Rapid and specific detection of cell-derived microvesicles using a magnetoresistive biochip.

Microvesicles (MVs) are a promising source of diagnostic biomarkers which have gained a wide interest in the biomedical and biosensing field. They can be interpreted as a "fingerprint" of various diseases. Nonetheless, MVs implementation into clinical settings has been hampered by the lack of technologies to accurately characterize, detect and quantify them. Here, we report the specific sensing and quantification of MVs from endothelial cells using a portable magnetoresistive (MR) biochip platform, in less than one hour and within physiologically relevant concentrations (1 × 108 MVs per ml). MVs were isolated from both endothelial and epithelial cells undergoing apoptosis, and characterized by atomic force microscopy (AFM) and nanoparticle tracking analysis (NTA), which revealed similar MV sizes. Importantly, our results showed that the two distinct MV populations could be discriminated with the MR biochip platform, with over a 5-fold capture efficiency of endothelial MVs in comparison to the control (epithelial MVs). Also, unspecific binding of MVs to BSA was less than 1% of the specific signal. The detection strategy was based on a sandwich immunoassay, where MVs were labelled with magnetic nanoparticles (MNPs) functionalized with Annexin V and then captured by anti-CD31 antibodies previously immobilized on the surface of the sensor. Results suggest that this approach allows the detection of specific MVs from complex samples such as serum, and highlight the potential of this technology to become a suitable tool for MVs detection as a complementary method of diagnosis.

High sensitivity point-of-care device for direct virus diagnostics.

Influenza infections are associated with high morbidity and mortality, carry the risk of pandemics, and pose a considerable economic burden worldwide. To improve the management of the illness, it is essential with accurate and fast point-of-care diagnostic tools for use in the field or at the patient's bedside. Conventional diagnostic methods are time consuming, expensive and require specialized laboratory facilities. We present a highly sensitive, highly specific, and low cost platform to test for acute virus infections in less than 15 min, employing influenza A virus (H1N1) as an example of its usability. An all polymer microfluidic system with a functionalized conductive polymer (PEDOT-OH:TsO) microelectrode array was developed and exploited for label free and real time electrochemical detection of intact influenza A virus (H1N1) particles. DNA aptamers with affinity for influenza A virus (H1N1) were linked covalently to the conductive polymer microelectrodes in the microfluidic channel. Based on changes in the impedance when virions were captured by immobilized probes, we could detect clinically relevant concentrations of influenza A virus (H1N1) in saliva. This is a new, stable and very sensitive point-of-care platform for detection and diagnostics of intact virus particles.

Highly controlled electrofusion of individually selected cells in dielectrophoretic field cages.

The prospect of novel therapeutic approaches has renewed the current interest in the fusion of rare cells, like stem cells or primary immune cells. While conventional techniques are only capable of mass fusion, lab-on-a-chip systems often still lack an acceptable method for making the cells available after processing. Here, we present a microfluidic approach for electrofusion on the single-cell level that offers high control over the cells both before and after fusion. For cell pairing and fusion, we employed dielectrophoresis and AC voltage pulses, respectively. Each cell has been characterized and selected before they were paired, fused and released from the fluidic system for subsequent analysis and cultivation. The successful experimental evaluation of our system was further corroborated by numerical simulations. We obtained fusion efficiencies of more than 30% for individual pairs of mouse myeloma and B cell blasts and showed the proliferating ability of the hybrid cells 3 d after fusion. Since aggregates of more than two cells can be fused, the technique could also be developed further for generating giant cells for low-noise electrophysiology in the context of semi-automated pharmaceutical screening procedures.