Lab on a Chip Blog

In recent years methicillin-resistant Staphylococcus aureus (MRSA) has become one of the most prevalent antibiotic resistant pathogens in hospitals and as such there is an urgent need for a way of rapidly detecting it to limit the spread of the infection.

Current methods of detection, involving the use of PCR, require quite bulky, power-intensive and quite expensive apparatus. Gwo-Bin Lee et al. have developed a portable hand-held system where the entire diagnostic protocol, from bio-sample pre-treatment to optical detection, can be automatically completed within an hour and with a limit of detection 1000- fold higher than conventional bench-top PCR systems.

The entire process can be accomplished automatically via magnetic bead-based hybridization of the target DNA purified from clinical samples, a loop-mediated isothermal amplification process for the amplification of the target genes, and then spectrophotometric analysis of the amplified target genes.

To find out more take a look at this HOT article which is FREE to view for 4 weeks!

A magnetic bead-based assay for the rapid detection of methicillin-resistant Staphylococcus aureus by using a microfluidic system with integrated loop-mediated isothermal amplification
Chih-Hung Wang, Kang-Yi Lien, Jiunn-Jong Wu and Gwo-Bin Lee
Lab Chip, 2011, 11, 1521-1531
DOI: 10.1039/C0LC00430H

Antiretroviral therapy (ART) increases the longevity and quality of life for HIV patients.  The lack of objective diagnostic tests to determine when to start ART and to monitor its successes hinders the effective use of treatment.  An important diagnostic procedure is to obtain a patient’s CD4+ lymphocyte count, which is traditionally carried out using optical instrumentation. However, the cost and technical requirements of such equipment make them infeasible as analytical methods in poorer countries.

William Rodriguez (Daktari Diagnostics) and Rashid Bashir (University of Illinois) present a solution to this problem with their novel microfabricated biochip to enumerate CD4+ T lymphocytes from healthy human subject blood samples.

Their biochip incorporates electrical impedance sensing coupled with immunoaffinity chromatography to electrically differentiate CD4+ cells from other leukocytes with accuracy comparable to current optical diagnostic methods.  This negates any requirement for labelling or optical detection, while its microfabricated nature suggests it may be an inexpensive, simple and portable alternative to current flow cytometric practises.

Learn more about this device by reading this HOT article, which is free to access for the next 4 weeks!

A microfabricated electrical differential counter for the selective enumeration of CD4+ T lymphocytes
Nicholas N. Watkins, Supriya Sridhar, Xuanhong Cheng, Grace D. Chen, Mehmet Toner, William Rodriguez and Rashid Bashir
Lab Chip, 2011, 11, 1437-1447
DOI: 10.1039/C0LC00556H

In drug discovery it is important to know as early as possible whether a potential drug candidate forms toxic metabolites or not.  Normally, each drug candidate must be evaluated by extensive in vitro metabolism experiments however these are generally time-consuming and expensive.

Scientists in Finland, however, have developed a microchip to mimic phase I metabolic reactions of low-molecular weight compounds.  Raimo Ketola and colleagues at the University of Helsinki have designed an integrated TiO₂ nanoreactor/ionisation chip with UV radiation and direct MS analysis to produce and identify photocatalysed reaction products of selected drug molecules.

This enables rapid on-line analyses which have shown remarkable consistency with metabolites obtained from other in vivo and in vitro methods.  It is hoped that this technique, with its rapid prediction of phase I metabolites, will speed up the discovery of new potential drug candidates.

This HOT article is available to download, free of charge, for the next 4 weeks – careful, don’t burn your fingers!

Integrated photocatalytic micropillar nanoreactor electrospray ionization chip for mimicking phase I metabolic reactions
Teemu Nissilä, Lauri Sainiemi, Mika-Matti Karikko, Marianna Kemell, Mikko Ritala, Sami Franssila, Risto Kostiainen and Raimo A. Ketola
Lab Chip, 2011, Advance Article
DOI: 10.1039/C0LC00689K

A platform capable of seamlessly unifying both optoelectrowetting and optoelectronic tweezers has been developed by Justin Valley and co-workers from the Berkeley Sensor and Actuator Center.

The device requires no lithographically defined microelectrodes as it uses light patterning to define the electrodes, which means that manipulation of droplets and the particles within these droplets can occur anywhere on the device surface. Switching between manipulating droplets to manipulating the particles in those droplets is merely a case of altering an externally applied electric frequency.

Learn more about the device by reading this HOT article, which is free to access for the next 4 weeks!

A unified platform for optoelectrowetting and optoelectronic tweezers
Justin K. Valley, Shao NingPei, Arash Jamshidi, Hsan-Yin Hsu and Ming C. Wu
Lab Chip, 2011, Advance Article
DOI: 10.1039/C0LC00568A

Reverse transcriptase PCR (RT-PCR) has been introduced as the most sensitive method for detecting and pathotyping the avian influenza virus (AIV) or ‘bird flu’, however the number of targets that can be amplified in a single run is limited.

Now chemists at the Technical University of Denmark have developed a device for the rapid and unambiguous detection of AIV by integrating DNA microarray-based solid-phase PCR on to a microfluidic chip. This combines the advantages of microfluidic devices, the high-throughput capabilities of microarrays and the superior specificity of solid-phase PCR. The whole process takes under an hour and uses a sample volume 10 times less than anything previously, meaning that this device can be widely employed by veterinarians for rapid on-site screening of AIV in wild and domestic poultries.

Find out more by reading this HOT article, which is free to access for the next 4 weeks!

A lab-on-a-chip device for rapid identification of avian influenza viral RNA by solid-phase PCR
Yi Sun, Raghuram Dhumpa, Dang Duong Bang, Jonas Høgberg, Kurt Handberg and Anders Wolff
Lab Chip, 2011, Advance Article
DOI: 10.1039/C0LC00528B

Isolating biological or biochemical content in aqueous droplets within an immiscible oil medium on a microfluidic device allows samples to be transported without cross-contamination or dispersion.  But generating droplets at a suitably high speed with precise volume control has been a challenge.

Now Pei-Yu Chiou and Sung-Yong Park from UCLA have developed a pulse laser-driven droplet mechanism that allows droplet formation of up to 10000 droplets per second with controllable volumes between 1-150 pL and >1% volume variation.

Their device (shown below) consists of two microfluidic channels connected by a nozzle-like opening. A highly focused intense laser pulse induces a rapidly expanding cavitation bubble to push the nearby water into the oil channel for droplet formation.

This HOT article is free to access until the end of March – so download it today and see how they did it!

High-speed droplet generation on demand driven by pulse laser-induced cavitation
Sung-Yong Park, Ting-Hsiang Wu, Yue Chen, Michael A. Teitell and Pei-Yu Chiou
Lab Chip, 2011, 11, 1010-1012
DOI: 10.1039/C0LC00555J