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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.