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BACKGROUND: We present a handheld integrated device based on a novel magnetic-optical technology for the sensitive detection of cardiactroponin I, a biomarker for the positive diagnosis of myocardial infarct, in a finger-prick blood sample. The test can be performed with a turn-around time of 5 minutes and can detect concentrations in the picomolar range in a sample volume of less than 25 L. METHOD: The test was completed in a compact, injection molded plasticdisposable with a 0.5 L assay chamber containing integrateddry magnetic nanoparticles and reagents. We have developed a 1-stepassay in which all reaction processes were precisely controlled bythe 3 electromagnetic coils positioned above and below the disposable. In the on-sensor assay, troponin molecules were sandwiched between capture antibodies attached to the detection surface and 500 nm superparamagnetic particles functionalized with tracer anti-troponinantibodies. Nanoparticles bound to the sensor surface were sensitively detected using the optical technique of frustrated total internalreflection (f-TIR). RESULT: A calibration function measured in 100%human plasma using our integrated test demonstrates a limit of detection (mean of blank plus 3 SD) of 0.03 ng/mL (1 pM) cTnI for a turn-around time of approximately 5 minutes. A linear regression analysis of the region 0.03-6.5 ng/mL yields a slope of 37 ± 4, intercept of 0.22±0.01 and linear correlation coefficient of R2=0.98. The measuring range could be extended substantially, to 100 ng/mL, by simultaneously imaging a second spot with lower capture antibody concentration. CONCLUSION: The combination of magnetic particles and their actuation with electromagnets permits the sensitive detection of cTnIto be performed rapidly. Because of the speed, ease-of-use and highanalytical sensitivity of the test, it is well suited for demandingpoint-of-care medical diagnostic applications.

Counting the different subpopulations of cells in a fingerprick of human blood is important for a number of clinical Point of Care applications. It is a challenge to demonstrate the integration of sample preparation and detection techniques in a single platform. In this article we review the applications for PoC haematology and the current solutions that are available. We demonstrate a generic microfluidic platform that combines sample processing and characterisation and enumeration in a single, integrated system. Results on microfluidic 3-part differential (granulocyte, lymphocyte, monocytes) together with erythrocyte and thrombocyte (platelet) counts on human blood are shown and corroborated with results from hospital clinical laboratory analysis. Conclusions: Identifying and counting the different subpopulations of human bloodcells is both clinically useful and technologically challenging. It provides a useful target application for the creation of a generic microfluidic platform technology in a single, hybrid cartidge. The prinicpal demand is to combine sample sample preparation with impedance cytometery to cover the large dynamic range in cell number, size and morphology. In particular, the ability to count both the relatively abundant, but small platelets at the same time as counting the relatively rare, but large monocytes, is a challenge. The technologies require good control of chemistry, accurate timming and control of flow, and precise control of concentrations, all of which are delivered through a well designed microfluidic sample preparation. The system described in this paper perform cell analysis and enumeration copuled with sample preprocessing and dilution. Using clinical blood, it has demonstrated good concordance with large scale hospital analysers. Beyond blood cell counting, the microfluidic platform technology will be useful in a range of applications in the future, including subtyping of blood cells, counting rare cells, cell assays and other matrices.