Improvement of Stability and Cell Adhesion Properties of Polyelectrolyte Multilayer Films by Chemical Cross-Linking

Abstract

Poly(L-lysine)/hyaluronan (PLL/HA) films were chemically cross-linked with a water soluble carbodiimide (EDC) in combination with a N-hydroxysulfo-succinimide (NHS) to induce amide formation. Fourier transform infrared spectroscopy confirms the conversion of carboxylate and ammonium groups into amide bonds. Quartz crystal microbalance-dissipation reveals that the cross linking reaction is accompanied by a change in the viscoelastic properties of the films leading to more rigid films. After the cross-linking reaction, both positively and negatively ending films exhibit a negative zeta potential. It is shown by fluorescence recovery after photobleaching measured by confocal laser scanning microscopy that cross-linking dramatically reduces the diffusion of the PLL chains in the network. Cross linking also renders the films highly resistant to hyaluronidase, an enzyme that naturally degrades hyaluronan. Finally, the adhesion of chondrosarcoma cells on the films terminating either with PLL or HA is also investigated. Whereas the non cross-linked films are highly resistant to cell adhesion, the cells adhere and spread well on the cross-linked films.

Polyelectrolyte Multilayer Films of Controlled Stiffness Modulate Myoblast Cell Differentiation

“…As one carboxylic group forms a covalent amide bond with one amine group, the overall charge density in the film bulk should decrease, whereas the film surface should remain negative (due to the remaining free carboxylic groups). This was indeed verified by zeta potential measurements [23] .…”

“…For film cross-linking (CL), we followed a protocol using the water soluble carbodiimide, 1-Ethyl-3-(3-Dimethylamino-propyl)Carbodiimide (EDC) and N-Hydrosulfosuccinimide (sulfo-NHS) (both purchased from Sigma, St Quentin-Fallavier, France) [23] (EDC varying from 2 to 100 mg/mL and sulfo-NHS being fixed at 11 mg/mL).…”

“…First, their bulk and surface chemistry can be modulated by carefully choosing the type of polymer used in the buildup and the film end-layer [19] [20] [21] . Second, their "bulk" mechanical properties can be modulated, either by incorporation of nanocolloids in the films [22] , building films at different pH for a given polycation/polyanion pair [11] , or covalently cross-linking the films using [23] . Using the carbodiimide chemistry, we recently prepared a wide range of films of increased stiffness by simply varying the cross-linker concentration [24] .…”

Biodegradation-Resistant Multilayers Coated with Gold Nanoparticles. Toward a Tailor-made Artificial Extracellular Matrix

“…It is powerful technique for the fabrication of polymer-based multilayer films with dimensions from nano to micro, adjusted composition, and tunable cellular response. [5][6][7][8][9][10][11] Control over cellular functions such as adhesion, differentiation, and proliferation, 12-15 along with reservoir properties for a variety of biomolecules such as proteins, growth factors, genes, and drugs 7, 16-20 makes these films an attractive platform for cell-based applications.Despite the evident biological potential to employ the multilayers to recapitulate ECM, 3 the options to tune multilayer biodegradability are mostly limited to multilayer chemical 13,[21][22] that can significantly change multilayer properties. There is also a lack in understanding the mechanism of biomolecule-multilayer interaction that obviously defines biomolecule presentation/release from multilayers to cells and, as a result, cellular response.…”

The Synthesis of Carboxymethyl Chitosan-Pectin Film as Adsorbent for Lead (II) Metal

“…As a positively charged polysaccharide, chitosan has been incorporated with pectin to fabricate various composite materials [12] and [13]. In addition to ionic interactions, there are other types of interactions that can form between amino groups and carboxyl groups, such as hydrogen bonds and covalent bonds formed using specific conjugating chemicals, like 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS) [14].…”