Ever heard of gold quantum needles?

The initial progression of growing gold nano clusters. Structure determined by X-ray crystallography

You may have heard about gold needles, but what about gold quantum needles? Researchers at the University of Tokyo just discovered the geometric structures of these so-called quantum needles during the process of growing gold nanoclusters. These needles are not only fascinating, but they also have the potential to enable significantly higher-resolution imaging in the biomedical industry in the future.

Because gold nanoclusters have unique properties, their presence in modern nanotechnology is quite prevalent. Specifically, they react to near-infrared light, which could enhance biomedical imaging because infrared light penetrates tissues deeper compared to visible light. Due to their tiny size, scientists have to grow, or synthesize, these nanoclusters. In its most basic form, this bottom-up process involves reducing (or adding electrons) gold precursor ions in the presence of stabilizing ligands (to essentially prevent excessive growth). A common challenge with such sythesizing processes is that it can be hard to fully control the geometric shape and composition of these nanoclusters. In response to this, Shinjiro Takano, Yuya Hamasaki, and Tatsuya Tsukuda set out to understand the initial stages of gold nanocluster synthesization which they believed would set the stage for new synthesis techniques to develop the desired nanoclusters.

Using uniques growing conditions, the scientists found that these nanoclusters grew anisotropically, or at different rates in different directions. This was when the scientists first discovered these quantum needles, composed of triangular trimers on top of tetrahedral tetramers, which is where the name came from. As for the word "quantum", the scientists added this because these needles showed quantized behavior, that is, the electrons in the nanoclusters could only exibit specific potential energies.

The discovery of the uniquely-shaped nanoclusters was something "far beyond our imagination," according to Tsukuda. The geometric structures captured during the synthesization process is another step towards fully understanding how these nanoclusters grow. Tsukuda hopes that, along with the help of other experts, this new information will bring us closer to using these needles in a medical setting.

Read more: https://www.sciencedaily.com/releases/2025/09/250905180734.htm