Concentration Dependent Effect of Quaternary Amines on the Adhesion of U251-MG Cells

Abstract

Cationic gels have seen increasing interest in recent years for 2D cell cultivation since they may represent an alternative to the well-known RGD-peptide motif functionalized gels. However, few hydrogel systems with adjustable cationic strength have been fabricated and investigated so far. In this work, eight gels with defined concentrations of cationic groups, two of which also contained the RGD peptide, were prepared from three well-defined, soluble precursor copolymers with thiol-functionalities and PEGDA3500 as a crosslinker via thiol-ene chemistry. Live/dead stainings of U-251-MG cells on the hydrogels with different concentrations of the cationic motif were made after 3 days and 7 days of cultivation. The results show a high dependence of the number of adhesive cells and their morphology, cluster versus spread cells, on the concentration of cationic groups in the gel. This effect was more pronounced when the gels were not further dialyzed before usage. In addition, a synergistic effect of the two motifs, cationic group and RGD peptide, could be demonstrated, which together induce stronger cell adhesion than either motif alone.

Cationic Hydrogels Modulate Neural Stem and Progenitor Cell Proliferation and Differentiation Behavior in Dependence of Cationic Moiety Concentration in 2D Cell Culture

“…As described and characterized by Stamm et al, these hydrogels G1 to G6 possessed Young’s moduli ranging from 7.7 ± 0.4 to 11.1 ± 0.4 kPa. Because of different concentrations of the cationic molecule TMAEA, the ζ-potential of the positively charged hydrogels varied from +20.0 ± 1.2 ( G2 ) to +42.1 ± 3.7 mV ( G6 ), whereas the unmodified hydrogel G1 exhibited a ζ-potential of −3.9 ± 1.6 mV as published in a previous study . The hydrogels were dialyzed in water before cell seeding.…”

“…Recently, we have developed a synthetic hydrogel system with focus on being able to vary the concentration of cationic charge with only a small change in hydrogel stiffness. For this purpose, two precursor polymers, a hydrophilic, neutral one with free thiol groups P1 and a second one with 38 mol % permanent cationic TMAEA moieties and free thiol groups P2 , were prepared by free radical polymerization . The subsequent hydrogel formation was carried out by cross-linking with PEGDA 3500 and Michael addition between the acrylate functionalities and the thiol groups.…”

“…More recently, we have developed a synthetic hydrogel system based on 4-acryloylmorpholine (AMor), N,N'-bis(methacryloyl)cystamide (BMAC), and trimethylaminoethyl acrylate (TMAEA) as cationic moiety and PEGDA 3500 as cross-linker. 27 The main advantage of the system is that hydrogels can be fabricated by mixing welldefined copolymer precursors to form gels with a cationic group concentration ranging from 0.06 to 0.91 μmol/mg polymer. Moreover, we demonstrated that the adhesion of neural cells was promoted by a higher concentration of cationic molecule TMAEA.…”

“…■ MATERIALS AND METHODS Hydrogels. Hydrogels were prepared from two BMAC-containing prepolymers that included additionally on the one hand the hydrophilic monomer AMor and on the other hand AMor and the cationic molecule TMAEA as described and characterized previously by Stamm et al 27 Hydrogels of the desired cationic concentration were formed by mixing a neutral copolymer with a cationic copolymer at different proportions and subsequently using the thiol−ene Michael reaction between the thiol moieties from BMAC and the cross-linker PEGDA 3500 . By this procedure, six gels, enumerated from gel 1 to gel 6 (G1−G6), with different cationic concentrations were produced.…”

“…Scheme 1. Fabrication of Hydrogels G1−G6 from Precursor Copolymers P1, P2, and PEGDA 3500 (Concentration of Functional Groups in Brackets)27 ACS Biomaterials Science & Engineering…”