Colloidal Force Spectroscopy and Cell Biological Investigations on Biomimetic Polyelectrolyte Multilayer Coatings Composed of Chondroitin Sulfate and Heparin

Abstract

To promote osteoblast adhesion and proliferation on (bio)material surfaces, biomimetic coatings resembling the natural extracellular matrix (ECM) are desirable. The glycosamino glycans (GAGs) chondroitin sulfate (CS) and heparin (HEP) are promising candidates for a biomimetic coating since they are two of the most prevalent noncollagenous biomolecules constituting the ECM. Coatings containing CS and HEP were prepared employing the "layer by layer" technique yielding polyelectrolyte multilayers (PEMs). Physicochemical and mechanical characterization of the coatings were performed by means of streaming potential measurements and colloidal force spectroscopy. The capability of the coatings to support cell adhesion, spreading, proliferation, and maintenance of an osteoblastic phenotype was assessed with SaOS osteosarcoma cells. We demonstrate that PEMs constructed from CS as the polyanion display a low Young's modulus correlated with poorly supported cell adhesion and proliferation. When the CS was adsorbed onto a stiffer polypeptide PEM basis, the Young's modulus increased, and the cell response was significantly improved. For HEP coatings an intermediate Young's modulus and moderate cell adhesion and spreading were observed. No significant changes in stiffness or cell response were detected when HEP was adsorbed onto the polypeptide film.

Preparation and characterization of poly(l-histidine)/poly(l-glutamic acid) multilayer on silicon with nanometer-sized surface structures

“…Here, values of +15 mV and À5 mV were determined for PLL and PGA, respectively, which are found at the lower end of the spectrum of published values. A comparison of established coatings like PLL/PGA with published data [59,65,69] commonly results in deviations among all reported absolute values due to the manifold of parameters influencing measurement and data treatment.…”

“…The apparatus includes a titration unit allowing to perform automated measurement series with varied solution compositions. As electrolyte 1 mmol/L NaCl solution with pH values between 2 and 10 (adjusted by HCl and 0.1 mol/L NaOH) were applied at temperatures of 24°C ± 1.5°C with a maximum pressure difference of 300 mbar for the flow in two directions [65]. For every single measurement, at least 4 runs with 18 steps were recorded and the conductivity subsequently corrected on the basis of a final measurement with a 0.1 mol/L NaCl solution.…”

The Design of Polysaccharide Multilayers for Medical Applications

“…Multilayers formed by CS and several polycations have been studied extensively in view of potential applications in tissue engineering. Two recent studies have assessed the construction of multilayers between either CH or poly-(L-lysine) (PLL) as polycation and HA, CS, and HEP as polyanions [22,54]. Both studies stress the importance of ion pair interactions, and for PLL-based multilayers the ion pairing between the polycation increases with increasing charge density of the polyanion (HA < CS < HEP).…”

Polyelectrolyte Multilayer-Calcium Phosphate Composite Coatings for Metal Implants

“…The height of a (PLL/PGA) 10 assembly reaches approximately 100 nm (Figure 1d), which is lower than previously observed in a fluidic environment (approx 280 nm). 27 The difference may be due to the drying process employed in our experiments. Compared to the relatively regular aggregates of (PLL/PGA) n multilayers, the multilayers of (PLL/PAA) n (n = 7 and 10) and (PLL/CS) 7 created relatively large, irregular aggregates with wide size distributions (Figures 1e and 2b,c).…”