Navigation Links
Sticking power of plant polyphenols used in new coatings
Date:8/22/2013

A simple kitchen sink experiment helped Northwestern University researchers discover that green tea leaves not only can be used to steep a good cup of tea, but they make an excellent antibacterial coating, too.

And so can red wine, dark chocolate and cacao beans, they found. It's the powerful and healthful polyphenols at work in a new way. (Polyphenols are naturally occurring molecules found in plants whose functions include structural support and defense against bacteria and oxidative damage.)

Polyphenols are sticky, and the researchers exploited this useful property, while also retaining some of the compounds' well-known biological properties. They made new multifunctional coatings based on tannic acid and pyrogallol -- inexpensive compounds resembling the more complex polyphenols found in tea, wine and chocolate.

Simply dissolving polyphenol powder in water with the proper dash of salt quickly produces colorless coatings that have antioxidant properties, are non-toxic and can kill bacteria on contact.

The coatings -- which can stick to virtually anything, including Teflon -- could be used on a wide range of consumer, industrial and medical products, from catheters and orthopedic implants to membranes for water purification and materials used in food processing, packaging and preparation.

The study is published today (Aug. 22) in the journal Angewandte Chemie.

"We discovered a way to apply coatings onto a variety of surfaces that takes advantage of the sticky properties of the polyphenol compounds," said Phillip B. Messersmith, who led the research. "It's a very simple dip-coating process, and the antibacterial and antioxidant properties are preserved in the coating."

One could take a stainless-steel hip implant, he said, apply the process to it, and the coating that emerges spontaneously and with no other modifications will kill bacteria and quench reactive oxygen species, such as free radicals.

Messersmith is the Erastus O. Haven Professor of Biomedical Engineering at Northwestern's McCormick School of Engineering and Applied Science.

Messersmith's team tested all kinds of materials -- medically relevant polymers, engineering polymers, metals, inorganic substrates and ceramics -- and a coating stuck to each one. The researchers also demonstrated they can easily modify the coatings to give them additional functions, such as an antifouling property to prevent cells from building up on a surface, such as a pacemaker.

"What's interesting is that the raw materials we regularly encounter in our diets can benefit us in a way we had never envisioned -- as coatings on medical devices," said Tadas S. Sileika, a graduate student in Messersmith's lab and first author of the paper.

"The coatings innately have properties that are very beneficial to saving lives and keeping people healthy. Without any further modification, they can help prolong the life of a medical device, reduce inflammation in a patient and prevent bacterial infections," he said.

For 15 years, Messersmith's lab has been developing new biomedical materials, including another coating called polydopamine, also based on phenols, which are found in the sticky glue that marine mussels use to stick to rocks. Because of their chemical similarities, Messersmith and his colleagues wondered if the phenol compounds found in plant-derived red wine, green tea and dark chocolate might have similar sticking power.

This curiosity led to the kitchen sink experiments in which the researchers detected a colorless residue left behind on containers exposed to green tea and red wine. Experiments using polyphenol-rich food extracts from green tea, red wine, dark chocolate and cacao beans also produced coatings.

Messersmith and his team then went one step farther: after finding this behavior also holds for low-cost polyphenols and similar compounds, they developed a simple method for producing the multifunctional coatings.

They found that immersing objects into a saline solution of tannic acid or pyrogallol results in spontaneous coating deposition, just like what happened with the extracts and beverages. Using these inexpensive precursors instead of the extracts improves the speed and lowers the cost of the process, increasing its commercial viability, the researchers said.

"The stickiness of plant polyphenols is behind the so-called astringency effect that people can experience when drinking red wine high in tannins," Messersmith said. "The tannins stick to, or bind, saliva proteins, producing the sensation of puckering and dryness. We've put this stickiness to work in a novel way."

Polydopamine has shown great promise as a biomedical coating, but the plant polyphenol-based coatings can trump it in two important ways: The plant polyphenol-based coatings are colorless, so they don't alter a material's optical properties, and the compounds used to produce them are roughly 100 times cheaper. And that's in addition to their innate antibacterial and antioxidant properties.

The coatings also are only between 20 and 100 nanometers thick, depending on the material being coated, so would not alter biomedical instruments in a negative way.


'/>"/>

Contact: Megan Fellman
fellman@northwestern.edu
847-491-3115
Northwestern University
Source:Eurekalert

Related biology news :

1. Why sticking around is sometimes the better choice
2. Heart-powered pacemaker could one day eliminate battery-replacement surgery
3. MIT research: The power of being heard
4. Green Oakley Cluster to double OSC computing power
5. Powerful sequencing technology decodes DNA folding pattern
6. The power of broccoli, in a capsule
7. Folding light: Wrinkles and twists boost power from solar panels
8. New study discovers powerful function of single protein that controls neurotransmission
9. Powerful new approach to attack flu virus
10. UTMB researchers create powerful new method to analyze genetic data
11. Pitcher plant uses power of the rain to trap prey
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:1/28/2016)... Synaptics (NASDAQ: SYNA ), a leading developer of human interface ... 31, 2015. --> --> ... percent compared to the comparable quarter last year to $470.5 million. ... million, or $0.93 per diluted share. --> ... of fiscal 2016 grew 9 percent over the prior year period ...
(Date:1/22/2016)... 2016 http://www.researchandmarkets.com/research/4lmf2s/global_behavioral ... the  "Global Behavioral Biometric Market 2016-2020" ... http://www.researchandmarkets.com/research/4lmf2s/global_behavioral ) has announced the ... Market 2016-2020"  report to their offering. ... http://www.researchandmarkets.com/research/4lmf2s/global_behavioral ) has announced the addition ...
(Date:1/20/2016)... , Jan. 20, 2016   MedNet Solutions ... the entire spectrum of clinical research, is pleased to ... MedNet,s significant achievements are the result of the company,s ... iMedNet eClinical , it,s comprehensive, easy-to-use and ... --> Key MedNet growth achievements in ...
Breaking Biology News(10 mins):
(Date:2/5/2016)... , Feb. 5, 2016 Australian-US drug discovery and ... today the appointment of a new Chairman, Mr John ... , effective immediately. James Garner , has ... Director and former Acting CEO, Mr Iain Ross , ... Director. --> James Garner , has also been ...
(Date:2/4/2016)... , ... February 04, 2016 ... ... presented by Bloomsburg University’s Digital Forensics Club, takes place February 5-6 at ... event features 20+ speakers and activities such as workshops and competitions for ...
(Date:2/4/2016)... , Feb. 4, 2016 ContraVir Pharmaceuticals, Inc. ... the development and commercialization of targeted antiviral therapies, announced ... Investor Conference 2016, to be held February 8-9, 2016, ... Group,s 2016 Disruptive Growth & Healthcare Conference, taking place ... 10-11, 2016. James Sapirstein , Chief Executive ...
(Date:2/4/2016)... (PRWEB) , ... February 04, 2016 , ... Many of ... for over 10 years. What sets them apart from other cuvette manufacturers is ... posted on their website. On top of this steady flow of inside information, ...
Breaking Biology Technology: