The “InstantCount” project develops printed microfluidic cell counting chambers for point-of-care blood tests, with the goal to provide diagnostics to resource-poor settings with no access to lab testing.
The concept of the test is based on the release of cell staining reagents from hydrogels to realize on-chip sample preparation. Based on this principle, we have demonstrated a simple and affordable CD4 count, a test that is used for HIV staging, and are currently developing printing techniques to fabricate these tests in an affordable and reproducible way. At the same time, new assays, such as a malaria test and a differential white blood cell count based on the same principle are developed and new materials for the release of reagents on microfluidic chips are tested.
Schematic representation of a microfluidic “InstantCount” chamber and the principle of its operation.
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InstantCount@MCBP
The “InstantCount” project develops rapid diagnostic blood tests for the monitoring and diagnosis of pandemic diseases (for example HIV or malaria) in low-income countries, with a focus on cell-counting applications. One example is the so-called CD4 count, i.e. the concentration of helper T-cells (= CD4-positive T-lymphocytes) in blood, which indicates the progression of an HIV infection and is therefore used to decide on the course of treatment with antiretroviral therapy. The current Gold Standard, flow cytometry, perfectly meets the requirements where many samples can be processed in well-controlled laboratories. However, as flow cytometers are expensive and require well-trained operators, especially rural areas in low-income countries do not have access to CD4 counting. These areas need an affordable test that can be carried out with a portable instrument by non-professionals with some hours of training, and which gives immediate and reliable results.
“InstantCount” cell counting chambers with on-chip sample preparation can fulfil these requirements. Blood is collected in a microfluidic counting chamber which contains dried cell staining reagents embedded in a gelatin film and fills by capillary flow. After incubation for 30 min, the staining of the cells is complete and they can be counted by fluorescence imaging and automatic image analysis. It has been shown that the CD4 counting chambers developed in this project can be used to determine a person’s CD4-positive T-lymphocyte level, using whole blood from a finger prick and that the resulting CD4 counts are comparable to the corresponding results determined by flow cytometry.
Schematic representation of a microfluidic “InstantCount” chamber and the principle of its operation.
The current activities comprise three main areas: new fabrication methods, new assays and new materials. Inkjet-printing processes are developed to fabricate the chambers in a reproducible way (Read More) that can be scaled to volume production. At the same time, the influence of the fabrication parameters and storage conditions on the performance of the CD4 count is monitored. Field tests in South Africa are going to be carried out to evaluate our approach. To include different tests that are often needed in the same setting on the same platform, a malaria test and a complete blood count based on similar principles are developed (Read More). To overcome some of the current limitations, and to include a larger variety of reagents, alternative materials for the delayed release of reagents on chip are tested (Read More).
Funding: ERC Starting Grant 282276
Contact: Markus Beck, PhD
Email: m.beck@utwente.nl
Tel: +31 (0)53-4894001
Medical Cell Biophysics
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