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See detailPredicting Ligand-Free Cell Attachment on Next-Generation Cellulose–Chitosan Hydrogels
Johns, Marcus A.; Bae, Yongho; Guimarães, Francisco E. G. et al

in ACS Omega (2018), 3(1), 937--945

There is a growing appreciation that engineered biointerfaces can regulate cell behaviors, or functions. Most systems aim to mimic the cell-friendly extracellular matrix environment and incorporate ... [more ▼]

There is a growing appreciation that engineered biointerfaces can regulate cell behaviors, or functions. Most systems aim to mimic the cell-friendly extracellular matrix environment and incorporate protein ligands; however, the understanding of how a ligand-free system can achieve this is limited. Cell scaffold materials comprised of interfused chitosan–cellulose hydrogels promote cell attachment in ligand-free systems, and we demonstrate the role of cellulose molecular weight, MW, and chitosan content and MW in controlling material properties and thus regulating cell attachment. Semi-interpenetrating network (SIPN) gels, generated from cellulose/ionic liquid/cosolvent solutions, using chitosan solutions as phase inversion solvents, were stable and obviated the need for chemical coupling. Interface properties, including surface zeta-potential, dielectric constant, surface roughness, and shear modulus, were modified by varying the chitosan degree of polymerization and solution concentration, as well as the source of cellulose, creating a family of cellulose–chitosan SIPN materials. These features, in turn, affect cell attachment onto the hydrogels and the utility of this ligand-free approach is extended by forecasting cell attachment using regression modeling to isolate the effects of individual parameters in an initially complex system. We demonstrate that increasing the charge density, and/or shear modulus, of the hydrogel results in increased cell attachment. [less ▲]

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See detailModulating cell response on cellulose surfaces; tunable attachment and scaffold mechanics
Courtenay, James C.; Deneke, Christoph; Martin Lanzoni, Evandro UL et al

in Cellulose (2017)

Combining surface chemical modification of cellulose to introduce positively charged trimethylammonium groups by reaction with glycidyltrimethylammonium chloride (GTMAC) allowed for direct attachment of ... [more ▼]

Combining surface chemical modification of cellulose to introduce positively charged trimethylammonium groups by reaction with glycidyltrimethylammonium chloride (GTMAC) allowed for direct attachment of mammalian MG-63 cells, without addition of protein modifiers, or ligands. Very small increases in the surface charge resulted in significant increases in cell attachment: at a degree of substitution (DS) of only 1.4\%, MG-63 cell attachment was \textgreater 90 compared to tissue culture plastic, whereas minimal attachment occurred on unmodified cellulose. Cell attachment plateaued above DS of ca. 1.85 reflecting a similar trend in surface charge, as determined from ζ-potential measurements and capacitance coupling (electric force microscopy). Cellulose film stiffness was modulated by cross linking with glyoxal (0.3–2.6 degree of crosslinking) to produce a range of materials with surface shear moduli from 76 to 448 kPa (measured using atomic force microscopy). Cell morphology on these materials could be regulated by tuning the stiffness of the scaffolds. Thus, we report tailored functionalised biomaterials based on cationic cellulose that can be tuned through surface reaction and glyoxal crosslinkin+g, to influence the attachment and morphology of cells. These scaffolds are the first steps towards materials designed to support cells and to regulate cell morphology on implanted biomaterials using only scaffold and cells, i.e. without added adhesion promoters. [less ▲]

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See detailSurface modified cellulose scaffolds for tissue engineering
Courtenay, James C.; Johns, Marcus A.; Galembeck, Fernando et al

in Cellulose (2016)

We report the ability of cellulose to support cells without the use of matrix ligands on the surface of the material, thus creating a two-component system for tissue engineering of cells and materials ... [more ▼]

We report the ability of cellulose to support cells without the use of matrix ligands on the surface of the material, thus creating a two-component system for tissue engineering of cells and materials. Sheets of bacterial cellulose, grown from a culture medium containing Acetobacter organism were chemically modified with glycidyltrimethylammonium chloride or by oxidation with sodium hypochlorite in the presence of sodium bromide and 2,2,6,6-tetramethylpipiridine 1-oxyl radical to introduce a positive, or negative, charge, respectively. This modification process did not degrade the mechanical properties of the bulk material, but grafting of a positively charged moiety to the cellulose surface (cationic cellulose) increased cell attachment by 70 compared to unmodified cellulose, while negatively charged, oxidised cellulose films (anionic cellulose), showed low levels of cell attachment comparable to those seen for unmodified cellulose. Only a minimal level of cationic surface derivitisation (ca 3 degree of substitution) was required for increased cell attachment and no mediating proteins were required. Cell adhesion studies exhibited the same trends as the attachment studies, while the mean cell area and aspect ratio was highest on the cationic surfaces. Overall, we demonstrated the utility of positively charged bacterial cellulose in tissue engineering in the absence of proteins for cell attachment. [less ▲]

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