Tag Archives: cavities

Nano with green tea for sensitive teeth

The future will be beautiful if scientists are successful with a new DNA (deoxyribonucleic acid) sunscreen (my Aug. 3, 2017 posting) and a new dental material for people with sensitive teeth. From an Aug. 2, 2017 news item on phys.org,

An ice cold drink is refreshing in the summer, but for people with sensitive teeth, it can cause a painful jolt in the mouth. This condition can be treated, but many current approaches don’t last long. Now researchers report in the journal ACS [American Chemical Society] Applied Materials & Interfaces the development of a new material with an extract from green tea that could fix this problem—and help prevent cavities in these susceptible patients.

An Aug. 2, 2017 ACS news release, which originated the news item, describes the problem and the work in more detail,

Tooth sensitivity commonly occurs when the protective layers of teeth are worn away, revealing a bony tissue called dentin. This tissue contains microscopic hollow tubes that, when exposed, allow hot and cold liquids and food to contact the underlying nerve endings in the teeth, causing pain. Unprotected dentin is also vulnerable to cavity formation. Plugging these tubes with a mineral called nanohydroxyapatite is a long-standing approach to treating sensitivity. But the material doesn’t stand up well to regular brushing, grinding, erosion or acid produced by cavity-causing bacteria. Cui Huang and colleagues wanted to tackle sensitivity and beat the bacteria at the same time.

The researchers encapsulated nanohydroxyapatite and a green tea polyphenol — epigallocatechin-3-gallate, or EGCG — in silica nanoparticles, which can stand up to acid and wear and tear. EGCG has been shown in previous studies to fight Streptococcus mutans, which forms biofilms that cause cavities. Testing on extracted wisdom teeth showed that the material plugged the dentin tubules, released EGCG for at least 96 hours, stood up to tooth erosion and brushing and prevented biofilm formation. It also showed low toxicity. Based on these findings, the researchers say the material could indeed be a good candidate for combating tooth sensitivity and cavities.

The authors acknowledge funding from the National Natural Science Foundation of China, the Natural Science Foundation of Hubei Province of China and the Fundamental Research Funds for the Central Universities.

Here’s a link to and a citation for the paper,

Development of Epigallocatechin-3-gallate-Encapsulated Nanohydroxyapatite/Mesoporous Silica for Therapeutic Management of Dentin Surface by Jian Yu, Hongye Yang, Kang Li, Hongyu Ren, Jinmei Lei, and Cui Huang. ACS Appl. Mater. Interfaces, Article ASAP DOI: 10.1021/acsami.7b06597 Publication Date (Web): July 13, 2017

Copyright © 2017 American Chemical Society

This paper is behind a paywall.

Making the impossible possible: on demand and by design, atomic scale pipes

This research on pipes from the University of Manchester will probably never finds its way into plumbing practices but, apparently, is of great interest in fundamental research. From a Sept. 7, 2016 news item on phys.org,

Materials containing tiny capillaries and cavities are widely used in filtration, separation and many other technologies, without which our modern lifestyle would be impossible. Those materials are usually found by luck or accident rather than design. It has been impossible to create artificial capillaries with atomic-scale precision.

Now a Manchester group led by postdoctoral researcher Radha Boya and Nobel laureate Andre Geim show how to make the impossible possible, as reported in Nature.

A Sept. 7, 2016 University of Manchester press release (also on EurekAlert), which originated the news item,  provides a description of the technology,

The new technology is elegant, adaptable and strikingly simple. In fact, it is a kind of antipode of the famous material graphene. When making graphene, people often take a piece of graphite and use Scotch tape to extract a single atomic plane of carbon atoms, graphene. The remaining graphite is discarded.

In this new research, Manchester scientists similarly extracted a strip of graphene from graphite, but discarded the graphene and focused on what was left: an ultra-thin cavity within the graphite crystal.

Such atomic scale cavities can be made from various materials to achieve not only a desired size but also to choose properties of capillary walls. They can be atomically smooth or rough, hydrophilic or hydrophobic, insulating or conductive, electrically charged or neutral; the list goes on.

The voids can be made as cavities (to confine various substances) or open-ended tunnels (to transport different gases and liquids), which is of huge interest for fundamental research and many applications. It is limited only by imagination what such narrow tunnels with designer properties can potentially do for us.

Properties of materials at this truly atomic scale are expected to be quite different from those we are familiar with in our macroscopic world. To demonstrate that this is the case of their atomic-scale voids, the Manchester group tested how water runs through those ultra-narrow pipes.

To everyone’s surprise, they found water to flow with little friction and at high speed, as if the channels were many thousands times wider than they actually are.

Radha Boya commented ‘This is an entirely new type of nanoscale systems. Such capillaries were never imagined, even in theory. No one thought that this degree of accuracy in design could be possible. New filtration, desalination, gas separation technologies are kind of obvious directions but there are so many others to explore’.

Sir Andre added ‘Making something useful out of an empty space is certainly cute. Finding that this space offers so much of new science is flabbergasting. Even with hindsight, I did not expect the idea to work so well. There are myriads of possibilities for research and development, which now need to be looked at. We are stunned by the choice.’

Here’s a link to and a citation for the paper,

Molecular transport through capillaries made with atomic-scale precision by B. Radha, A. Esfandiar, F. C. Wang, A. P. Rooney, K. Gopinadhan, A. Keerthi, A. Mishchenko, A. Janardanan, P. Blake, L. Fumagalli, M. Lozada-Hidalgo, S. Garaj, S. J. Haigh, I. V. Grigorieva, H. A. Wu, & A. K. Geim. Nature (2016)  doi:10.1038/nature19363 Published online 07 September 2016

This paper is behind a paywall.