Gold nanoparticles (AuNPs) have been the focus of many studies owing to their unique optical and electronic properties and versatile applications. However, synthesis of stable and homogeneous AuNPs with a particular choice of size is still a challenge. In this study we describe a direct synthesis approach to produce stable and monodisperse water-soluble AuNPs with a tightly controlled diameter in the 1.7-2.4 nm range. We controlled the size by changing only the sodium hydroxide (NaOH) concentration in the synthesis. Gel electrophoresis, transmission electron microscopy (TEM), and solution X-ray scattering showed that the AuNPs had narrow size-distributions. We further showed that AuNPs of the different sizes were clearly distinguishable in TEM micrographs, paving the way to dual-target labeling. The reactivity of the AuNPs toward DNA and proteins was also demonstrated. We utilized this reactivity to label tail-anchored proteins embedded in the membrane of the anticancer nanodrug Doxil as a means to target it to specific cell types. The gold-labeling enabled the precise localization of the tail-anchored proteins in cryo-TEM images of the therapeutic liposomes.
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© 2019 American Chemical Society.