Binding of the chemokine CXCL12α to its natural extracellular matrix ligand heparan sulfate enables myoblast adhesion and facilitates cell motility

The chemokine CXCL12α is a potent chemoattractant that guides the migration of muscle precursor cells (myoblasts) during myogenesis and muscle regeneration. To study how the molecular presentation of chemokines influences myoblast adhesion and motility, we designed multifunctional biomimetic surfaces as a tuneable signalling platform that enabled the response of myoblasts to selected extracellular cues to be studied in a well-defined environment. Using this platform, we demonstrate that CXCL12α, when presented by its natural extracellular matrix ligand heparan sulfate (HS), enables the adhesion and spreading of myoblasts and facilitates their active migration. In contrast, myoblasts also adhered and spread on CXCL12α that was quasi-irreversibly surface-bound in the absence of HS, but were essentially immotile. Moreover, co-presentation of the cyclic RGD peptide as integrin ligand along with HS-bound CXCL12α led to enhanced spreading and motility, in a way that indicates cooperation between CXCR4 (the CXCL12α receptor) and integrins (the RGD receptors). Our findings reveal the critical role of HS in CXCL12α induced myoblast adhesion and migration. The biomimetic surfaces developed here hold promise for mechanistic studies of cellular responses to different presentations of biomolecules. They may be broadly applicable for dissecting the signalling pathways underlying receptor cross-talks, and thus may guide the development of novel biomaterials that promote highly specific cellular responses

Small angle neutron scattering studies and kinetic analysis of laponite–enzyme hydrogels in view of biosensors construction

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Interfacial and micellar behaviour of pyrrole-containing surfactants

International audienceThe physicochemical properties of new electropolymerisable cationic surfactants having a pyrrolyl group attached and unusual counterions have been studied in aqueous solutions and at the air-water interface. The tetrafluoroborate and tosylate anions behave as quite hydrophobic counterions as compared to the conventional bromide. The pyrrolyl group of moderate polarity has a dual behaviour: it behaves as a hydrophobic substituent when it is attached close to the polar head of the surfactants, but its low polarity manifests when it is attached to the end of the hydrophobic chain. Thus, the presence of the pyrrolyl group at the chain end does not affect the cmc value. The pyrrole ring was found located at the micellar surface in the dilute regime; the resulting folding of the hydrophobic chain induces a strong curvature of the interface; small and spherical micelles are formed. A concentrated regime is reached where the interfacial curvature is reduced: the micelles progressively grow in size and change their shape into elongated ellipsoids. The increasing lateral interactions at the level of the headgroups expel the pyrrolyl groups into the hydrophobic micellar core

Redox strategy for reversible attachment of biomolecules using bifunctional linkers

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Cell adhesion through clustered ligand on fluid supported lipid bilayers

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Nickel (II) tetraphenylporphyrin modified surfaces via electrografting of an aryldiazonium salt

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Electropolymerization of Cationic Amphiphilic Pyrrole Derivatives on Electrodes. Evidence for Environmental Effects on Redox Potentials of Trapped Anions

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Redox-Driven Host-Guest Interactions Allow the Controlled Release of Captured Cells on RGD-Functionalized Surfaces

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Unlimited growth of host–guest multilayer films based on functionalized neutral polymers

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Impact of Conformational Transitions on SPR Signals—Theoretical Treatment and Application in Small Analytes/Aptamer Recognition

International audienceSurface plasmon resonance (SPR) is a powerful technique for label-free and real-time characterization of molecular interactions at interfaces. However, the detection of small molecules still remains a challenge. Here, we report on the direct detection of a low-molecular-weight compound by its receptor presented as a monolayer. Moreover, the signal observed is more than twice the expected mass-weighted response. To establish the origin of the signal enhancement, we present herein a theoretical model that simulates the maximal SPR response by taking into account the aptamer conformational change. We demonstrated that the variation of layer thickness is not the only parameter to be considered. We highlighted that the conformational transition of the aptamer also induces a deviation of the refractive index increment (RII) of the target/aptamer complex from the sum of the RII of individual entities. This nonadditivity of the RII significantly contributes to the magnitude of the signal. We also propose the prediction of the maximal SPR response as a function of the penetration depth, the ratio of the mass-weighted RII of the partners, the sensing layer thickness, and the correction of the complex RII. This model provides new insights into parameters to be considered for the analysis of SPR signals