title: Rapid, low-cost and instrument-free CD4+ cell counting for HIV diagnostics in resource-poor settings.
abstract: We present a novel, user-friendly and widely autonomous point-of-care diagnostic to enable HIV monitoring in resource-poor regions where the current pandemic is most prevalent. To specifically isolate magnetically tagged CD4+ cells directly from patient blood, the low-cost and disposable microfluidic chip operates by dual-force CD4+ cell magnetophoresis; whereby the interplay of flow and magnetic fields governs the trajectory of target cells depending on whether the cell binds to a magnetic microbead. Instrument-free pumping is implemented by a finger-actuated elastic membrane; tagged beads are laterally deflected by a small and re-useable permanent magnet. The single-depth and monolithic microfluidic structure can easily be fabricated in a single casting step. After their magnetophoretic isolation from whole blood, estimation of CD4+ cell concentrations is then measured by bright-field inspection of the capture chamber. In addition, an optional fluorescence measurement can be used for confirmation of the bright-field result if required. On-chip CD4+ estimation produces a linear response over the full range of medically relevant CD4+ cell concentrations. Our technology combines high-efficiency capture (93.0 ± 3.3%) and cell enumeration.
authors.affiliation: Biomedical Diagnostics Institute, National Centre for Sensor Research, School of Physical Sciences, Dublin City University, Ireland. jens.ducree@dcu.ie macdara.glynn@dcu.ie.
authors.forename: Macdara T
authors.initials: MT
authors.lastname: Glynn
authors.forename: David J
authors.initials: DJ
authors.lastname: Kinahan
authors.forename: Jens
authors.initials: J
authors.lastname: Ducrée
mesh_terms: D055910:Antibodies, Immobilized / Q000737:chemistry / Q000191:economics / Q000378:metabolism*; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000191:economics / Q000378:metabolism*; D015704:CD4 Antigens / Q000737:chemistry / Q000378:metabolism*; D018791:CD4 Lymphocyte Count / Q000191:economics / Q000295:instrumentation*; D002138:Calibration; D002469:Cell Separation; D017046:Cost Savings; D004867:Equipment Design; D005456:Fluorescent Dyes / Q000737:chemistry; D015658:HIV Infections / Q000097:blood / Q000175:diagnosis / Q000191:economics / Q000276:immunology*; D018922:HL-60 Cells; D006801:Humans; D007211:Indoles / Q000737:chemistry; D007494:Ireland; D060328:Magnetic Phenomena; D008422:Materials Testing; D046210:Microfluidic Analytical Techniques / Q000191:economics / Q000295:instrumentation*; D008863:Microspheres; D010316:Particle Size; D019095:Point-of-Care Systems / Q000191:economics; D066330:Printing, Three-Dimensional; D011933:Reagent Kits, Diagnostic / Q000191:economics; D013997:Time Factors
chemical_list: D055910:Antibodies, Immobilized; D000911:Antibodies, Monoclonal; D015704:CD4 Antigens; D005456:Fluorescent Dyes; D007211:Indoles; D011933:Reagent Kits, Diagnostic; C007293:DAPI