Islet-encapsulation in ultra-thin layer-by-layer membranes of poly(vinyl alcohol) anchored to poly(ethylene glycol)–lipids in the cell membrane

Teramura, Yuji; Kaneda, Yoshihiro; Iwata, Hiroo

doi:10.1016/j.biomaterials.2007.07.050

Cited by 211 publications

(174 citation statements)

References 31 publications

Supporting

Mentioning

171

Contrasting

Unclassified

Order By: Relevance

“…Alternatively, pre-treating the glial cell membrane with an anti-fouling agent such as polyethylene glycol or polyvinyl alcohol could also have positive effects in reducing the extent of neuron-glia adhesion. 22 Importantly, the method proposed here is fully compatible with other approaches for signal amplification, e.g., using nanostructured electrodes. 1,4,9-13 These approaches have already been successful in recording large spike signals.…”

mentioning

confidence: 90%

An electrically resistive sheet of glial cells for amplifying signals of neuronal extracellular recordings

Matsumura

Yamamoto

Niwano

et al. 2016

Applied Physics Letters

View full text Add to dashboard Cite

Electrical signals of neuronal cells can be recorded non-invasively and with a high degree of temporal resolution using multielectrode arrays (MEAs). However, signals that are recorded with these devices are small, usually 0.01%-0.1% of intracellular recordings. Here, we show that the amplitude of neuronal signals recorded with MEA devices can be amplified by covering neuronal networks with an electrically resistive sheet. The resistive sheet used in this study is a monolayer of glial cells, supportive cells in the brain. The glial cells were grown on a collagen-gel film that is permeable to oxygen and other nutrients. The impedance of the glial sheet was measured by electrochemical impedance spectroscopy, and equivalent circuit simulations were performed to theoretically investigate the effect of covering the neurons with such a resistive sheet. Finally, the effect of the resistive glial sheet was confirmed experimentally, showing a 6-fold increase in neuronal signals. This technique feasibly amplifies signals of MEA recordings. V C 2016 AIP Publishing LLC. Microelectrode array (MEA) technology is widely used to record trains of action potentials from cultured neurons, cardiomyocytes, or brain slice preparations. [1][2][3][4] The major advantage of this method lies in its high temporal resolution (>10 kHz) and non-invasiveness. MEA recordings have been used both in fundamental studies, e.g., to analyse activity patterns of cultured neuronal networks, 5,6 and in pharmacological research, for screening lead compounds in vitro. 7,8 However, small signals that can be detected through extracellularly positioned microelectrodes inhibit MEAs from being used in further applications such as studies of subthreshold activity. The amplitude of extracellularly recorded signals is usually in the order of ten to a hundred microvolts, which is 3-4 orders of magnitude lower than the intracellular change of membrane potential in an action potential ($100 mV).Various attempts have been made to overcome this issue. One approach involves increasing the seal resistance between the cell and the electrode. This can be achieved by using nanostructured electrodes instead of planar electrodes that become engulfed by overlying cells. 1,9 A second approach is to decrease the electrode impedance. To record activity from single cells, the use of a smaller electrode is preferable, but this comes at the cost of increased electrode impedance, which decreases the signal. Wolfrum et al. overcame this dilemma by creating micropores that interface the cells to larger electrodes. 10,11 A third approach involves decreasing the membrane impedance at the cell-electrode junction. In practice, this involves transiently rapturing the cell membrane by applying a zap voltage to a nanostructured electrode, thus allowing the electrodes to enter the cell and perform pseudo-intracellular recording until the raptured membrane reorganizes. 1,12,13 In this letter, we propose an alternative approach to increase the neuron-electrode seal for amplifying signals in ex...

show abstract

mentioning

confidence: 90%

An electrically resistive sheet of glial cells for amplifying signals of neuronal extracellular recordings

Matsumura

Yamamoto

Niwano

et al. 2016

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…Although alginate remains the most popular hydrogel of choice, agarose [115,116], chitosan [117], methacrylic acid [118], methyl methacrylate [119], polyamide [120,121], PVA [122], PEG [123,124], 2-hydroxyethyl methacrylate (HEMA) [125,126], AN69 (a copolymer of acrylonitrile and sodium-methallyl sulfonate) [127], and collagens type I and IV [128] are all being evaluated for use in islet and stem cell encapsulation. Stimuli-responsive synthetic hydrogels are commonly employed in cell encapsulation and tissue engineering.…”

Section: Synthetic Scaffoldsmentioning

confidence: 99%

Encapsulation technologies in beta cell replacement therapies for Type 1 diabetes

Krishnan¹,

Imagawa²,

Foster³

et al. 2016

Nanomaterials and Regenerative Medicine

View full text Add to dashboard Cite

“…10 Conformal coating has been reported using several two-phase flow techniques, namely, selective withdrawal, 13,14 centrifugation, 15 and bulk emulsification. 16 In addition to these hydrodynamics-based methods, other conformal coating techniques that involve surface chemistry include interfacial polymerization, 17 surface binding with polymer-lipid, 18,19 and layer-bylayer poly(L-lysine)(PLL)-PEG copolymer assembly. 20 Magnetic conformal coating by Khademhosseini et al 3 uses a magnetic force to pull cell aggregates that have a magnetic core through polymer layers in a syringe tube.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic conformal coating of non-spherical magnetic particles

et al. 2014

View full text Add to dashboard Cite

We present the conformal coating of non-spherical magnetic particles in a colaminar flow microfluidic system. Whereas in the previous reports spherical particles had been coated with thin films that formed spheres around the particles; in this article, we show the coating of non-spherical particles with coating layers that are approximately uniform in thickness. The novelty of our work is that while liquid-liquid interfacial tension tends to minimize the surface area of interfacesfor example, to form spherical droplets that encapsulate spherical particles-in our experiments, the thin film that coats non-spherical particles has a non-minimal interfacial area. We first make bullet-shaped magnetic microparticles using a stopflow lithography method that was previously demonstrated. We then suspend the bullet-shaped microparticles in an aqueous solution and flow the particle suspension with a co-flow of a non-aqueous mixture. A magnetic field gradient from a permanent magnet pulls the microparticles in the transverse direction to the fluid flow, until the particles reach the interface between the immiscible fluids. We observe that upon crossing the oil-water interface, the microparticles become coated by a thin film of the aqueous fluid. When we increase the two-fluid interfacial tension by reducing surfactant concentration, we observe that the particles become trapped at the interface, and we use this observation to extract an approximate magnetic susceptibility of the manufactured non-spherical microparticles. Finally, using fluorescence imaging, we confirm the uniformity of the thin film coating along the entire curved surface of the bullet-shaped particles. To the best of our knowledge, this is the first demonstration of conformal coating of non-spherical particles using microfluidics. V C 2014 AIP Publishing LLC. [http://dx

show abstract

Islet-encapsulation in ultra-thin layer-by-layer membranes of poly(vinyl alcohol) anchored to poly(ethylene glycol)–lipids in the cell membrane

Cited by 211 publications

References 31 publications

An electrically resistive sheet of glial cells for amplifying signals of neuronal extracellular recordings

An electrically resistive sheet of glial cells for amplifying signals of neuronal extracellular recordings

Encapsulation technologies in beta cell replacement therapies for Type 1 diabetes

Microfluidic conformal coating of non-spherical magnetic particles

Contact Info

Product

Resources

About