Spreading of Cell Aggregates on Zwitterion-Modified Chitosan Films

Abstract

The sulfobetaine (SB) moiety, which comprises a quaternary ammonium group linked to a negatively charged sulfonate ester, is known to impart nonfouling properties to interfaces coated with polysulfobetaines or grafted with SB-polymeric brushes. Increasingly, evidence emerges that the SB group is, overall, a better antifouling group than the phosphorylcholine (PC) moiety extensively used in the past. We report here the synthesis of a series of SB-modified chitosans (CH-SB) carrying between 20 and 40 mol % SB per monosaccharide unit. Chitosan (CH) itself is a naturally derived copolymer of glucosamine and N-acetyl-glucosamine linked with a β-1,4 bond. Analysis by quartz crystal microbalance with dissipation (QCM-D) indicates that CH-SB films (thickness ∼ 20 nm) resist adsorption of bovine serum albumin (BSA) with increasing efficiency as the SB content of the polymer augments (surface coverage ∼ 15 μg cm for films of CH with 40 mol % SB). The cell adhesivity of CH-SB films coated on glass was assessed by determining the spreading dynamics of CT26 cell aggregates. When placed on chitosan films, known to be cell-adhesive, the CT26 cell aggregates spread by forming a cell monolayer around them. The spreading of CT26 cell aggregates on zwitterion-modified chitosans films is thwarted remarkably. In the cases of CH-SB30 and CH-SB40 films, only a few isolated cells escape from the aggregates. The extent of aggregate spreading, quantified based on the theory of liquid wetting, provides a simple in vitro assay of the nonfouling properties of substrates toward specific cell lines. This assay can be adopted to test and compare the fouling characteristics of substrates very different from the chemical viewpoint.

Neural Differentiation Potential of Mesenchymal Stem Cells Enhanced by Biocompatible Chitosan-Gold Nanocomposites

“…Furthermore, Au nanoparticles can modify the surface topography of natural and synthetic polymers, conferring favorable properties at a low concentration owing to their extremely small size, i.e., at the nanoscale (5–50 nm) [ 57 ], leading to the improvement of surface physicochemical properties. The surface roughness would influence the cell aggregation due to the interaction between the nanocomposites and cells [ 58 , 59 ]. According to our AFM images ( Figure S1B ), the RMS values of the Chi–Au 50 and 100 ppm nanocomposites were 0.67 and 0.38 nm, indicating a uniform surface topography for cell aggregation.…”

Electrostatically Assembled Multilayered Films of Biopolymer Enhanced Nanocapsules for on-Demand Drug Release

“…Chitosan (CS) is a natural polysaccharide with no toxicity, good biocompatibility and high biodegradability. , Primary amino groups of CS potentiate the formation of strongly bonded LbL films with negatively charged components. Besides, the ability of this polysaccharide to swell and dehydrate depends on the composition and environment and has been exploited to facilitate a range of applications such as drug delivery vehicles and antimicrobial agents .…”