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"Layer-by-Layer Self-Assembly for Nanocoating and Drug Encapsulation"

Relatore: Yuri Lvov- Institute for Micromanufacturing and Biomedical Engineering Program,

Aula Newton
25 Maggio 2005 ore 17.00

Nanocoating: Layer-by-layer (LbL) self-assembly of molecularly organized films was developed with linear polyions, nanoparticles, dye and proteins. The formation of alternate outermost layers of the opposite charge at every adsorption cycle is the key point of the procedure. An alternate assembly of linear polyanions and polycations typically provides 1-2 nm growth step for a bilayer, and a number of bilayers, which can be built up, is from one to few hundreds. Protein Architecture: LbL-buildup by alternation of linear polyions and over 25 different proteins was elaborated. Enzymes in the films preserved bioactivity. Film-superlattices containing ordered layers of more than one protein species were constructed. Multi-enzymatic sequential reactions with directed transfer of products were realized. Micropatterns: A layer-by-layer nanoassembly (LbL) was used in combination with traditional microlithography to develop patterns in ordered 100 nm thick nanoparticle multilayers. Using this process, materials with specific cell adhesion and biocompatibility properties can be patterned to achieve specific cell attachment and proliferation. This has been demonstrated using rat aortic smooth muscle cells as a model system. Current studies are focusing on developing this process on different optically transparent substrates to achieve novel cell study environments and to produce novel cell-based sensors. Nanoorganized Microcapsules: An LbL-assembly of organized enzymatic shells on nanocores (or loading hollow polyion shells with enzymes) allows fabrication of catalytic “bionanoreactors”, as it was demonstrated for glucose oxidase, catalase, peroxidase, and urease ensembles. An introducing magnetic nanoparticle interlayer to such reactors allows manipulation with these bio/colloids (such as their removal or stirring). The polyion shell formation via the layer-by-layer assembly allows replication of biological object, such as cells and viruses. Polymer micro and nanocapsules were prepared using as template inorganic microcrystals (which were dissolved later). Different enzymes and insulin were loaded in such capsules. Polyphenols and polypeptides were synthesized via biocatalysis in the capsule nanoconfined volume. An assembly of 20-50 nm organized polymer shells on drug microcrystals (Furosemide, Dexamethasone, Insulin) allowed their sustained controlled release.