Substrate-Independent Layer-by-Layer Assembly Using Mussel Adhesive-Inspired Polymers (27158)
Substrate independent multifunctional coatings adherent to a wide range of natural and synthetic materials including polymers, metals and oxides, providing adhesive properties without surface pretreatment. The coatings employ a simple layer by layer process for the surface attachment of organic and inorganic materials.
ADVANTAGES: A simple coating process that affords adhesive binding to most any substrate surface. The coatings developed afford effective coverage and can be utilized as a base primer to bind a vast range of materials and substrates for medical and commercial use.
SUMMARY: Layer by layer (LbL) coating techniques allow creation of multifunctional films on surfaces while maintaining bulk properties. Sequential adsorption of polymers onto surfaces from solution can provide complex multilayer films with desired properties. Coating of materials such as hydrophobic polymers (PE, PET, PTFE, etc) generally requires aggressive surface pretreatment such as plasma or chemical oxidation. This invention utilizes polymers, modeled after mussel adhesive proteins, that adhere to a range of natural and synthetic materials without the need for surface pretreatment and applied directly by LbL processes. Cationic polymers of poly(ethyleneimine) (PEI) incorporating catechol functions (PEI-C) and an anionic polymer of hyaluronic acid (HA) containing dopamine (HA-C) were created and employed as adhesive primers by LbL application. Thus PTFE, poly(tetrafluoroethylene), an anti-adhesive surface, upon three successive (PEI-C)/ (HA-C) LbL coating cycles completely sealed the surface as monitored by fluorine XPS measurement. The impact of coating is demonstrated by the reduction in wetting advancing contact angle from 115° to 28° after the 3x coating.. The (PEI-C)/ (HA-C) polymer coatings also proved effective on polyethylene (PE), polyethylene terephthalate (PET), polycarbonate (PC) and poly(methyl methacrylate) (PMMA), Au, and SiOx surfaces (Figure 1)
PEI-C also serves as an effective coating primer. A silicon wafer (SiOx) treated with PEI-C, followed by 10x LbL cycles of poly(acrylic acid)/ poly-L-lysine coating, afforded complete and uniform SiOx surface coverage. The catechol containing materials are expected to enhance coating adhesion and mechanical properties.
Reactivity of the catechol functions in PEI-C/HA-C films promote the electroless Ag and Cu metallization of these coatings. For example, a LbL film of (PEI-C/HA-C)20 assembled on SiOx, upon emersion in silver nitrate solution produced Ag nanoparticles dispersed within the LbL multilayers. The Ag containing film exhibited strong antibacterial activity when subjected to Escherichia coli versus controls (Figure 2).
This technology provides a simple method for substrate independent LbL assembly, without pretreatment, on a wide array of materials with great application potential
Phillip Messersmith, Haeshin Lee, Yuhan Lee
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