title: Cationic gold microparticles for biolistic delivery of nucleic acids.
abstract: Here we report preparation and properties of positively charged gold microparticles, and their use for biolistic DNA delivery. Micron-sized gold microparticles were modified by building self-assembling polyethylenimine monolayers on their surfaces, which enabled their electrostatic interaction with negatively charged molecules such as DNA. One milligram of the surface-modified microparticles was able to bind directly to up to 3.5 microg of DNA, exceeding the 1 microg/mg limit of the conventional protocols. The binding showed no apparent dependency on DNA purity, size, or conformation. The interaction occurred over a broad range of pH values and salt concentrations, and was stable throughout the standard protocol for biolistic cartridge preparation. At the standard 1 microg dose, biological activity of the DNA biolistically delivered on the charge-modified gold was 25% higher than that delivered on conventional microparticles. Loading the charge-modified gold with more DNA stimulated proportionally higher gene expression. The charge-modified gold can be also used for delivery of small biological molecules such as siRNA. Tissue culture cells biolistically transfected with a LUC+ specific siRNA showed 80% reduction of Luc expression relative to those cells transfected with an irrelevant siRNA. Along with its superior properties as a DNA delivery vehicle, charge-modified gold offers a unique opportunity to deliver various DNA formulations in addition to traditional naked DNA.
authors.affiliation: Center for Innovations in Medicine, The Biodesign Institute at Arizona State University, Tempe, AZ 85287, USA.
authors.forename: Sergei
authors.initials: S
authors.lastname: Svarovsky
authors.forename: Alexandre
authors.initials: A
authors.lastname: Borovkov
authors.forename: Kathryn
authors.initials: K
authors.lastname: Sykes
mesh_terms: D000818:Animals; D019470:Biolistics / Q000379:methods*; D002412:Cations; D004247:DNA / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008156:Luciferases / Q000378:metabolism; D053768:Metal Nanoparticles / Q000737:chemistry*; D051379:Mice; D041681:NIH 3T3 Cells; D009696:Nucleic Acids / Q000235:genetics*; D010316:Particle Size; D011094:Polyethyleneimine / Q000737:chemistry; D034741:RNA, Small Interfering / Q000378:metabolism; D055672:Static Electricity; D014162:Transfection
chemical_list: D002412:Cations; D009696:Nucleic Acids; D034741:RNA, Small Interfering; D006046:Gold; D011094:Polyethyleneimine; D004247:DNA; D008156:Luciferases