Analyst Blog

(a) Capacitor array biochip immobilized with viable E. coli and (b) response of E. coli and surface charge distribution under the applied AC electrical frequency.

Javed H. Niazi and colleagues from Sabanci University, Turkey, have developed a new capactitive biochip capable of detecting cellular stress caused by chemicals thanks to immobilised bacteria.

The biosensor works by using non-Faradaic electrochemical impedance spectroscopy to monitor changes in surface capacitance which occur when chemicals, such as acetic acid and hydrogen peroxide, disrupt the membrane function of the immobilised E. coli cells.

One referee described it as a “canary in a coal mine chip”.

The team still have some challenges to overcome but once properly developed, it could potentially be used as a cytotoxicity indicator.

It’s a must-read for anyone involved in drug, food and water safety research and will be free to access until 1st July.

Probing chemical induced cellular stress by non-Faradaic electrochemical impedance spectroscopy using an Escherichia coli capacitive biochip
Anjum Qureshi, Yasar Gurbuz and Javed H. Niazi
Analyst
DOI: 10.1039/C1AN15202E

Because of their use in food producing animals, the risk of occurrence of unwanted residues in edible products exists.

Read this critical review from our sister journal, Analytical Methods,  on sample preparation methods for the determination of veterinary residues in food matrices by porous monolith microextraction-based techniques. Several porous monolith microextraction formats, including in-tube solid-phase extraction, stir bar sorptive extraction and stir rod sorptive extraction modes, are described.  One referee commented that the review will be ‘a very useful guide for future study and application of correlative techniques.’

This is an important area of research as veterinary drugs are regularly administered via drinking water and feed with the aim of hindering the spread of disease amongst animals.  However, even low levels of these drugs, including antibiotics and pesticides, can cause health issues in humans.

You can access the critical review for free until 28th June.

Methods of sample preparation for determination of veterinary residues in food matrices by porous monolith microextraction-based techniques
Fang Wei and Yu-Qi Feng
Anal. Methods, 2011
DOI: 10.1039/C1AY05079F

Why not take a look at some of the papers we’ve published this year on veterinary drug residue analysis

Semi-targeted residue screening in complex matrices with liquid chromatography coupled to high resolution mass spectrometry: current possibilities and limitations
Anton Kaufmann, Patrick Butcher, Kathryn Maden, Stephan Walker and Miryam Widmer
Analyst, 2011, 136, 1898-1909
DOI: 10.1039/C0AN00902D

Assessment of terahertz spectroscopy to detect antibiotic residues in food and feed matrices
Albert Redo-Sanchez, Gerard Salvatella, Regina Galceran, Eva Roldós, José-Antonio García-Reguero, Massimo Castellari and Javier Tejada
Analyst, 2011, 136, 1733-1738
DOI: 10.1039/C0AN01016B

High-throughput chemical residue analysis by fast extraction and dilution flow injection mass spectrometry
Sergio C. Nanita
Analyst, 2011, 136, 285-287
DOI: 10.1039/C0AN00720J

And one more from Analytical Methods:

Development and validation (according to the 2002/657/EC regulation) of a method to quantify sulfonamides in porcine liver by fast partition at very low temperature and LC-MS/MS
Renata Pereira Lopes, Daniella Vasconcellos Augusti, Leonardo Francisco de Souza, Flávio Alves Santos, Josefa Abucater Lima, Eugênia Azevedo Vargas and Rodinei Augusti
Anal. Methods, 2011, 3, 606-613
DOI: 10.1039/C0AY00587H

Read this critical review for the theoretical background of dielectric barrier discharges (DBD) and an introduction to the application of DBD in analytical chemistry.  DBD refers to a kind of gas discharge in which plasma is separated from one or two electrodes by a dielectric barrier.

In contrast to usual discharges with direct current, the plasma is separated from one or two electrodes by a dielectric barrier. This gives rise to two main features of the dielectric barrier discharges: it can serve as a dissociation and excitation device and as an ionization mechanism, respectively.

One referee commented that ‘as a discharge method at ambient pressure and using low power, the DBD is becoming increasingly attractive in various areas of analytical chemistry.’

Dielectric barrier discharges in analytical chemistry

The paper will be free to access to until 1st June.

Dielectric barrier discharges in analytical chemistry
C. Meyer, S. Müller, E. L. Gurevich and J. Franzke
Analyst
DOI: 10.1039/C0AN00994F

The potential of microchip electrophoresis for the rapid and highly sensitive analysis of mRNA expression in cells by using a Cy5-labeled antisense riboprobe in the RNA protection assay has been shown by researchers from Japan.

Shouki Yatsushiro and colleagues from National Institute of Advanced Industrial Science and Technology (AIST), Takamatsu, show that results can be obtained in 120 seconds, using the same amount of riboprobe as used in the conventional method, with eight-times more sensitive detection of mRNA.

Read the article for free using the link below:

Ribonuclease protection assay on microchip electrophoresis
Yuka Yamaguchi, Shouki Yatsushiro, Shohei Yamamura, Hiroko Abe, Kaori Abe, Masahiro Watanabe, Kazuaki Kajimoto, Yasuo Shinohara, Yoshinobu Baba and Masatoshi Kataoka
Analyst, 2011, Advance Article
DOI: 10.1039/C0AN01044H

An improved method for diagnosing colorectal cancer without using invasive techniques has been developed by scientists in China.  A team led by Guohua Zhou at Nanjing University used a bead-based assay in conjunction with PCR to detect the RNA produced by cancer cells.

Read David Barden’s news piece in Chemistry World or access the full article for free using the link below.  What impact do you think this methodology will have for diagnostics in the future?  Leave your comments below.

Digital analysis of the expression levels of multiple colorectal cancer-related genes by multiplexed digital-PCR coupled with hydrogel bead-array
Zongtai Qi, Yinjiao Ma, Lili Deng, Haiping Wu, Guohua Zhou, Tomoharu Kajiyama and Hideki Kambara
Analyst, 2011, Advance Article
DOI: 10.1039/C0AN00976H

The results preliminarily revealed that modifications of metabolism and associated pathways accounted for metabolic perturbation of the rats that was induced by indomethacin.

Read this HOT paper which combines the use of high-throughput mass spectrometry based metabolomics and ingenuity pathway analysis, a powerful chemomatric approach, to address drug side-effects.   By using differentiated global metabolic profiling of urine to phenotype the side effects of indomethacin on specific tissue systems it will elucidate the harmful effects of indomethacin in the kidney and liver, a key obstacle to widening the clinical use of the drug.

The paper will be free to access to until 24th May.

Metabolomic analysis characterizes tissue specific indomethacin-induced metabolic perturbations of rats
Haitao Lv, Lian Liu, Gustavo Palacios and Xi Chen
Analyst, 2011, Advance Article
DOI: 10.1039/C1AN15126F