by Staff Writers
Houston TX (SPX) May 26, 2017
Scientists at Rice University and Ben-Gurion University of the Negev (BGU) have discovered that laser-induced graphene (LIG) is a highly effective anti-fouling material and, when electrified, bacteria zapper.
LIG is a spongy version of graphene, the single-atom layer of carbon atoms. The Rice lab of chemist James Tour developed it three years ago by burning partway through an inexpensive polyimide sheet with a laser, which turned the surface into a lattice of interconnected graphene sheets. The researchers have since suggested uses for the material in wearable electronics and fuel cells and for superhydrophobic or superhydrophilic surfaces.
According to their report in the American Chemical Society's ACS Applied Materials and Interfaces, LIG also protects surfaces from biofouling, the buildup of microorganisms, plants or other biological material on wet surfaces.
"This form of graphene is extremely resistant to biofilm formation, which has promise for places like water-treatment plants, oil-drilling operations, hospitals and ocean applications like underwater pipes that are sensitive to fouling," Tour said. "The antibacterial qualities when electricity is applied is a great additional benefit."
When used as electrodes with a small applied voltage, LIG becomes the bacterial equivalent of a backyard bug zapper. Tests without the charge confirmed what has long been known - that graphene-based nanoparticles have antibacterial properties. When 1.1 to 2.5 volts were applied, the highly conductive LIG electrodes "greatly enhanced" those properties.
Under the microscope, the researchers watched as fluorescently tagged Pseudomonas aeruginosa bacteria in a solution with LIG electrodes above 1.1 volts were drawn toward the anode. Above 1.5 volts, the cells began to disappear and vanished completely within 30 seconds. At 2.5 volts, bacteria disappeared almost completely from the surface after one second.
The Rice lab partnered with Professor Christopher Arnusch, a lecturer at the BGU Zuckerberg Institute for Water Research who specializes in water purification. Arnusch's lab tested LIG electrodes in a bacteria-laden solution with 10 percent secondary treated wastewater and found that after nine hours at 2.5 volts, 99.9 percent of the bacteria were killed and the electrodes strongly resisted biofilm formation.
The researchers suspect bacteria may meet their demise through a combination of contact with the rough surface of LIG, the electrical charge and toxicity from localized production of hydrogen peroxide. The contact may be something like a knee hitting pavement, but in this case, the bacteria are all knee and the sharp graphene edges quickly destroy their membranes.
Fortunately, LIG's anti-fouling properties keep dead bacteria from accumulating on the surface, Tour said.
"The combination of passive biofouling inhibition and active voltage-induced microbial removal will likely make this a highly sought-after material for inhibiting the growth of troublesome natural fouling that plagues many industries," Tour said. Research paper
Madrid, Spain (SPX) May 18, 2017
Energy dissipation is a key ingredient in understanding many physical phenomena in thermodynamics, photonics, chemical reactions, nuclear fission, photon emissions, or even electronic circuits, among others. In a vibrating system, the energy dissipation is quantified by the quality factor. If the quality factor of the resonator is high, the mechanical energy will dissipate at a very low ra ... read more
Carbon Worlds - where graphite, diamond, amorphous, fullerenes meet
|The content herein, unless otherwise known to be public domain, are Copyright 1995-2017 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. All articles labeled "by Staff Writers" include reports supplied to Space Media Network by industry news wires, PR agencies, corporate press officers and the like. Such articles are individually curated and edited by Space Media Network staff on the basis of the report's information value to our industry and professional readership. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement|