Online ISSN
1751-875X
Print ISSN
1751-8741
IET Nanobiotechnology
Volume 1, Issue 3, June 2007
Volumes & issues:
Volume 1, Issue 3
June 2007
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- Author(s): V.J. Sieben ; C.S. Debes Marun ; P.M. Pilarski ; G.V. Kaigala ; L.M. Pilarski ; C.J. Backhouse
- Source: IET Nanobiotechnology, Volume 1, Issue 3, p. 27 –35
- DOI: 10.1049/iet-nbt:20060021
- Type: Article
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Interphase fluorescence in situ hybridisation (FISH) is a sensitive diagnostic tool used for the detection of alterations in the genome on cell-by-cell basis. However, the cost-per-test and the technical complexity of current FISH protocols have slowed its widespread utilisation in clinical settings. For many cancers, the lack of a cost-effective and informative diagnostic method has compromised the quality of life for patients. We present the first demonstration of a microchip-based FISH protocol, coupled with a novel method to immobilise peripheral blood mononuclear cells inside microfluidic channels. These first on-chip implementations of FISH allow several chromosomal abnormalities associated with multiple myeloma to be detected with a ten-fold higher throughput and 1/10‐th the reagent consumption of the traditional slide-based method. Moreover, the chip test is performed within hours whereas the conventional protocol required days. In addition, two on-chip methods to enhance the hybridisation aspects of FISH have been examined: mechanical and electrokinetic pumping. Similar agitation methods have led to significant improvements in hybridisation efficiency with DNA microarray work, but with this cell-based method the benefits were moderate. On-chip FISH technology holds promise for sophisticated and cost-effective screening of cancer patients at every clinic visit. - Author(s): M. Lian ; N. Islam ; J. Wu
- Source: IET Nanobiotechnology, Volume 1, Issue 3, p. 36 –43
- DOI: 10.1049/iet-nbt:20060022
- Type: Article
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36
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AC electrokinetics has shown great potential for microfluidic functions such as pumping, mixing and concentrating particles. So far, electrokinetics are typically applied on fluids that are not too conductive (<0.02 S/m), which excludes most biofluidic applications. To solve this problem, this paper seeks to apply AC electrothermal (ACET) effect to manipulate conductive fluids and particles within. ACET generates temperature gradients in the fluids, and consequently induces space charges that move in electric fields and produce microflows. This paper reports two new ACET devices, a parallel plate particle trap and an asymmetric electrode micropump. Preliminary experiments were performed on fluids with conductivity at 0.224 S/m. Particle trapping and micropumping were demonstrated at low voltages, reaching ∼100 µm/s for no more than 8 Vrms at 200 kHz. The fluid velocity was found to depend on the applied voltage as V4, and the maxima were observed to be ∼20 µm above the electrodes. - Author(s): N. Markhotina ; G.J. Liu ; D.K. Martin
- Source: IET Nanobiotechnology, Volume 1, Issue 3, p. 44 –51
- DOI: 10.1049/iet-nbt:20060019
- Type: Article
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44
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The normal function of retinal capillaries to distribute blood within the retina depends on appropriate contractility of retinal pericytes, which is thought to be modulated by agents that alter intracellular cyclic adenosine-3′-monophosphate (cAMP) levels. We examined the hypothesis that the vasoactive peptides Vasoactive Intestinal Peptide (VIP) and Pituitary Adenylate Cyclase Activating Peptide (PACAP) reduce pericyte contractility via a protein kinase A (PKA)-mediated intracellular pathway that utilises cAMP. We utilised a single-call assay of contractility that is based on visualising the contractile force exerted by the pericytes on a silicone elastomer substrate and quantified, as a contractility index, from the number and length of wrinkles induced in the silicone elastomer by the pericytes. Pericytes were cultured from the retinas of freshly killed abattoir cattle, and identified in culture using immunohistochemical techniques. The pericytes contracted in response to norepinephrine (EC50=8 µM) and relaxed in response to both VIP (EC50=48 nM) and PACAP (EC50=3 nM). The relaxation induced by PACAP was inhibited by Rp-cAMPS (EC50=26 µM), which is an agent that inhibits cAMP binding at PKA. We confirmed the activation of PKA by PACAP in experiments where H89 also inhibited the PACAP-induced relaxation. U71322, which inhibits phospholipase C-linked events, was also able to inhibit the PACAP-induced pericyte relaxation. Our results support the hypothesis that PACAP leads to the relaxation of pericytes via a PKA-mediated intracellular pathway and a phospholipase C-mediated pathway, which probably relies on hyperpolarisation because of activation of Ca2+-dependent potassium channels. This single-cell assay has proved useful as the basis for the development of a diagnostic procedure for diabetic retinopathy, which is an eye disease caused by abnormal regulation of blood flow in the retinal capillaries.
FISH and chips: chromosomal analysis on microfluidic platforms
AC electrothermal manipulation of conductive fluids and particles for lab-chip applications
Contractility of retinal pericytes grown on silicone elastomer substrates is through a protein kinase A-mediated intracellular pathway in response to vasoactive peptides
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