Lab on a Chip Blog

Korean scientists have developed a fast and simple mobile phone-based device to test urine samples for common diseases in developing countries. This could provide a cheap, painless solution for detecting disease in remote areas.

Dae-Sik Lee at the Electronics and Telecommunications Research Institute and colleagues developed a pocket-sized urinalysis colorimetric reader capable of sending data wirelessly via a smart phone. To take urine samples, the team used a commercially available 10-parameter urinalysis paper strip that detects glucose, protein, bilirubin, urobilinogen, ketones, nitrite, pH, specific gravity, erythrocytes and leukocytes.

Lee’s team tested the device on 1000 human urine samples and the results were comparable with those given by hospital equipment, demonstrating reliable glucose and protein analysis. It uses a colorimetric multidetection diode comprising LEDs, photodiodes and an optical splitter, which reads the colour intensity changes on the paper strips.

In remote areas of the developing world early detection and prevention of disease is rare. Portable lab on a chip devices have been developed to help combat this but many are not up to the standards required for use in such environments, as they are often expensive with high power consumption and take a long time to produce results, whereas Lee’s device can produce readings within six seconds.

The simple and easy to use handheld device could prove vital for patients in remote areas of the developing world

Read the full story here

Link to journal article
A simple and smart telemedicine device for developing regions: a pocket-sized colorimetric reader
Dae-Sik Lee, Byoung Goo Jeon, Chunhwa Ihm, Je-Kyun Park and Mun Yeon Jung, Lab Chip, 2011
DOI: 10.1039/c0lc00209g

Microfluidics can be used to trap a single DNA-enzyme complex in its native state for real-time analysis without having to immobilise the DNA or the enzyme, claim US researchers.

Enzymes called restriction enzymes are used to chop up DNA at specific points called recogition sites, making them useful tools in biochemistry. To anayse how they recognise and cleave DNA, the enzyme or DNA needs to be immobilised on a glass slide, but this can modify their properties, and make it difficult to analyse the products. To combat this, Susan Muller and Weilin Xu at the University of California, Berkeley, pre-bound a restriction enzyme to DNA, and fed it through a microfluidic system. This trapped the complex, and then stretched it out. Adding Mg2+ then activated the enzyme, cleaving the DNA, and permitting analysis of the products.

Ron Larson, a chemical engineering expert at the University of Michigan, Ann Arbor, US, says: ‘this work represents a novel and elegant use of fluidics to trap and stretch single DNA molecules without interference by surfaces.’ He adds that ‘the “look Ma, no hands” approach pursued by Xu and Muller has a number of advantages, not least of which is the ability to recover cleavage products for further study.’

Molecular configuration image showing the trapping, stretching and subsequent cleavage of DNA

Read the full story here

Link to journal article
Exploring both sequence detection and restriction endonuclease cleavage kinetics by recognition site via single-molecule microfluidic trapping
Weilin Xu and Susan J. Muller, Lab Chip, 2011
DOI: 10.1039/c0lc00176g