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An Electrocorticography Grid with Conductive Nanoparticles in a Polymer Thick Film on an Organic Substrate Improves CT and MR Imaging.

ABSTRACT: Purpose To develop an electrocorticography (ECoG) grid by using deposition of conductive nanoparticles in a polymer thick film on an organic substrate (PTFOS) that induces minimal, if any, artifacts on computed tomographic (CT) and magnetic resonance (MR) images and is safe in terms of tissue reactivity and MR heating. Materials and Methods All procedures were approved by the Animal Care and Use Committee and complied with the Public Health Services Guide for the Care and Use of Animals. Electrical functioning of PTFOS for cortical recording and stimulation was tested in two mice. PTFOS disks were implanted in two mice; after 30 days, the tissues surrounding the implants were harvested, and tissue injury was studied by using immunostaining. Five neurosurgeons rated mechanical properties of PTFOS compared with conventional grids by using a three-level Likert scale. Temperature increases during 30 minutes of 3-T MR imaging were measured in a head phantom with no grid, a conventional grid, and a PTFOS grid. Two neuroradiologists rated artifacts on CT and MR images of a cadaveric head specimen with no grid, a conventional grid, and a PTFOS grid by using a four-level Likert scale, and the mean ratings were compared between grids. Results Oscillatory local field potentials were captured with cortical recordings. Cortical stimulations in motor cortex elicited muscle contractions. PTFOS implants caused no adverse tissue reaction. Mechanical properties were rated superior to conventional grids (χ(2) test, P < .05). The temperature increase during MR imaging for the three cases of no grid, PTFOS grid, and conventional grid was 3.84°C, 4.05°C, and 10.13°C, respectively. PTFOS induced no appreciable artifacts on CT and MR images, and PTFOS image quality was rated significantly higher than that with conventional grids (two-tailed t test, P < .05). Conclusion PTFOS grids may be an attractive alternative to conventional ECoG grids with regard to mechanical properties, 3-T MR heating profile, and CT and MR imaging artifacts. (©) RSNA, 2016 Online supplemental material is available for this article.

SUBMITTER: Ahmadi E

PROVIDER: S-EPMC4949083 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Despite efforts to mature human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) for disease modeling and high throughput screening, cells remain immature and may not reflect adult biology. Recent advancements utilize electro-mechanical and paracrine stimulation to functionally mature cardiomyocytes, but the resulting engineered constructs continue to lack a microenvironment conducive to electrical signal propagation and maturity. Conductive polymers are attractive candidates to facilitate electrical communication between gaps in sparse hPSC-CM clusters or between hPSC-CMs to repair conduction defects. To create a conductive polymer platform for improved electrical signal propagation between hPSC-CMs and achieve electrical maturity, we electrospun poly(3,4-ethylendioxythiophene):polystyrene sulfonate (PEDOT:PSS) blended with 8% (w/v) poly(vinyl alcohol) (PVA). Matrix fiber structure remained stable over 4 weeks in buffer, stiffness remains near cardiac stiffness in vivo, and electrical conductivity scaled with PEDOT:PSS concentration. When fibroblasts were added to fibers, cells had higher initial attachment to PEDOT:PSS compared to PVA-only scaffolds, and after 5 days, over 90% of fibroblasts remained viable on PEDOT:PSS scaffolds compared to PVA-only scaffolds. Electrically excitable hPSC-CMs cultured on conductive substrates exhibited an upregulation of cardiac and muscle-related genes as opposed to non-conductive substrates. These cells further displayed increased desmoplakin (DP) localization on conductive scaffolds, indicating an improvement in the mechanical stability of our hPSC-CMs. Sarcomere organization also scaled with increasing PEDOT:PSS concentration, even in sub-monolayer cell densities, suggesting that improved organization of the contractile machinery in these cells was due to the electrical condition of the matrix. Calcium handling indicated higher calcium flux with a shorter time to peak, further suggesting improved electrical maturity, even when sub-confluent. Taken together, these data suggest that PEDOT:PSS/PVA scaffolds are stable, of a stiffness relevant to cardiomyocytes, and supportive of electrical coupling even in the absence of a monolayer, which may improve cardiac disease modeling and drug development.

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An Electrocorticography Grid with Conductive Nanoparticles in a Polymer Thick Film on an Organic Substrate Improves CT and MR Imaging.

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