Adhesion and patterning of cortical neurons on polyethylenimine and fluorocarbon-coated surfaces

Adhesion and patterning of cortical neurons was investigated on isolated islands of neuron-adhesive polyethylenimine (PEI) surrounded by a neuron-repellent fluorocarbon (FC) layer. In addition, the development of fasciculated neurites between the PEI-coated areas was studied over a time period of 15 days. The patterns consisted of PEI-coated wells (diameter 150 /spl mu/m, depth 0.5 /spl mu/m) which were etched in a coating of fluorocarbon (FC) on top of polyimide (PI) coated glass. The separation distance between the PEI-coated wells were varied between 10 and 90 /spl mu/m. This paper shows that chemical patterns of PEI and FC result in highly compliant patterns of adhering cortical neurons after 1 day in vitro. Interconnecting neurite fascicles between PEI-coated wells were especially present on patterns with a separation distance of 10 /spl mu/m after 8 days in vitro. A significant lower number of interconnecting neurite fascicles was observed on 20 /spl mu/m separated patterns. Effective isolation of neurons into PEI-coated wells was achieved on patterns with a separation distance of 80 /spl mu/m as no interconnecting neurite fascicles were observed

Adhesion and patterning of cortical neurons on polyethylenimine and fluorcarboncoated surfaces

In this study adhesion and patterning of cortical neurons on modified glass surfaces was investigated. Patterns of cortical neurons were prepared with a combination of polyethylenimine (PEI) and plasma-deposited fluorocarbon (FC). In addition neurite\ud development and fasciculation of interconnecting neurites between PEI-coated areas was studied. The patterns consisted of PEI-coated circular holes (diameter 150 pm) which were initially etched in a Fluorocarbon (FC) layer. The separation distance between the PEI-coated circular holes was varied from 10 up to 90 pm. This paper shows that the chemical patterns, prepared with a combination of polyethylenimine (PEI) and plasma deposited Fluorocarbon\ud (FC), results in highly compliant patterns of adhering cortical neurons. Furthermore it was shown that interconnecting neurite bundles between neurons on the PEI-coated circular holes were especially present on the pattern with a minimal separation distance (10 pm) between the PEI-coated circular holes. In contrast\ud interconnecting neurite bundles were hardly observed on patterns with a maximal separation distance (90 pm) between the PEI-coated\ud circular holes

Adhesion and neurite development of cortical neurons on micropatterns of polyethylenimine and fluorcarbon

This study aims on the preparation of isolated islands of cortical neurons on modified glass surfaces. Isolated islands of cortical neurons were obtained with a combination of neuron-adhesive polyethylenimine (PEI) and neuron-repellent plasma-deposited fluorocarbon (FC). Neurite development and fasciculation of interconnecting neurites between PEI-coated areas was studied. The patterns consisted of PEI-coated wells (diameter 150 ¿m) which were initially etched in a Fluorocarbon (FC) layer. The separation distance between the PEI-coated wells was varied from 10 up to 90 ¿m. This paper shows that the chemical patterns, prepared with a combination of polyethylenimine (PEI) and plasma deposited Fluorocarbon (FC), results in highly compliant patterns of adhering cortical neurons. Furthermore, it was shown that the occurrence of connecting neurite fascicles between neurons on PEI-coated wells is inversely proportional to the separation distance between the wells. Interconnecting fascicles were especially present on the pattern with a minimal separation distance (10 ¿m) between the PEI-coated wells. In contrast, interconnecting neurite fascicles were not observed on patterns with a minimal separation distance of 80 ¿m between the well

Potential environmental impact of tidal energy extraction in the Pentland Firth at large spatial scales : results of a biogeochemical model

A model study was carried out of the potential large-scale (> 100 km) effects of marine renewable tidal energy generation in the Pentland Firth, using the 3-D hydrodynamics–biogeochemistry model GETM-ERSEM-BFM. A realistic 800 MW scenario and a high-impact scenario with massive expansion of tidal energy extraction to 8 GW scenario were considered. The realistic 800 MW scenario suggested minor effects on the tides, and undetectable effects on the biogeochemistry. The massive-expansion 8 GW scenario suggested effects would be observed over hundreds of kilometres away with changes of up to 10 % in tidal and ecosystem variables, in particular in a broad area in the vicinity of the Wash. There, waters became less turbid, and primary production increased with associated increases in faunal ecosystem variables. Moreover, a one-off increase in carbon storage in the sea bed was detected. Although these first results suggest positive environmental effects, further investigation is recommended of (i) the residual circulation in the vicinity of the Pentland Firth and effects on larval dispersal using a higher-resolution model and (ii) ecosystem effects with (future) state-of-the-art models if energy extraction substantially beyond 1 GW is planned

Adhesion and growth of electrically-active cortical neurons on polyethyleimine patterns microprinted on PEO-PPO-PEO triblockcopolymer-coated hydrophobic surfaces

This paper describes the adhesion and growth of dissociated cortical neurons on chemically patterned surfaces over a time period of 30 days. The presence of neurons was demonstrated by measurement of spontaneous bioelectrical activity on a micropatterned multielectrode array. Chemical patterns were prepared with a combination of neurophobic layers of polyethylenoxide-polypropylenoxide-polyethylenoxide (PEO-PPO-PEO) triblockcopolymers adsorbed onto hydrophobic surfaces and neurophilic microprinted tracks of polyethylenimine (PEI). Results showed that commercially available PEO-PPO-PEO triblockcopolymers F108 and F127 (Synperonics, ICI) significantly reduced the adhesion of neuronal tissue when adsorbed on hydrophobic Polyimide (PI) and Fluorocarbon (FC) surfaces over a time period of eight days. In general, both F108- and F127-coated PI displayed equal or better neurophobic background properties after 30 days. Viability of neuronal tissue after 30 days on PEI microprinted F108- and F127-coated PI was comparable with relatively high viability factors between 0.9 and 1 (scale from 0 to 1). Summarizing, the strategy to combine the neurophobic adsorbed triblock-copolymers F108 and F127 onto hydrophobic surfaces with neurophilic microprinted PEI resulted in relatively long-term neuronal pattern preservation with high numbers of viable neurons present after 30 days

Neural networks on chemically patterned "cultured probe" electrode arrays: network growth and activity patterns

A 'cultured probe' is a hybrid type of neural information transducer or prosthesis, for stimulation and/or recording of neural activity in the brain or the spinal cord (ventral motor region or dorsal sensory region). It consists of a micro electrode array (MEA) on a planar substrate, each electrode being covered and surrounded by a locally confined network of cultured neurons, obtained by chemical patterning of the substrate. The purpose of the cultured cells is that they act as intermediates for collateral sprouts from the in vivo system, thus allowing for an effective and selective neuron electrode interface. As the local neural network will become spontaneously active and has the capability of information processing, one may envisage future applications of these intermediary networks as 'front-end' signal processors. Two aspects of the development of this kind of cultured probe device are described. First, it is shown how substrates can be chemically modified to confine developing networks, cultured from dissociated rat cortex cells, to the surrounding of an electrode site. Secondly, the paper presents results on neuronal activity in such confined, circular networks and synchronized activity between two such interconnected networks

Neuroelectronic interfacing with cultured multielectrode arrays toward a cultured probe

Efficient and selective electrical stimulation and recording of neural activity in peripheral, spinal, or central pathways requires multielectrode arrays at micrometer scale. ¿Cultured probe¿ devices are being developed, i.e., cell-cultured planar multielectrode arrays (MEAs). They may enhance efficiency and selectivity because neural cells have been grown over and around each electrode site as electrode-specific local networks. If, after implantation, collateral sprouts branch from a motor fiber (ventral horn area) and if they can be guided and contacted to each ¿host¿ network, a very selective and efficient interface will result. Four basic aspects of the design and development of a cultured probe, coated with rat cortical or dorsal root ganglion neurons, are described. First, the importance of optimization of the cell-electrode contact is presented. It turns out that impedance spectroscopy, and detailed modeling of the electrode-cell interface, is a very helpful technique, which shows whether a cell is covering an electrode and how strong the sealing is. Second, the dielectrophoretic trapping method directs cells efficiently to desired spots on the substrate, and cells remain viable after the treatment. The number of cells trapped is dependent on the electric field parameters and the occurrence of a secondary force, a fluid flow (as a result of field-induced heating). It was found that the viability of trapped cortical cells was not influenced by the electric field. Third, cells must adhere to the surface of the substrate and form networks, which are locally confined, to one electrode site. For that, chemical modification of the substrate and electrode areas with various coatings, such as polyethyleneimine (PEI) and fluorocarbon monolayers promotes or inhibits adhesion of cells. Finally, it is shown how PEI patterning, by a stamping technique, successfully guides outgrowth of collaterals from a neonatal rat lumbar spinal cord explant, after six days in cultur