Surface-Bound Soft Matter Gradients

Genzer, Jan; Bhat, Rajendra R.

doi:10.1021/la7033164

Cited by 331 publications

(351 citation statements)

References 255 publications

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“…4 Movements of the droplet could be also controlled by the shape, frequency, and amplitude of the vibration. 14 Moreover, liquid droplet could even move uphill on elaborate designed shape-gradient composite surfaces. 15 Today, the combination of roughness gradient designed substrate and surface tension effect has been applied in micro-pumps for various applications.…”

Section: Introductionmentioning

confidence: 99%

Driving Droplet by Scale Effect on Microstructured Hydrophobic Surfaces

Hao

2012

Langmuir

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Abstract:A new type of water droplet transportation on microstructured hydrophobic surface is proposed and investigated experimentally and theoretically -water droplet could be driven by scale effect which is different from the traditional methods. Gradient microstructured hydrophobic surface is fabricated in which the area fraction is kept constant, but the scales of the micro-pillars are monotonic changed. When additional water or horizontal vibration is applied, the original water droplet could move unidirectionally to the direction from the small scale to the large scale to decrease its total surface energy. A new mechanism based on line tension model could be used to explain this phenomenon. It is also found that dynamic contact angle decreases with increasing the scale of the micro-pillars along the moving direction. These new findings will deepen our understanding of the relationship between topology and wetting properties, and could be very helpful to design liquid droplet transportation device in microfluidic systems.

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Section: Introductionmentioning

confidence: 99%

Driving Droplet by Scale Effect on Microstructured Hydrophobic Surfaces

Hao

2012

Langmuir

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“…After decades of research on gradient surfaces (Genzer and Bhat, 2008), some sophisticated methods have been developed. These systems (Baier and Bonhoeffer, 1992;Dertinger et al, 2002;Moore et al, 2006) mostly required sophisticated device fabrication and experimental set-up, large amounts of protein, and relatively long preparation time.…”

Section: Introductionmentioning

confidence: 99%

Axon Initiation and Growth Cone Turning on Bound Protein Gradients

John

Fok²,

Gao³

et al. 2009

Journal of Neuroscience

128

113

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Extracellular gradients of secreted guidance factors are known to guide axon pathfinding and neuronal migration. These factors are likely to bind to cell surfaces or extracellular matrix, but whether and how they may act in bound gradients remains mostly unclear. In this study, we have developed a new technique for rapid production of stable microscopic gradients of substrate-bound proteins by covalent bonding of the proteins with an epoxy-coated glass substrate while they are diffusing in an agarose gel. Using this method, we found that bound gradients of netrin-1 and brain-derived neurotrophic factor (BDNF) can polarize the initiation and turning of axons in cultured hippocampal neurons. Furthermore, bound BDNF gradient caused attractive and repulsive polarizing response on gradients of low-and high-average density of BDNF, respectively. This novel bidirectional response to BDNF depended on the basal level of cAMP in the neuron. Finally, our data showed that the neuron's attractive response to bound BDNF gradient depended on the absolute difference rather than the relative difference in the BDNF density across the neuron, with a minimal effective difference of 1-2 BDNF molecule/m 2 on the substrate surface. Thus, substrate-bound guidance factors are highly effective in polarizing axon initiation and growth, and the diffusive printing technique is useful for studying neuronal responses induced by bound protein gradients.

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“…Many approaches have been employed to produce scaffolds with biochemical gradients to control cell behaviour [1,5]. These methods include internal microfluidic channels [6][7][8], controlled protein release using drug delivery systems [9][10][11][12], gradual immobilization of signalling molecules throughout the scaffold geometry [13][14][15], simple molecular diffusion throughout the scaffold [16,17] or combinations of these methods [18][19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Highly efficient intracellular transduction in three-dimensional gradients for programming cell fate

et al. 2016

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Fundamental behaviour such as cell fate, growth and death are mediated through the control of key genetic transcriptional regulators. These regulators are activated or repressed by the integration of multiple signalling molecules in spatio-temporal gradients. Engineering these gradients is complex but considered key in controlling tissue formation in regenerative medicine approaches. Direct programming of cells using exogenously delivered transcription factors can by-pass growth factor complexity but there is still a requirement to deliver such activity spatio-temporally.We previously developed a technology termed GAG-binding enhanced transduction (GET) to efficiently deliver a variety of cargoes intracellularly using GAG-binding domains to promote cell targeting, and cell penetrating peptides (CPPs) to allow cell entry. Herein we demonstrate that GET can be used in a three dimensional (3D) hydrogel matrix to produce gradients of intracellular transduction of mammalian cells.Using a compartmentalized diffusion model with a source-gel-sink (So-G-Si) assembly, we created gradients of reporter proteins (mRFP1-tagged) and a transcription factor (TF, myogenic master regulator MyoD) and showed that GET can be used to deliver molecules into cells spatio-temporally by monitoring intracellular transduction and gene expression programming as a function of location and time.The ability to spatio-temporally control the intracellular delivery of functional proteins will allow the establishment of gradients of cell programming in hydrogels and approaches to direct cellular behaviour for many regenerative medicine applications.

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Surface-Bound Soft Matter Gradients

Cited by 331 publications

References 255 publications

Driving Droplet by Scale Effect on Microstructured Hydrophobic Surfaces

Driving Droplet by Scale Effect on Microstructured Hydrophobic Surfaces

Axon Initiation and Growth Cone Turning on Bound Protein Gradients

Highly efficient intracellular transduction in three-dimensional gradients for programming cell fate

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