The development of alternate drug delivery agents and drug scaffolds is an ongoing task in medicinal chemistry (1−3). The recent burst of research involving gold nanoparticles as transfection vectors (4−6), DNA-binding agents (7−9), protein inhibitors (10), and spectroscopic markers (11−14) demonstrates the versatility of these systems in biological applications. Gold particles display several features that make them well suited for biomedical applications, including straightforward synthesis (7), stability (15), and the facile ability to incorporate secondary tags such as peptides targeted to specific cell types to afford selectivity (16−18). These nanoparticle systems, however, have not been well evaluated to determine their interactions with cells beyond the designated functions.
Recently, we have shown that cationically functionalized mixed monolayer protected gold clusters (MMPCs) are capable of mediating DNA translocation across the cell membrane in mammalian cells at levels much higher than polyethyleneimine (PEI), a widely used transfection vector (4). At higher nanoparticle concentrations, however, transfection efficiency decreases due to cytotoxicity. While many available drugs display toxicity at sufficiently elevated concentrations (19−20), the toxicity of the nanoparticles was observed in this case at concentrations only 2-fold in excess of that found to have maximal transfection activity.
The development of alternate drug delivery agents and drug scaffolds is an ongoing task in medicinal chemistry (1−3). The recent burst of research involving gold nanoparticles as transfection vectors (4−6), DNA-binding agents (7−9), protein inhibitors (10), and spectroscopic markers (11−14) demonstrates the versatility of these systems in biological applications. Gold particles display several features that make them well suited for biomedical applications, including straightforward synthesis (7), stability (15), and the facile ability to incorporate secondary tags such as peptides targeted to specific cell types to afford selectivity (16−18). These nanoparticle systems, however, have not been well evaluated to determine their interactions with cells beyond the designated functions.Recently, we have shown that cationically functionalized mixed monolayer protected gold clusters (MMPCs) are capable of mediating DNA translocation across the cell membrane in mammalian cells at levels much higher than polyethyleneimine (PEI), a widely used transfection vector (4). At higher nanoparticle concentrations, however, transfection efficiency decreases due to cytotoxicity. While many available drugs display toxicity at sufficiently elevated concentrations (19−20), the toxicity of the nanoparticles was observed in this case at concentrations only 2-fold in excess of that found to have maximal transfection activity.
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