Coupling Spectroscopic Ellipsometry and Quartz Crystal Microbalance to Study Organic Films at the Solid-Liquid Interface

Richter, Ralf P.; Rodenhausen, Keith B.; Eisele, Nico B.; Schubert, M.

doi:10.1007/978-3-642-40128-2_11

Cited by 23 publications

(29 citation statements)

References 36 publications

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“…The native oxide film, alone or together with a deposited SLB, were modelled as a single transparent Cauchy layer. Areal mass densities were determined through de Fejter's equation [20], using refractive index increments, dn/dc, of 0.15 cm …”

Section: Spectroscopic Ellipsometry (Se)mentioning

confidence: 99%

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Well-defined biomimetic surfaces to characterize glycosaminoglycan-mediated interactions on the molecular, supramolecular and cellular levels

et al. 2014

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a b s t r a c tGlycosaminoglycans (GAGs) are ubiquitously present at the cell surface and in extracellular matrix, and crucial for matrix assembly, cellecell and cell-matrix interactions. The supramolecular presentation of GAG chains, along with other matrix components, is likely to be functionally important but remains challenging to control and to characterize, both in vivo and in vitro. We present a method to create welldefined biomimetic surfaces that display GAGs, either alone or together with other cell ligands, in a background that suppresses non-specific binding. Through the design of the immobilization platform e a streptavidin monolayer serves as a molecular breadboard for the attachment of various biotinylated ligands e and a set of surface-sensitive in situ analysis techniques (including quartz crystal microbalance and spectroscopic ellipsometry), the biomimetic surfaces are tailor made with tight control on biomolecular orientation, surface density and lateral mobility. Analysing the interactions between a selected GAG (heparan sulphate, HS) and the HS-binding chemokine CXCL12a (also called SDF-1a), we demonstrate that these surfaces are versatile for biomolecular and cellular interaction studies. T-lymphocytes are found to adhere specifically to surfaces presenting CXCL12a, both when reversibly bound through HS and when irreversibly immobilized on the inert surface, even in the absence of any bona fide cell adhesion ligand. Moreover, surfaces which present both HS-bound CXCL12a and the intercellular adhesion molecule 1 (ICAM-1) synergistically promote cell adhesion. Our surface biofunctionalization strategy should be broadly applicable for functional studies that require a well-defined supramolecular presentation of GAGs along with other matrix or cell-surface components.

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Section: Spectroscopic Ellipsometry (Se)mentioning

confidence: 99%

“…In particular, QCM-D provides time-resolved information about the assembly process, including overall film morphology and mechanics [19], while SE enables time-resolved and label-free quantification of biomolecular surface densities and binding stoichiometries [20].…”

Section: Introductionmentioning

confidence: 99%

Well-defined biomimetic surfaces to characterize glycosaminoglycan-mediated interactions on the molecular, supramolecular and cellular levels

et al. 2014

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“…Areal mass densities were determined through de Fejter's equation, using refractive index increments, dn/dc, of 0.132 cm 3 /g for b-HS [50][51][52], 0.18 cm 3 /g for all proteins [53,54], 0.15 cm 3 /g for b-cRGD (estimated from the dn/dc of the individual amino acids and the PEG chain using an established method [54][55][56]), and 0.134 cm 3 /g for b-PEG [57]. All measurements were repeated twice and the data represent mean ± standard errors.…”

Section: Spectroscopic Ellipsometry (Se)mentioning

confidence: 99%

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

et al. 2017

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The chemokine CXCL12 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 CXCL12 , 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 CXCL12 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 CXCL12 led to enhanced spreading and motility, in a way that indicates cooperation between CXCR4 (the CXCL12 receptor) and integrins (the RGD receptors). Our findings reveal the critical role of HS in CXCL12 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. KeywordsGlycosaminoglycan; chemokine; cell adhesion and migration; biomimetics; bioactive surfaces; extracellular matrix 3 IntroductionMuscle development and repair are highly organized processes orchestrated by muscle progenitor cells and crucial for body function [1]: skeletal muscle stem cells (satellite cells) that are typically quiescent undergo a series of modifications including activation, proliferation and differentiation into myoblasts in response to muscle injury, and in vitro studies have shown that the migration of myoblasts is crucial for myogenesis and muscle regeneration [2][3][4]. Cell adhesion and migration are early events necessary to achieve cell-cell contacts, which are essential for the alignment of myoblasts, their subsequent fusion and formation of myotubes [2,[4][5][6]. Migration is a complex process that is guided by chemokines, small soluble signalling proteins that exhibit chemoattractant properties [7]. Chemokines are secreted in response to injury but they are also required for the migration of muscle precursor cells during embryogenesis [6]. In particular, the chemokine CXCL12 , previously called stromal cell-derived factor-1 , SDF-1 , and its major receptor CXCR4 have been shown to be important for the migration of myoblasts during myogenesis and muscle regeneration, both in vivo [6,[8][9][10] and in vitro [11][12][13].Once secreted, chemokines are usually sequestered and presented to the cells via the extracellular matrix (ECM), notably via glycosaminoglycans (GAGs) such as heparan sulf...

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“…25 Combined SE/QCM-D measurements were performed with a custom-built open cuvette (~2 mL), as described in detail elsewhere. 26,27 A magnetic stirrer was used to homogenize the cuvette content for a few seconds during sample injection and also during rinsing steps, whereas adsorption proceeded in still solution to guarantee a homogeneously accessible surface and thus enable quantitative correlation of SE and QCM-D responses which were measured on overlapping but non-identical surface areas. 26 Peptide conjugate surface densities were quantified through fitting of the SE data to an optical model using the software CompleteEASE (Woollam) as described in detail elsewhere.…”

Section: Spectroscopic Ellipsometry (Se)mentioning

confidence: 99%

“…The opaque metal film and the β-CD SAM on gold-coated silicon wafers were treated as a single isotropic layer and fitted as a B-spline substrate; the peptide conjugate film was treated as separate, transparent Cauchy layer. Areal mass densities were determined through de Feijter's equation, 27 using a refractive index increment dn/dc = 0.18 cm 3 /g.…”

Section: Spectroscopic Ellipsometry (Se)mentioning

confidence: 99%

Development of a selective cell capture and release assay: impact of clustered RGD ligands

et al. 2017

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There is a growing interest in isolating tumor cells from biological samples. Considering that circulating tumor cells can be rare in blood, it appears challenging to capture these cells onto a surface with high selectivity and sensitivity. In the present paper we describe the design of functionalized surfaces aiming to selectively capture tumor cells by using the RGD peptide ligand either with a tetrameric or a monomeric presentation. β-cyclodextrin-coated self-assembled monolayers were used as platforms for the binding of RGD ligands endowed with a redox ferrocene cluster as the dissociation of the inclusion complex on the surface is accounted for the release of the captured cells upon electrochemical oxidation of ferrocene. For this purpose, we determined suitable RGD densities for both monovalent and tetravalent ligand presentations. The present results indicate that the clustered RGD architecture efficiently improves the selective cell capture at a very low RGD-surface density (∼ 10 RGD/μm 2 ) in comparison with the monovalent presentation (∼ 1000 RGD/ μm 2 ). IntroductionMultivalent interactions are ubiquitously observed in biological systems for a wide range of functions including integrinmediated cell adhesion to extracellular matrix (ECM). 1 Among the integrin receptors, the α V β 3 integrin subclass has received special attention as it is involved in tumour progression such as aggressive metastatic cancer.2 Felding-Habermann et al. have shown that this receptor contributes to circulating tumour cell (CTC) arrest. 3 As cells expressing α V β 3 integrin interact with the ECM through the recognition of the ubiquitous triad sequence RGD (Arg-Gly-Asp), a series of peptides containing the RGD sequence were developed for diagnosis and tumour therapy. 4 The cyclopentapeptide derivatives were found to specifically bind the α V β 3 integrin. 5 Additionally, the multimeric presentation of RGD motifs appears to be a prerequisite for efficient integrin targeting. 6 Our group and others have shown that multimeric compounds exhibit attractive biological properties. 7 Recently, we have reported the benefit of tetrameric RGD derivatives for the near-infrared optical guided surgery of solid tumours 8 and for tumour-targeted drug delivery. Although multimeric RGD compounds show better affinity than their corresponding monomers, 7 few reports have tested how important clustered architectures are for cell binding to RGD-functionalized surfaces. Pioneering studies have demonstrated that nanoscale patterning of RGD ligand presentation significantly influences cell adhesion and spreading. 10 Those surfaces were prepared from highmolecular weight RGD-containing polymers or nanoparticles. Journal NameScheme 1 Synthesis of compounds 1 and 3. Reaction conditions: i) TFA/H2O (7:3), rt, 20 min then TFA/H2O (95:5), rt, 120 min, 44%; ii) NaIO4, H2O, rt, 20 min, 46%; iii) TFA/H2O/CH3CN (7:2:1), rt, 20 min, 42%; iv) CuSO4, THPTA, sodium ascorbate, phosphate buffer pH 7.4/DMF (6/4), 45°C, 150 min, 1: 63%, 3 :71 %. SPPS: solid-ph...

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Coupling Spectroscopic Ellipsometry and Quartz Crystal Microbalance to Study Organic Films at the Solid-Liquid Interface

Cited by 23 publications

References 36 publications

Well-defined biomimetic surfaces to characterize glycosaminoglycan-mediated interactions on the molecular, supramolecular and cellular levels

Well-defined biomimetic surfaces to characterize glycosaminoglycan-mediated interactions on the molecular, supramolecular and cellular levels

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

Development of a selective cell capture and release assay: impact of clustered RGD ligands

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