Preparation of [Amine-Terminated Generation 5 Poly(amidoamine)]--Poly(lactic--glycolic acid) Electrospun Nanofibrous Mats for Scaffold-Mediated Gene Transfection.

Combining biomaterial scaffolds with gene cargos for gene therapy is promising for tissue engineering. Herein, we developed a gene delivery platform through surface grafting of amine-terminated generation 5 poly(amidoamine) (PAMAM) dendrimers (G5·NH) with biodegradable electrospun poly(lactic--glycolic acid) (PLGA) nanofibers by combining layer-by-layer (LbL) electrostatic assembly technology with dendrimer chemistry. PLGA nanofibers were precoated with positively charged poly(diallydimethylammoium chloride) and poly(acrylic acid) through electrostatic interaction and then subsequently cross-linked with G5·NH dendrimer covalently through 1-ethyl-3-[3-(dimethylamino)propyl] carbodiimide hydrochloride chemistry. The successful grafting of G5·NH dendrimer on PLGA nanofibers was confirmed by X-ray photoelectron spectroscopy. Scanning electron microscopy studies show that smooth, uniform morphology of nanofibers does not significantly change after grafting of G5·NH dendrimers except for a slight increase in the fiber diameter, whereas atomic force microscopy images at a high-resolution scale indicated a slightly rough surface for PLGA nanofibers after grafting with G5·NH dendrimer. Additionally, PLGA nanofibrous scaffolds became hydrophilic after grafting with G5·NH dendrimers. Biological investigation showed that the developed G5·NH--PLGA nanofibrous scaffolds not only allowed for the attachment and proliferation of NIH 3T3 cells but also were capable of complexing pDNA and delivering pDNA/dendrimer complex for solid state gene transfection in situ. The functionalization of PLGA nanofibers with dendrimers may find diverse applications in the area of tissue engineering, gene therapy, and drug delivery.