Influence of pH on the build-up of poly-L-lysine/heparin multilayers

Barrantes, Alejandro; Santos, Olga; Sotres, Javier; Arnebrant, Thomas

doi:10.1016/j.jcis.2012.08.008

Cited by 36 publications

(44 citation statements)

References 55 publications

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“…1A). PLL has been shown to bind heparin with high affinity due to the high electrostatic interactions of the two molecules [76]. A toluidne blue binding assay was employed to measure the heparin concentration, which reached 0.763±0.05µg/cm 2 (Fig.…”

Section: Resultsmentioning

confidence: 99%

Capture of endothelial cells under flow using immobilized vascular endothelial growth factor

Smith¹,

Koobatian²,

Shahini³

et al. 2015

Biomaterials

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We demonstrate the ability of immobilized vascular endothelial growth factor (VEGF) to capture endothelial cells (EC) with high specificity under fluid flow. To this end, we engineered a surface consisting of heparin bound to poly-L-lysine to permit immobilization of VEGF through the C-terminal heparin-binding domain. The immobilized growth factor retained its biological activity as shown by proliferation of EC and prolonged activation of KDR signaling. Using a microfluidic device we assessed the ability to capture EC under a range of shear stresses from low (0.5 dyne/cm2) to physiological (15 dyne/cm2). Capture was significant for all shear stresses tested. Immobilized VEGF was highly selective for EC as evidenced by significant capture of human umbilical vein and ovine pulmonary artery EC but no capture of human dermal fibroblasts, human hair follicle derived mesenchymal stem cells, or mouse fibroblasts. Further, VEGF could capture EC from mixtures with non-EC under low and high shear conditions as well as from complex fluids like whole human blood under high shear. Our findings may have far reaching implications, as they suggest that VEGF could be used to promote endothelialization of vascular grafts or neovascularization of implanted tissues by rare but continuously circulating EC.

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Section: Resultsmentioning

confidence: 99%

Capture of endothelial cells under flow using immobilized vascular endothelial growth factor

Smith¹,

Koobatian²,

Shahini³

et al. 2015

Biomaterials

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“…The density of the adsorbed layer was fixed at 1050 kg m −3 , which lies between that of pure water (1000 kg m −3 ) and pure protein (1350 kg m −3 ). This approximation was validated for a related system 37 and was reported to have minimal impact on the final modeled thickness 38,39 .…”

Section: Methodsmentioning

confidence: 96%

Cell Patterning with Mucin Biopolymers

et al. 2013

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The precise spatial control of cell adhesion to surfaces is an endeavor that has enabled discoveries in cell biology and new possibilities in tissue engineering. The generation of cell-repellent surfaces currently requires advanced chemistry techniques and could be simplified. Here we show that mucins, glycoproteins of high structural and chemical complexity, spontaneously adsorb on hydrophobic substrates to form coatings that prevent the surface adhesion of mammalian epithelial cells, fibroblasts, and myoblasts. These mucin coatings can be patterned with micrometer precision using a microfluidic device, and are stable enough to support myoblast differentiation over seven days. Moreover, our data indicate that the cell-repellent effect is dependent on mucin-associated glycans because their removal results in a loss of effective cell-repulsion. Last, we show that a critical surface density of mucins, which is required to achieve cell-repulsion, is efficiently obtained on hydrophobic surfaces, but not on hydrophilic glass surfaces. However, this limitation can be overcome by coating glass with hydrophobic fluorosilane. We conclude that mucin biopolymers are attractive candidates to control cell adhesion on surfaces.

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“…It might be partially explained as follows: heparin, an anticoagulant that commonly used in clinical practice of an artificial liver, is a highly charged polyanion . As α‐APA microcapsules are formed through nonspecific binding of polyanion–polycation interactions between alginate and poly( l ‐lysine), heparin may serve as a competitive combine with poly( l ‐lysine), leading to a weaker interaction between alginate and poly( l ‐lysine) and exhibiting a declined stability of microcapsules. However, it is worth pointing out that based on the results of the stability test and immunoisolation property test, it could be concluded that the function of α‐APA microcapsules that serve as a protective barrier between the encapsulated cells and the host environment was well maintained under the clinically relevant dose of heparin even though their decreased stability.…”

Section: Resultsmentioning

confidence: 99%

Effect of plasma components on the stability and permeability of microcapsule

Chen

Zhang

Shen

et al. 2013

J Biomedical Materials Res

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Immobilization of hepatocytes in microcapsules has been a potentially alternative methodology for bioartificial livers (BALs). Moreover, the stability and permeability are the key parameters of these microcapsules. However, these alginate-based microcapsules are unstable if the surrounding medium disrupts the ionic interactions between alginate and the polycation. As hundreds of components are included in human plasma, the stability and permeability in plasma of microcapsules need to be sufficiently investigated. In the present study, the stability of three kinds of alginate-based microcapsules was evaluated when they were immersed in plasma. Our results showed that stability of alginate-a-poly (L-lysine)-alginate (a-APA) microcapsules was well maintained, better than those of alginate-e-poly (L-lysine)-alginate (e-APA) and alginate-chitosan-alginate (ACA) microcapsules.Also, factors affecting the stability of microcapsules in plasma were analyzed and it showed that heparin was the key factor that affected the stability of a-APA microcapsules, whereas heparin and low molecular electrolytes such as HCO 3 2 and H 2 PO 4 2 =HPO 4 22 were the factors to e-APA and ACA microcapsules. In addition, the permeability evaluation showed no decrease in permeability of microcapsules after incubation in plasma. Our study might provide a foundation for the selection and modification of materials for microcapsule-based BAL devices.

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Influence of pH on the build-up of poly-L-lysine/heparin multilayers

Cited by 36 publications

References 55 publications

Capture of endothelial cells under flow using immobilized vascular endothelial growth factor

Capture of endothelial cells under flow using immobilized vascular endothelial growth factor

Cell Patterning with Mucin Biopolymers

Effect of plasma components on the stability and permeability of microcapsule

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