Lab on a Chip Blog

This Communication from Nathan B. Crane (University of South Florida) et al. describes new method of droplet transport, combining diode-like conduction and electrowetting on dielectric to achieve continuous electrowetting with a single electrode.

Continuous electrowetting via electrochemical diodes
Christopher W. Nelson, Corey M. Lynch and Nathan B. Crane
Lab Chip, 2011, 11, 2149-2152
DOI: 10.1039/C1LC20196D

In their paper Seok Chung (Korea University) et al. have developed a hydrogel incorporating a microfluidic platform which can mimic the 3D tissue microenvironment for the study of endothelial cell sprouting angiogenesis.  They are able to precisely control the gradient of soluble angiogenic factors, VEGF and ANG-1 and obtain a quantitative response to the assay.

In vitro 3D collective sprouting angiogenesis under orchestrated ANG-1 and VEGF gradients
Yoojin Shin, Jessie S. Jeon, Sewoon Han, Gi-Seok Jung, Sehyun Shin, Sang-Hoon Lee, Ryo Sudo, Roger D. Kamm and Seok Chung
Lab Chip, 2011, 11, 2175-2181
DOI: 10.1039/C1LC20039A

William C. Messner (Carnegie Mellon University) and colleagues have also been working in 3D to achieve dynamic control of 3D chemical patterns in a single 2D microfluidic platform.  They are able to switch between ‘focused’ and ‘defocused’ 3D flow profiles, and to rapidly tune the patterns through feedback control of the inlet pressures.

Dynamic control of 3D chemical profiles with a single 2D microfluidic platform
YongTae Kim, Sagar D. Joshi, Lance A. Davidson, Philip R. LeDuc and William C. Messner
Lab Chip, 2011, 11, 2182-2188
DOI: 10.1039/C1LC20077A

As with all our HOT papers, these are free to access for 4 weeks

In their recent paper Ryan Bailey and colleagues at the University of Illinois at Urbana-Champaign address the challenge of creating a biomarker assay capable of spanning a clinically relevant dynamic range.  The ability to accurately detect protein biomarkers over a wide dynamic range is extremely important to determine the stage a disease is at, as well as monitoring the effects of any treatments.

They have developed a a silicon photonic microring resonator-based platform that can quantify the cardiovascular risk biomarker C-reactive protein over a dynamic range of six orders of magnitude.  The 3 step assay increases the dynamic range beyond that possible for a single-step assay and also reduces false positive results.

Download the article for the details – the article is currently free to access:

Sensitive on-chip detection of a protein biomarker in human serum and plasma over an extended dynamic range using silicon photonic microring resonators and sub-micron beads
Matthew S. Luchansky, Adam L. Washburn, Melinda S. McClellan and Ryan C. Bailey
Lab Chip, 2011, 11, 2042-2044
DOI: 10.1039/C1LC20231F

Cells labelled with magnetic nanoparticles are useful for a number of applications, ranging from MRI to drug delivery and cancer therapy, and being able to sort said cells based on their magnetic nanoparticle loading is obviously necessary. Continuous flow methods currently exist for separating cells based on the extent of their magnetisation, but only for cells where the nanoparticles have been bound to them via specific surface markers.

Photograph of the microfluidic magnetophoresis chip

In this paper Claire Wilhelm (University of Paris Diderot) and Nicole Pamme (University of Hull) make use of the other mechanism of introducing nanoparticles to the cells  – exploiting the natural ability of monocytes and macrophages to engulf molecules. The team produced a free-flow microfluidic chip with an external magnet to separate the cells through five different exits, depending on the loading of magnetic nanoparticles. They demonstrated successful and efficient separation of the monocytes and macrophages, with monocytes displaying a much weaker endocytotic ability than macrophages, at rates of 10 to 100 cells per second.

For the full details download the article – it’s free to access for 4 weeks:

Cell sorting by endocytotic capacity in a microfluidic magnetophoresis device
Damien Robert, Nicole Pamme, Hélène Conjeaud, Florence Gazeau, Alexander Iles and Claire Wilhelm
Lab Chip, 2011, Advance Article
DOI: 10.1039/C0LC00656D