RESUMEN
Perfluorocarbon emulsion nanodroplets containing iron oxide nanoparticles (IONPs) within their inner perfluorohexane (PFH) core were prepared to investigate potential use as an acoustically activatable ultrasound contrast agent, with the hypothesis that incorporation of IONPs into the fluorous phase of a liquid perfluorocarbon emulsion would potentiate acoustic vaporization. IONPs with an oleic acid (OA) hydrophobic coating were synthesized through chemical co-precipitation. To suspend IONP in PFH, OA was exchanged with perfluorononanoic acid (PFNA) via ligand exchange to yield fluorophilic PFNA-coated IONPs (PFNA-IONPs). Suspensions with various amounts of PFNA-IONPs (0-15% w/v) in PFH were emulsified in saline by sonication, using 5% (w/v) egg yolk phospholipid as an emulsifier. PFNA-IONPs were characterized with transmission electron microscopy (TEM), transmission electron cryomicroscopy (cryoTEM), and thermogravimetric analysis (TGA) with Fourier transform infrared spectroscopy (FTIR). IONP were between 5 and 10â¯nm in diameter as measured by electron microscopy, and hydrodynamic size of the PFH nanodroplets were 150 to 230â¯nm as measured by dynamic light scattering (DLS). Acoustic droplet vaporization of PFH nanodroplets (PFH-NDs) was induced using conversion pulses (100â¯cycle at 1.1â¯MHz and 50% duty cycle) provided by a focused ultrasound transducer, and formed microbubbles were imaged using a clinical ultrasound scanner. The acoustic pressure threshold needed for PFH-NDs vaporization decreased with increasing temperature and IONP content. PFH-NDs containing 5% w/v IONP converted to microbubbles at 42⯰C at 2.18 MI, which is just above the exposure limits of 1.9 MI allowed by the FDA for clinical ultrasound scanners, whereas 10 and 15% emulsion vaporized at 1.87 and 1.24 MI, respectively. Furthermore, 5% IONP-loaded PFH-NDs injected intravenously into melanoma-bearing mice at a dose of 120â¯mg PFH/kg, converted into detectable microbubbles in vivo 5â¯h, but not shortly after injection, indicating that this technique detects NDs accumulated in tumors.
Asunto(s)
Medios de Contraste/química , Fluorocarburos/química , Nanopartículas de Magnetita/química , Melanoma/diagnóstico por imagen , Acústica , Animales , Línea Celular Tumoral , Yema de Huevo/química , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Gotas Lipídicas/química , Nanopartículas de Magnetita/administración & dosificación , Ratones , Ratones Desnudos , Microburbujas , Neoplasias Experimentales , Transición de Fase , Fosfolípidos/química , Temperatura de Transición , Ultrasonografía/métodos , VolatilizaciónRESUMEN
We present an untemplated, single-component antisense oligonucleotide delivery system capable of regulating mRNA abundance in live human cells. While most approaches to nucleic acid delivery rely on secondary carriers and complex multicomponent charge-neutralizing formulations, we demonstrate efficient delivery using a simple locked nucleic acid (LNA)-polymer conjugate that assembles into spherical micellar nanoparticles displaying a dense shell of nucleic acid at the surface. Cellular uptake of soft LNA nanoparticles occurs rapidly within minutes as evidenced by flow cytometry and fluorescence microscopy. Importantly, these LNA nanoparticles knockdown survivin mRNA, an established target for cancer therapy, in a sequence-specific fashion as analyzed by RT-PCR.