Polyelectrolyte layer-by-layer (LbL) films that disintegrate under physiological conditions are intensively studied as coatings to enable the release of bioactive components. Herein, we report on the interactions and pH-stability of LbL films composed of chitosan (CH) or N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (CMCH) and tannic acid (TA), employed to guarantee the film disintegration. The self-assembly of TA with CH and CMCH at pH 5 and with CMCH at pH 7.4 were proven by turbidimetric, surface plasmon resonance and UV-Vis analyses. The LbL films exhibited pH-dependent properties; CMCH/TA films prepared at pH 7.4 showed exponential growth as well as a higher layer thickness and surface roughness, whereas films prepared at pH 5 grew linearly and were smoother. The film stability varied with the pH used for film assembly; CH/TA films assembled at pH 5 were unstable at pH 8.5, whereas CMCH/TA films assembled at pH 7.4 disintegrated at pH 4. All films exhibited a similar disassembly at pH 7.4. The coatings reduced the adhesion of E. coli and S. aureus by approximately 80%. CMCH-terminated CMCH/TA films were more resistant to bacterial adhesion, whereas CH-terminated CH/TA films demonstrated stronger killing activity. The prepared pH-triggered decomposable LbL films could be used as degradable coatings that allow the release of therapeutics for biomedical applications and also prevent bacterial adhesion.

Dept of Bioactive Polymers Institute of Macromolecular Chemistry Academy of Sciences of the Czech Republic v v i Prague Czech Republic

Dept of Biological Models Institute of Macromolecular Chemistry Academy of Sciences of the Czech Republic v v i Prague Czech Republic

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