Mobile phone scanner detects harmful bacteria

The scientists published their findings in the latest edition of the Royal Society of Chemistry journal Analyst.

Outbreaks of E. coli pose a huge threat to health, especially in developing countries. Most strains of E. coli are harmless but some strains however, such as enterohaemorrhagic E. coli (EHEC), can cause severe foodborne disease, according to the World Health Organisation. E. coli is transmitted to humans primarily through consumption of contaminated foods, such as raw or undercooked ground meat products, raw milk and contaminated raw vegetables and sprouts.

As existing detection devices are often expensive and complex, an accurate and efficient detection device could be extremely popular. There are more than five billion mobile phones on the planet and 70 per cent of these are in the developing world. 

Hongying Zhu and colleagues at the University of California, Los Angeles, developed a device able to take advantage of this technology. Zhu told the RSC's Chemistry World magazine: "Our cell phone based platform would be very useful to bring advanced technologies to remote and resource poor locations" adding that the phone provides "a ubiquitous platform for conducting advanced micro-analysis wherever cell phones work." 

The device consists of glass capillary tubes with light emitting diode (LED) lights on either end. E. coli antibodies are fixed to the sides of the capillaries and trap any E. coli present in a liquid sample. Secondary antibodies and quantum dots are then added to the capillaries and these bind to the trapped E. coli, capturing the bacteria in a sandwich complex. 

The LED lights excite the quantum dots, causing them to emit fluorescent light. The light emission is captured by the phone camera as pictures of the capillaries are taken approximately once a second.   

The team tested the device using water samples and milk and were able to selectively detect low concentrations of E. coli, even in the presence of other bacteria species. Zhu intends to develop the device so one phone could be used to detect different bacteria. 

More information: Quantum dot enabled detection of Escherichia coli using a cell-phone, H Zhu, U Sikora and A Ozcan, Analyst, 2012, DOI: 10.1039/c2an35071h

Provided by Royal Society of Chemistry

Study finds common fire retardant harmful to aquatic life

A new study by Baylor University environmental health researchers found that zebra fish exposed to several different technical mixtures of polybrominated diphenyl ethers (PBDEs) – a common fire retardant – during early development can cause developmental malformations, changes in behavior and death.

The study will appear in the June issue of the journal Environmental Toxicology and Chemistry and is the first to test multiple PBDE mixtures for changes in behavior, physical malformations and mortality on zebra fish.

PBDEs are found in many common household products from blankets to couches to food wrappers. Lab tests have shown that PBDEs have been found in human breast milk and cord blood. Previous studies have showed children with high levels of PBDEs in their umbilical cord at birth scored lower on tests between one and six years of age. In 2006, the state of California started prohibiting the use of PBDEs.

The family of PBDEs consists of more than 200 possible substances, which are called congeners. Congeners are considered low if they average between 1 to 5 bromine atoms per molecule.

The Baylor researchers tested six PBDE congeners for developmental effects on embryonic zebra fish. Changes in behavior, physical malformations and mortality were recorded daily for seven days.

The results showed:
Lower brominated congeners were more toxic than higher brominated congeners.
Embryos were most sensitive to two particular types of PBDE exposures, the two lowest brominated congeners of the six tested. Both induced a curved body axis and eventually death.
In all, four of the six congeners tested caused developmental malformations, such as a curved body axis and pulmonary edema. Five of the six caused alterations in behaviors, such as decreased swimming rates and increased spontaneous movement in the embryo. "While most PBDEs have either been banned or phased out throughout the world, it may be more beneficial to identify congeners of concern rather than replacing these compounds with chemicals of unknown biological interactions," said Dr. Erica Bruce, assistant professor of environmental science at Baylor who is an expert in environmental chemicals and their effects on public health. "Alterations in early behavior may potentially be due to disruption of thyroid hormones. Thyroid hormones play a vital role in the development of the cholinergic system and this study gives insight into biological interaction within a few hours of exposure. The observed hyperactivity may be due to overstimulation of the cholinergic system," Bruce said.

Provided by Baylor University

Simple method of dealing with harmful radioactive iodine discovered

A novel way to immobilise radioactive forms of iodine using a microwave, has been discovered by an expert at the University of Sheffield.

Iodine radioisotopes are produced by fission of uranium fuel in a nuclear reactor. Radioactive iodine is of concern because it is highly mobile in the environment and selective uptake by the thyroid gland can pose a significant cancer risk following long term exposure. Furthermore, iodine-129, which is a type of radioactive iodine, has an extremely long half life of 15.7 million years, so is one of the most significant long term hazards faced by the population due to its emission during the geological disposal of nuclear waste.

Professor Neil Hyatt, from the University's Department of Materials Science and Engineering, has now found a way of locking up iodine radioisotopes in a durable, solid material suitable for ultimate disposal, like lead iodovanadinite(Pb5(VO4)3I). The research, which was published in the Journal of Nuclear Materials, demonstrates how his simple, inexpensive and rapid method can be done at atmospheric pressure.

Professor Hyatt and his team created a solid material for immobilisation of iodine with the formula Pb5(VO4)3I, by heating a mixture of lead iodide, lead oxide and vanadium oxide.

Previously, this has only been achieved using high pressure and a sealed container, because iodine is volatilised at high temperature. However, using the knowledge that vanadium is a good absorber of microwaves at 2.45 GHz – the frequency used in domestic microwave ovens – the team were able to heat the mixture of chemicals in a microwave oven to produce Pb5(VO4)3I in about three minutes.

The key to the method's success is that Pb5(VO4)3I is a poor absorber of 2.45 GHz microwaves, so once this is formed, the sample cannot absorb microwaves, so the temperature does not get high enough for the iodine to volatilise.

Iodine-131 was the harmful gas emitted from the Fukushima power plant in Japan following the earthquake and tsunami last month, and was a significant contributor to the health effects from open-air atomic bomb testing in the 1950s, and was also emitted during the Chernobyl disaster. It is hoped the new research will reduce the public health impact associated with the release of radioactive iodine to the environment by providing a simple and inexpensive method of immobilisation in a solid material, which could be rapidly deployed in an accident scenario.

Professor Neil Hyatt, said: "In spent nuclear fuel, the iodine is not immobilised, so once the containment is breached it simply gets dispersed. At present, iodine-129 released by nuclear fuel reprocessing is discharged direct to the Irish Sea off the coast of Sellafield. Substantial quantities of this radioisotope were also released into the sea off the coast of Japan in the Fukushima incident. Our new method offers a way of safely and rapidly containing this radionuclide, reducing the potential long term impact on human health from discharge to the environment."

More information: Rapid synthesis of Pb5(VO4)3I, for the immobilisation of iodine radioisotopes, by microwave dielectric heating, doi:10.1016/j.jnucmat.2011.04.041

Abstract
Rapid synthesis of Pb5(VO4)3I, a potential immobilisation host for iodine radioisotopes, was achieved in an open container by microwave dielectric heating of a mixture of PbO, PbI2, and V2O5 at a power of 800 W for 180s (at 2.45 GHz). The resulting ceramic bodies exhibited a zoned microstructure, differentiated by inter-granular porosity and phase assemblage, as a consequence of the inverse temperature gradient characteristic of microwave dielectric heating. Liquid PbI2 within the interior of microwave processed ceramics assisted formation of Pb5(VO4)3I, and reduced inter-granular porosity. In contrast, the exterior of microwave processed ceramics comprised poorly sintered Pb5(VO4)3I with the presence of minor reagent relics. Quantitative microanalysis, electron diffraction and Rietveld analysis, confirmed the synthesis of stoichiometric Pb5(VO4)3I within precision. The crystal structure of Pb5(VO4)3I was found to adopt space group P63/m with a = 10.4429(3) A and c = 7.4865(2) A.

Provided by University of Sheffield

Common fire retardant harmful to aquatic life

ScienceDaily (May 24, 2011) — A new study by Baylor University environmental health researchers found that zebra fish exposed to several different technical mixtures of polybrominated diphenyl ethers (PBDEs) -- a common fire retardant -- during early development can cause developmental malformations, changes in behavior and death.

The study will appear in the June issue of the journal Environmental Toxicology and Chemistry and is the first to test multiple PBDE mixtures for changes in behavior, physical malformations and mortality on zebra fish.

PBDEs are found in many common household products from blankets to couches to food wrappers. Lab tests have shown that PBDEs have been found in human breast milk and cord blood. Previous studies have showed children with high levels of PBDEs in their umbilical cord at birth scored lower on tests between one and six years of age. In 2006, the state of California started prohibiting the use of PBDEs.

The family of PBDEs consists of more than 200 possible substances, which are called congeners. Congeners are considered low if they average between 1 to 5 bromine atoms per molecule.

The Baylor researchers tested six PBDE congeners for developmental effects on embryonic zebra fish. Changes in behavior, physical malformations and mortality were recorded daily for seven days.

The results showed:

Lower brominated congeners were more toxic than higher brominated congeners.Embryos were most sensitive to two particular types of PBDE exposures, the two lowest brominated congeners of the six tested. Both induced a curved body axis and eventually death.In all, four of the six congeners tested caused developmental malformations, such as a curved body axis and pulmonary edema. Five of the six caused alterations in behaviors, such as decreased swimming rates and increased spontaneous movement in the embryo.

"While most PBDEs have either been banned or phased out throughout the world, it may be more beneficial to identify congeners of concern rather than replacing these compounds with chemicals of unknown biological interactions," said Dr. Erica Bruce, assistant professor of environmental science at Baylor who is an expert in environmental chemicals and their effects on public health. "Alterations in early behavior may potentially be due to disruption of thyroid hormones. Thyroid hormones play a vital role in the development of the cholinergic system and this study gives insight into biological interaction within a few hours of exposure. The observed hyperactivity may be due to overstimulation of the cholinergic system," Bruce said.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Baylor University.

Journal Reference:

Crystal Y. Usenko, Eleanor M. Robinson, Sascha Usenko, Bryan W. Brooks, Erica D. Bruce. PBDE developmental effects on embryonic zebrafish. Environmental Toxicology and Chemistry, 2011; DOI: 10.1002/etc.570

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

Student creates clothes that trap harmful gases

 A new Cornell cloth that can selectively trap noxious gases and odors has been fashioned by a senior into a mask and hooded shirts inspired by the military.

The garments use metal organic framework molecules (MOFs) and cellulose fibers that were assembled in assistant fiber science professor Juan Hinestroza's lab to create the special cloth.

MOFs, which are clustered crystalline compounds, can be manipulated at the nanolevel to have cages that are the exact same size as the gas they are trying to capture, said Jennifer Keane '11, a fiber science and apparel design (FSAD) major in the College of Human Ecology.

Keane worked with Hinestroza and fiber science postdoctoral associate Marcia Da Silva Pinto to create the gas-absorbing hood and mask. Some of the basic science behind this project was funded by the U.S. Department of Defense.

"The initial goal of attaching the MOFs to fibers was sponsored by the Defense Threat Reduction Agency. We wanted to harness the power of these molecules to absorb gases and incorporate these MOFs into fibers, which allows us to make very efficient filtration systems," Hinestroza said.

Da Silva Pinto first created MOF fabrics in Hinestroza's lab, working in collaboration with chemists from Professor Omar Yaghi's group at the University of California-Los Angeles; Yaghi is one of the pioneers and leaders of MOF chemistry, said Hinestroza.

At first the process did not work smoothly. "These crystalline molecules are like a powder that cannot easily become part of cloth," Da Silva Pinto noted. After months of trying to attach the particles to the fiber, the researchers realized that, "The key was to bring the fiber to the particle ... It was a real paradigm shift," she said.

"Now we can make large surfaces of fabric coated with MOFs, and we are looking at scaling up this technology to nanofibers," said Hinestroza. "This type of work would only be possible at a place like Cornell where you have this unique merging of disciplines, where a fashion designer can interact easily with a chemist or a materials scientist."

Though trained as a chemical engineer, Hinestroza said he likes "to work with designers because they think very differently than scientists. I love that because that's where the real creativity comes, when you have this collision of styles and thinking processes."

Keane, who took Hinestroza's Textiles, Apparel and Innovation class, said she started Cornell as a pre-med major but switched to FSAD because she enjoyed the creative aspect of sewing and designing her own clothing in high school. She has since interned with Nike and recently received a job offer from Adidas.

She noted that while her MOF hood and mask will not be showcased in the upcoming Cornell Fashion Collective spring fashion show at Barton Hall, April 16, 7-9:30 p.m., her line of comfortable women's sportswear will be. It includes many geometric patterns and bright jewel tones.

"It's a lot of knits, jersey and this brushed denim, which is really soft ... It was based off of jewelry designs that I saw in Italy," she said.

Provided by Cornell University (news : web)