NanoProbes – Not all that is gold glitters

We all know the famous saying “All that glitters is not gold”, but did you know that gold doesn’t always glitter? In fact, gold is not even golden at times! A bit of a contradiction, but it is precisely this contradiction what makes gold so interesting for its use in a wide range of applications.

When gold is reduced in size to the nano-level, the optical properties of the material change, providing gold nanoparticles with varied colours depending on their size. In this way, you can find solutions of colloidal nanogold of red, purple and blue colour depending on the size, and also the shape, of the gold particles in suspension. This particular characteristic of metallic nanoparticles is due to what is known as the Localised Surface Plasmon Resonance (LSPR), which occurs due to the resonance between the oscillating electrons at the surface of the metallic nanoparticles and the electromagnetic field of the incident light.

Oscillation of the surface electrons in metallic nanoparticles with an external electromagnetic field, due to the LSPR. From Wikipedia Commons.

And while Shakespeare may not have known that not all gold glitters when he wrote what would become the famous saying, gold nanoparticles of different colours have been used for decorative purposes in glasses and ceramics since ancient times. One of the most remarkable examples of the use of nanoparticles for this purpose is the Lycurgus Cup, a goblet made of dichroic (changing colour) glass due to the presence of gold and silver nanoparticles as well as copper.

The Lycurgus Cup (4th century AD). From Wikipedia Commons.

In more recent times, however, and due to the surge of nanotechnology as a new branch of science, the use of gold nanoparticles has been in high demand in a variety of fields that expand from photovoltaics and electronics to biomedical applications, such as imaging, therapy or drug delivery.

The wide applicability and versatility of gold nanoparticles are due to the ease with which their size, shape and surface can be tuned to the desired application. Especially useful for biomedical applications is the possibility of surrounding the nanoparticles with a variety of coatings and tags that allows these particles to not only be biocompatible with different biological mediums but also to target and link to specific biomolecules for their study. Thiols, phosphines and amines display a high affinity for gold surfaces which allows the production of a wide array of gold conjugates. In turn, these functional groups in the gold conjugates can be used to anchor additional moieties such as oligonucleotides, proteins, and antibodies. This versatility in surface functionalisation means an increase in selectivity and sensitivity and it opens up a wide range of options for gold nanoparticles.

Our supplier, Nanoprobes, know how to take advantage of the unique properties of gold nanoparticles and they provide a wide range of gold nanoparticles to suit many of your biomedical needs. They offer great options to help you to image samples through EM, X-ray or fluorescence imaging, while also providing gold nanoparticles conjugated to a variety of biomolecules for their use in multiple biomedical applications. See the table below for the link to Nanoprobes products.

And don’t hesitate to contact us if you would like more information about Nanoprobes!

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