Sweet success: Nanocapsule perfectly binds sucrose in water

September 5, 2017, Tokyo Institute of Technology
Conceptual cartoon of how a bioreceptor (left) and a Yoshizawa's nanocapsule (right) bind sucrose in their cavities. Credit: Science Advances

Scientists around the world are pursuing the goal of developing synthetic receptors capable of recognizing biologically important molecules. Although many attempts have been made to mimic the way that protein pockets detect sugar dissolved in water with hydrogen bonding interactions, few have succeeded, mainly due to the interfering nature of water molecules. Now, a Japanese team of researchers has proposed a brand new approach.

"Our unique recognition system is based on special interactions—known as CH-π interactions[term1]—between sucrose and the inner walls of our nanocapsule," says Michito Yoshizawa, who co-designed the study with Masahiro Yamashina at Tokyo Institute of Technology (Tokyo Tech). "To our knowledge, nobody has harnessed the interaction for developing this type of recognition system before."

With a diameter of one nanometer (a billionth of a meter), the spherical cavity of the capsule is just the right size to catch the nearly one-nanometer-long and spherical sucrose molecule. Building on the team's previous research on molecular self-assembly, the capsule works by forming a cavity around the sucrose, which then becomes fully surrounded by multiple aromatic panels[term2] (see Figure 1).

By mixing the capsule, composed of two metal ions and four ligands[term3], with sucrose in water under mild conditions, the team obtained a sucrose-bound capsule with a high yield. Published in Science Advances, an open-access sister journal of Science, the product structure was confirmed using proton and mass spectrometry methods. Yoshizawa adds: "The capsule is easy to produce and handle, and its stability is very high."

In a series of experiments to explore how the capsule would respond to different kinds of sugar, the researchers made three observations: 1) the capsule does not interact with monosaccharides such as glucose and fructose, 2) among common disaccharides (for example, sucrose, lactose, maltose and trehalose), only sucrose was encapsulated, and thus 3) even in mixtures of two disaccharides (in so-called competitive binding experiments), the capsule bound sucrose with a 100% selectivity.

"It's usually very difficult to tell these sugars apart. For example, sucrose, lactose and maltose have the same molecular formula, meaning that they have the same number of hydrogen, oxygen and carbon atoms—only their configuration is different," says Yoshizawa. "Still, our nanocapsule was able to recognize subtle differences and exclusively capture sucrose."

The team also examined how the capsule responded to common artificial sugars: aspartame (known to be around 200 times sweeter than sucrose) and sucralose (around 600 times sweeter than sucrose). The capsule's binding preference was found to be in the order of sucralose, aspartame and , which exactly mirrors the order in which we perceive levels of sweetness.

This finding could impact the food and chemical industries by helping with the search for even sweeter compounds. If such new compounds can be found and synthesized easily, artificial sweeteners could be produced more cost-effectively than existing methods.

In future, Yoshizawa says that it may be possible to develop "designer nanocapsules" of various shapes and sizes. Ultimately, these capsules could be used for the development of new biosensor technologies in the medical and environmental fields.

Explore further: Study suggests color of sweetener packet impacts sweetness perception and liking

More information: Masahiro Yamashina et al, A polyaromatic nanocapsule as a sucrose receptor in water, Science Advances (2017). DOI: 10.1126/sciadv.1701126

Related Stories

Scientists offer sweet solution to marathon fatigue

November 30, 2015

It turns out a spoonful of sugar might not just help the medicine go down, but could also help stave off tiredness faced by weary marathon runners – or other long-distance athletes – when they hit the wall.

Recommended for you

X-ray triggered nano-bubbles to target cancer

July 16, 2018

Innovative drug filled nano-bubbles, able to be successfully triggered in the body by X-rays, have been developed by researchers, paving the way for a new range of cancer treatments for patients.

Smart window controls light and heat, kills microorganisms

July 13, 2018

A new smart window offers more than just a nice view—it also controls the transmittance of sunlight, heats the interiors of buildings by converting solar radiation into heat, and virtually eliminates E. coli bacteria living ...

Quantum dot white LEDs achieve record efficiency

July 12, 2018

Researchers have demonstrated nanomaterial-based white-light-emitting diodes (LEDs) that exhibit a record luminous efficiency of 105 lumens per watt. Luminous efficiency is a measure of how well a light source uses power ...

How gold nanoparticles could improve solar energy storage

July 12, 2018

Star-shaped gold nanoparticles, coated with a semiconductor, can produce hydrogen from water over four times more efficiently than other methods—opening the door to improved storage of solar energy and other advances that ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.