Study On The Preparation And Properties Of Functional Multilayer Films By Layer-by-Layer Self-assembly

The layer-by-layer self-assembly?Lb L?is a simple and powerful method used for functional thin film fabrications.By changing the chemical composition of the film,the surface morphology,physicochemical properties and functional properties of the film can be manipulated.Currently,integration of various specific functional materials into the layer-by-layer assemblies has become a hot research topic in the field of membrane materials.In preparation of high mechanical strength multilayer hybrid films,lamellar Na⁺MTM and spherical nano CaCO₃ were chosed as inorganic minerals.The organic/inorganic hybrid multilayer films were constructed by Na⁺MTM or CaCO₃ with polyelectrolytes,such as polyethylene?BPEI?,polypropylene acid?PAA?and carboxymethyl cellulose?CMC?,which were driven by electrostatic interaction.We designed assembly system of?BPEI/Na⁺MTM?_n,?BPEI/PAA/BPEI/Na⁺MTM?_n and?BPEI/CMC-CaCO₃?_n.The results showed that the organic/inorganic films with Na⁺MTM as inorganic components had very high mechanical strength.The Young's modulus of?BPEI/Na⁺MTM?_n was 16.6Gpa,and the transverse tensile Modulus was obtained to be about 11.0GPa,while the Young's modulus of?BPEI/PAA/BPEI/Na⁺MTM?_n was nearly 11.46Gpa.Unexpectedly,the transverse tensile Modulus of?BPEI/CMC-CaCO₃?_n was only about 1.5MPa,.which indicated that the mechanical strength was poor.Meanwhile,we made use of graphene oxide?GO?with characteristics of lamellar structure,high specific surface area and negatively charges in preparation of drug coating.A stable hybrid system of was designed by complex formation between GO and positively charged antibacterial peptide G?IIKK?₄I-NH₂?G₄?.Then a degradable antibacterial coating?Polymer?/PAA/G₄-GO/PAA?_n with a pH-responsive biodegradable poly-amino ester?polymer??and PAA through layer-by-layer self-assembly was constructed.Compared with directly assembling of G₄ into the coating of?Polymer?/PAA/G₄/PAA?_n,such G₄-GO hybrids greatly increased the loading amount of G₄ in the?Polymer?/PAA/G₄-GO/PAA?_n LBL films.We found it had great antibacterial effect for both Escherichia coli and S.saurus,but the antibacterial effect of?Polymer?/PAA/G₄/PAA?_n was not obvious.Meanwhile,we studied the drug release kinetics of the coating by UV-vis spectroscopy.The results showed that the release of G₄ from multilayer films of?Polymer?/PAA/G₄-GO/PAA?_n was basically reached equilibrium after 300min,the concentration of antimicrobial peptides in the hydrolysate was 69.37?M,and the release amount of G₄per unit area from the quartz plate was 65.30?g/cm².This research had solved the problem that the small molecule drugs or short peptides were difficult to be assembled into the films by layer-by-layer self-assembly,which provides a new idea for the preparation of controlled drug release system.