culture, glucose oxidase onto carbon nanotubes, and synthetic antioxidants onto microelectrode arrays .…”

“…Alternatively, silane chemistries have been used in attaching the L1 neuro-adhesive molecule to silicon substrates used both in vitro and in vivo − and to attach an antioxidant compound to intracortical MEAs. , The organosilane (3-aminopropyl)­triethoxysilane (APTES) is often used for this purpose. ,− APTES molecules form a self-assembled monolayer, which serves as a reactive linker for a range of bioactive molecules. This approach has been used to promote the attachment of antibodies on silicon dioxide-based chips, acetylcholinesterase and choline oxidase onto carbon nanodots, uricase enzyme onto indium tin oxide surfaces bioactive peptides onto polyimide-insulated microwires, extracellular matrix proteins on polydimethylsiloxane surfaces for neuronal culture, glucose oxidase onto carbon nanotubes, and synthetic antioxidants onto microelectrode arrays . There is evidence that modification with APTES and other compounds with amine functional groups alone can promote cellular attachment and viability in vitro on materials including glass, titanate nanotubes, conducting polymer nanofibrous scaffolds, silicon and silicon dioxide, − and the platinum electrodes of MEAs. , Interestingly, prior work suggests that there may be improved coupling, albeit acutely, of excitable cells to APTES-modified microelectrode sites such that recorded peak-to-peak amplitude reaches the mV range. , Although APTES and other silane coatings are being used as functionalization steps in these studies, their effect alone on neural recordings has not been characterized previously in vivo .…”