Layer by layer buildup of polysaccharide films: physical chemistry and cellular adhesion aspects.
The formation ofpolysaccharide films based on the alternate deposition of chitosan (CHI) and hyaluronan (HA) was investigated by several techniques. The multilayer buildup takes place in two stages: during the first stage, the surface is covered by isolated islets that grow and coalesce as the construction goes on. After several deposition steps, a continuous film is formed and the second stage of the buildup process takes place. The whole process is characterized by an exponential increase of the mass and thickness of the film with the number of deposition steps. This exponential growth mechanism is related to the ability of the polycation to diffuse "in" and "out" of the whole film at each deposition step. Using confocal laser microscopy and fluorescently labeled CHI, we show that such a diffusion behavior, already observed with poly(L-lysine) as a polycation, is also found with CHI, a polycation presenting a large persistence length. We also analyze the effect of the molecular weight (MW) of the diffusing polyelectrolyte (CHI) on the buildup process and observe a faster growth for low MW chitosan. The influence of the salt concentration during buildup is also investigated. Whereas the CHI/HA films grow rapidly at high salt concentration (0.15 M NaCl) with the formation of a uniform film after only a few deposition steps, it is very difficult to build the film at 10(-4) M NaCl. In this latter case, the deposited mass increases linearly with the number of deposition steps and the first deposition stage, where the surface is covered by islets, lasts at least up to 50 bilayer deposition steps. However, even at these low salt concentrations and in the islet configuration, CHI chains seem to diffuse in and out of the CHI/HA complexes. The linear mass increase of the film with the number of deposition steps despite the CHI diffusion is explained by a partial redissolution of the CHI/HA complexes forming the film during different steps of the buildup process. Finally, the uniform films built at high salt concentrations were also found to be chondrocyte resistant and, more interestingly, bacterial resistant. Therefore, the (CHI/HA) films may be used as an antimicrobial coating.
Richert
Ludovic
L
Institut National de la Santé et de la Recherche Médicale, Université Louis Pasteur, 67085 Strasbourg Cedex, France.
Lavalle
Philippe
P
Payan
Elisabeth
E
Shu
Xiao Zheng
XZ
Prestwich
Glenn D
GD
Stoltz
Jean-François
JF
Schaaf
Pierre
P
Voegel
Jean-Claude
JC
Picart
Catherine
C
D000818:Animals; D001422:Bacterial Adhesion; D001672:Biocompatible Materials / Q000138:chemical synthesis / Q000737:chemistry; D002448:Cell Adhesion; D049109:Cell Proliferation; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D048271:Chitosan / Q000737:chemistry; D019902:Chondrocytes / Q000166:cytology; D006820:Hyaluronic Acid / Q000737:chemistry; D015394:Molecular Structure; D011134:Polysaccharides / Q000138:chemical synthesis* / Q000737:chemistry*; D051381:Rats; D013499:Surface Properties
D001672:Biocompatible Materials; D011134:Polysaccharides; D006820:Hyaluronic Acid; D048271:Chitosan