Benefits of Silica-coated Gold Nanoparticles

Improved Thermodynamic Stability for Better Data Quality and Consistent Results:

Silica-coating of gold nanoparticles facilitates efficient and uniform transfer of heat from the particles to the surrounding medium. Under pulsed laser irradiation used in photoacoustics, two-photon luminescence, and other hybrid imaging modalities, silica coated gold nanorods resist melting and maintain their shape. Therefore, they can be used repeatedly as contrast agents that maintain signal and imaging contrast enhancement, dramatically improving the quality and reproducibility of imaging research conducted using this stable product.

Signal Strength for Enhanced Imaging Quality:

Silica coating of gold nanoparticles enhances the photoacoustic signal of gold nanorods by at least 3 fold over that of unmodified gold nanoparticles, making them a highly valued product in the optoacoustic/photoacoustic imaging community. Our silica-coated gold nanoparticles can be imaged with high signal to noise ratios at greater depths within tissue maximizing sensitivity and specificity.

Figure 1: (a) Ultrasound, (b) photoacoustic, and (c) combined ultrasound and photoacoustic images (top to bottom) of inclusions containing (I) PEGylated gold nanorods and gold−silica core−shell nanorods with (II) 6 nm silica coating, (III) 20 nm silica coating, and (IV) 75 nm silica coating (left to right). Each image covers a 6 mm by 6 mm field of view. Source: Silica-Coated Gold Nanorods as Photoacoustic Signal Nanoamplifiers. Yun-Sheng Chen, Wolfgang Frey, Seungsoo Kim, Pieter Kruizinga, Kimberly Homan, and Stanislav Emelianov, Nano Letters 2011 11 (2), 348-354 (reprinted with permission).

Bioconjugation Potential for Molecular Targeting:

The silica shell presents hydroxyl groups that can be used for subsequent bioconjugation steps and molecular targeting with antibodies and other ligands.

Increased Colloidal Stability for Longer Shelf Life:

In comparison to CTAB coated gold nanoparticles, the negative zeta potential of silica-coated gold nanorods and nanospheres affords them more colloidal stability with longer shelf lives, reducing risk of waste for customers and improving cost-effectiveness.

Stable optical properties for broader applications including multiplexing:

Interactions with cells such as molecular targeting of cell receptors or endocytosis cause non-coated nanoparticles to aggregate, changing their optical properties. Silica shelled gold nanoparticles maintain their optical properties while interacting with cells, allowing researchers to expand contrast applications to multiplex imaging in cell cultures and in vivo that is problematic with uncoated gold nanorods.

Theranostic Capability facilitating use as carriers:

The silica shell can be loaded with drugs, dyes, or other labeling molecules to make the particles enhance multi-modality imaging or for theranostic applications.

PEGylated silica-coated gold nanoparticles:

When encapsulated by a PEG coating, silica-coated gold nanoparticles provide all the above advantages along with benefits associated with PEGylated gold nanoparticles such as higher colloidal stability and lower immunonogenicity.

Check out our tech spotlight on the Sigma-Aldrich website for more information about silica-coated gold nanoparticles and additional applications in life sciences & material sciences. 

Please contact us to discuss applications, our silica-coated gold nanoparticles, or for custom inquires.