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Bioactivated PDMS microchannel evaluated as sensor for human CD4+ cells: The concept of a point-of-care method for HIV monitoring
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology.
Uppsala University, Disciplinary Domain of Science and Technology, Technology, Department of Engineering Sciences, Applied Materials Sciences.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Physical and Analytical Chemistry, Analytical Chemistry.
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2007 (English)In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 123, no 2, 847-855 p.Article in journal (Refereed) Published
Abstract [en]

Up to today, the number of CD4(+) lymphocytes remains the most important biological marker to determine the clinical stage of an HIV-infection. Analysis by flow cytometry, the standard method used today, is unsuitable in many developing countries, because of high costs involved and practical inconveniences. We here present the concept of an inexpensive PDMS-based point-of-care device for CD4(-)count. A simple fluorescence microscope for stained leucocytes counting is the only detection equipment needed. The biosensor surface consists of an initial heparin-based coating that adds hydrophilicity and thromboresistance to the PDMS material. The specific capturing chemistry is based on an avidin/biotin-antibody surface architecture. Pure capillary forces draw whole blood, as well as rinsing buffer, into the biosensor channel, minimizing the need of external equipment. Detection of the captured cells was performed by fluorescence imaging of HOECHST (stains cell nuclei) and CD3-FITC signals. It was shown that the non-specific adsorption of CD4(-) leucocytes was minimal to none. and the detection could therefore be done by only counting the easy identifiable HOECHST+ cells. Characterization of the biosensor coating process was additionally performed with the quartz crystal microbalance-dissipation technique.

Place, publisher, year, edition, pages
2007. Vol. 123, no 2, 847-855 p.
Keyword [en]
PDMS, poly(dimethylsiloxane), HIV, CD4-count, point-of-care
National Category
Chemical Sciences Engineering and Technology Medical and Health Sciences
URN: urn:nbn:se:uu:diva-95126DOI: 10.1016/j.snb.2006.10.034ISI: 000247060100029OAI: oai:DiVA.org:uu-95126DiVA: diva2:169217
Available from: 2006-11-17 Created: 2006-11-17 Last updated: 2016-04-11Bibliographically approved
In thesis
1. Microfluidics in Surface Modified PDMS: Towards Miniaturized Diagnostic Tools
Open this publication in new window or tab >>Microfluidics in Surface Modified PDMS: Towards Miniaturized Diagnostic Tools
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

There is a strong trend in fabricating miniaturized total analytical systems, µTAS, for various biochemical and cell biology applications. These miniaturized systems could e.g. gain better separation performances, be faster, consume less expensive reagents and be used for studies that are difficult to access in the macro world. Disposable µTAS eliminate the risk of carry-over and can be fabricated to a low cost.

This work focused on the development of µTAS modules with the intentional use for miniaturized diagnostics. Modules for blood separation, desalting, enrichment, separation and ESI-MS detection were successfully fabricated. Surface coatings were additionally developed and evaluated for applications in µTAS with complex biological samples. The first heparin coating could be easily immobilized in a one-step-process, whereas the second heparin coating was aimed to form a hydrophilic surface that was able to draw blood or plasma samples into a microfluidic system by capillary forces.

The last mentioned heparin surface was further utilized when developing a chip-based sensor for performing CD4-count in human blood, an important marker to determine the stage of an HIV-infection.

All devices in this work were fabricated in PDMS, an elastomeric polymer with the advantage of rapid and less expensive prototyping of the microfabricated master. It was shown that PDMS could be considered as the material of choice for future commercial µTAS. The devices were intentionally produced using a low grade of fabrication complexity. It was however demonstrated that even with low complexity, it is possible to integrate several functional chip modules into a single microfluidic device.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2006. 52 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 241
Materials science, µTAS, micro total analysis system, PDMS, poly(dimethylsiloxane), microfluidics, heparin, blood filtration, on-chip, ESI-MS, desalting, QCM-D, biocompatible, CD4, capillary flow, lab-on-chip, microfabrication, enrichment, point-of-care, hydrophilic, oxidation, Materialvetenskap
urn:nbn:se:uu:diva-7270 (URN)91-554-6716-4 (ISBN)
Public defence
2006-12-08, Polhemsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:30
Available from: 2006-11-17 Created: 2006-11-17Bibliographically approved

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Nikolajeff, FredrikBergquist, Jonas
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Applied Materials SciencesDepartment of Oncology, Radiology and Clinical ImmunologyAnalytical Chemistry
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Chemical SciencesEngineering and TechnologyMedical and Health Sciences

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