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Detecting plasticisers in drinks

07 Oct 2011

A simple red-to-purple colour change test could detect food or drinks contaminated with phthalates, say Chinese scientists.

Phthalates are used as plasticisers in some types of plastic food packaging; however, due to their toxicity, there are strict rules to prevent them leaching into food or drinks, or being used directly as food additives. In spite of this, there have been several recent scandals where phthalates have entered the food chain.

The analytical test proposed by Bang-Ce Ye and his team from East China University of Science and Technology, Shanghai, uses gold nanoparticles modified with uridine 5′-triphosphate to detect the phthalates. In the presence of phthalates and Cu2+, the modified gold nanoparticles are cross-linked together with the phthalates, forming a bridge between different nanoparticles. The cross-linking reaction causes aggregation of the nanoparticles and the distinctive red-to-purple colour change.

The test can tell whether food or drink has been contaminated with toxic phthalates to levels of 0.5ppm, below the set safety limit of 1.5ppm

Read the full Chemistry World news story here

Link to journal Article
Rapid and sensitive colorimetric visualization of phthalates using UTP-modified gold nanoparticles cross-linked by copper(II)
Min Zhang, Yu-Qiang Liu and Bang-Ce Ye
Chem. Commun., 2011, DOI: 10.1039/c1cc14772b

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Improved DNA chips to detect pathogens

06 Oct 2011

A new probe selection method leads to better DNA chips with fewer false positives and paves the way to improved technology development.

DNA chips are now ubiquitous tools in both genomics and diagnostics, for example pathogen detection. But selecting the correct DNA molecules for immobilising onto the chips’ surface is necessary to improve the chips’ accuracy.

The improved method involves loading the DNA probes onto the surface according to length, melting temperature and specificity. The approach was used to correctly identify 19 different types of human papilloma virus and was used to analyse 1000 clinical samples, giving identical results to sequencing data obtained from the same samples.

Reference:
A generalized probe selection method for DNA chips
S B Nimse, K-S Song, J Kim, V-T Ta, V-T Nguyen and T Kim, Chem. Commun., 2011
DOI: 10.1039/c1cc15137a

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Faster acting drugs

26 Sep 2011

Ionic liquid drugs can rapidly pass through the skin and may open the way to new, more effective medicines, say scientists in Australia. They could also be a solution to some of the most significant problems in the pharmaceutical industry, they say.

Ionic liquids (ILs) are amorphous compounds consisting of a cation-anion pair. One or both of the ions can be derived from pharmaceutically active compounds to create liquid forms of the drugs, which are more stable, soluble and bioavailable than the parent compounds. In some cases, the IL shows an enhanced pharmaceutical effect over the drugs from which it is derived. Also, being amorphous, ILs could be a solution to polymorphic interconversion, where one polymorph of a drug converts to another over time, which affects its properties.

The use of ILs has been limited because they don’t readily permeate skin and other biological membranes, thought to be because they are poorly soluble in lipids. Now, Jelena Stoimenovski and Douglas MacFarlane from Monash University have identified protic ionic liquids (PILs) – in which a pharmaceutically active acid is reacted with a biocompatible base to produce salts with dual activity – that can overcome this barrier.

Pharmaceutically active protic ionic liquids can permeate rapidly through model membranes as neutral hydrogen bonded clusters

Read the full Chemistry World article here

Link to Journal Article
Enhanced membrane transport of pharmaceutically active protic ionic liquids
Jelena Stoimenovski and Douglas R. MacFarlane
Chem. Commun., 2011, Advance Article, DOI: 10.1039/C1CC14314J

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Breathe out for personalised medicine

09 Mar 2011

A method to analyse drug levels in the body could allow people with epilepsy to avoid weeks of blood tests, claim scientists from Switzerland.

Valproic acid is an anticonvulsant drug used in the treatment of epilepsy; however, in the body, the acid binds to proteins and the concentration also can be influenced by over-the-counter medicines. The variations in the concentration mean that the amount of pharmacologically relevant valproic acid needs to be carefully monitored for the first few weeks and the dosage adjusted to compensate. The concentration is normally measured using blood samples from patients, and it can take a long time for the results to come back.

Now, Renato Zenobi at the Swiss Federal Institute of Technology in Zurich and co-workers have developed a method to measure valproic acid metabolite levels in breath using electrospray mass-spectrometry.

Using a breath test, scientists can measure levels of the anticonvulsant drug valproic acid in the body to determine the correct dosage for individual patients

See Chemistry World for the full news story

Link to journal article
Real-time, in vivo monitoring and pharmacokinetics of valproic acid via a novel biomarker in exhaled breath
Gerardo Gamez, Liang Zhu, Andreas Disko, Huanwen Chen, Vladimir Azov, Konstantin Chingin, Günter Krämer and Renato Zenobi
Chem. Commun., 2011, DOI: 10.1039/c1cc10343a

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