Multilayered polyelectrolyte films promote the direct and localized delivery of DNA to cells.
ABSTRACT Multilayered polyelectrolyte films fabricated from plasmid DNA and a hydrolytically degradable synthetic polycation can be used to direct the localized transfection of cells without the aid of a secondary transfection agent. Multilayered assemblies 100 nm thick consisting of alternating layers of synthetic polymer and plasmid DNA encoding for enhanced green fluorescent protein (EGFP) were deposited on quartz substrates using a layer-by-layer fabrication procedure. The placement of film-coated slides in contact with COS-7 cells growing in serum-containing culture medium resulted in gene expression in cells localized under the film-coated portion of the slides. The average percentage of cells expressing EGFP relative to the total number of cells ranged from 4.6% to 37.9%, with an average of 18.6%+/-8.2%, as determined by fluorescence microscopy. In addition to providing a mechanism for the immobilization of DNA at the cell/surface interface, a preliminary analysis of film topography by atomic force microscopy (AFM) demonstrated that polymer /DNA films undergo significant structural rearrangements upon incubation to present surface bound condensed plasmid DNA nanoparticles. These data suggest that the presence of the cationic polymer in these materials may also contribute to the internalization and expression of plasmid. The materials and design principles reported here present an attractive framework for the local or non-invasive delivery of DNA from the surfaces of implantable materials or biomedical devices.
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ABSTRACT: Herein, we describe the delivery of plasmid DNA (pDNA) using silk fibroin (SF) layer-by-layer assembled microcapsules. Deposition of fluorescently labeled SF onto polystyrene (PS) template particles resulted in increasing fluorescence intensity and decreasing surface charge in correlation to SF layer number. After removal of the PS core, hollow, monodisperse, and structurally stable SF microcapsules of variable size and shell thickness were obtained. Plasmid DNA encoding for enhanced green fluorescent protein (eGFP) was loaded onto 1 or 4 μm capsules, either by incorporation of pDNA within the innermost layer of the shell or by adsorption to the microcapsules surface, and in vitro pDNA release, cytotoxicty and eGFP expression were studied. Sustained pDNA release over 3 days was observed using both loading techniques, being accelerated in the presence of protease. DNA loaded SF microcapsules resulted in efficient cell transfection along with low cytotoxicity after 3 days incubation compared to treatment with pDNA/branched polyethylenimine complexes. Among the tested conditions highest transfection efficiencies were achieved using 1 μm capsules where pDNA was adsorbed to the capsule surface. Our results suggest that SF microcapsules are suitable for the localized delivery of pDNA, combining low cytotoxicity and high transfection efficiency.Biomaterials 06/2014; DOI:10.1016/j.biomaterials.2014.05.062 · 8.31 Impact Factor
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ABSTRACT: Layer-by-Layer (LbL) assembly is a simple and highly versatile method to modify surfaces and fabricate robust and highly-ordered nanostructured coatings over almost any type of substrate. Such versatility enables the incorporation of a plethora of building blocks, including materials exhibiting switchable properties, in a single device through a multitude of complementary intermolecular interactions. Switchable materials may undergo reversible physicochemical changes in response to a variety of external triggers. Although most of the works in the literature have been focusing on stimuli-responsive materials that are sensitive to common triggers such as pH, ionic strength, or temperature, much less has been discussed on LbL systems which are sensitive to non-invasive and easily controlled light stimulus, despite its unique potential. This review provides a deep overview of the recent progresses achieved in the design and fabrication of light-responsive LbL polymeric multilayer systems, their potential future challenges and opportunities, and possible applications. Many examples are given on light-responsive polymeric multilayer assemblies built from metal nanoparticles, functional dyes, and metal oxides. Such stimuli-responsive functional materials, and combinations among them, may lead to novel and highly promising nanostructured smart functional systems well-suited for a wide range of research fields, including biomedicine and biotechnology.Advanced Functional Materials 07/2014; 24(36):5624-5648. DOI:10.1002/adfm.201401050 · 10.44 Impact Factor