Gold nanoprisms (NPrs) exhibit localized surface plasmon resonance (LSPR) which can be tuned by controlling the size and the aspect ratio of the nanoparticles. Tuning the LSPR of NPrs across the near-infrared region of the spectrum has opened the door for their use as biomedical tools in the so called biological window, the range of wavelength at which the absorbance of biological tissues is highly decreased.<br/>However, the synthesis of anisotropic gold nanoparticles is more challenging than their isotropic counterparts and requires low concentrations with soft reductants. A variety of capping agents or templates are used to favor shape selectivity but the most successful approach involves the toxic surfactants cetyltrimethylammonium bromide (CTAB) or chloride (CTAC) as templates. The toxicity of those additives poses a serious limitation for biomedical applications such as in optoacoustic imaging or in photothermal treatment of tumours.<br/>CTAB-free methods for the preparation of gold NPrs are not easily scalable and provide low selectivity as a large amount of spherical nanoparticles (NSs) is produced too. Separation methods reported to remove the nanospheres are time consuming and only affordable at very low scale.<br/>Recently we reported a CTAB-free synthetic method of gold NPrs in which a Au(III) solution is treated with sodium thiosulfate and potassium iodide to yield a mixture of NPrs and NSs. In this work we present a scalable separation method in which the addition of glutathione (GSH) leads to the quantitative selective precipitation of gold NPrs. The combination of the synthetic and purification protocols allows tuning the LSPR band of the gold NPrs with good overall yields. The NPrs can be easily redispersed, coated with other stabilizing agents such as poly(ethylene glycol) (PEG) and further functionalized for targeting. Noteworthy, resulting NPrs-GSH-PEG are not internalized by Vero cells as opposed to our previous NPrs-PEG, which paves the way to their use in applications in which selectivity and targeting are crucial.

Surfactant-free synthesis and purification of gold nanoprisms

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.