Microfluidic blood plasma separation for medical diagnostics: is it worth it?

Circulating biomarkers are on the verge of becoming powerful diagnostic tools for various human diseases. However, the complex sample composition makes it difficult to detect biomarkers directly from blood at the bench or at the point-of-care. Blood cells are often a source of variability of the biomarker signal. While the interference of hemoglobin is a long known source of variability, the release of nucleic acids and other cellular components from hemocytes is a new concern for measurement and detection of circulating extracellular markers. Research into miniaturised blood plasma separation has been thriving in the last 10 years (2006-2016). Most point-of-care systems need microscale blood plasma separation, but developed solutions differ in complexity and sample volume range. But could blood plasma separation be avoided completely? This focused review weights the advantages and limits of miniaturised blood plasma separation and highlights the most interesting advances in direct capture as well as smart blood plasma separation.

Exosome isolation: a microfluidic road-map.

Exosomes, first isolated 30 years ago, are nanoscale vesicles shed by most types of cells. The nucleic acid rich content of these nanoparticles, floating in virtually all bodily fluids, has great potential for non-invasive molecular diagnostics and may represent a novel therapeutic delivery system. However, current isolation techniques such as ultracentrifugation are not convenient and do not result in high purity isolation. This represents an interesting challenge for microfluidic technologies, from a cost-effective perspective as well as for enhanced purity capabilities, and point-of-care acquisition and diagnosis. In this frontier review, we present the current challenges, comment the first microfluidic advances in this new field and propose a roadmap for future developments. This review enables biologists and clinicians familiar with exosome enrichment to assess the performance of novel microfluidic devices and, equally, enables microfluidic engineers to educate themselves about this new class of promising biomarker-rich particles and the challenges arising from their clinical use.

Validation of a fully integrated platform and disposable microfluidic chips enabling parallel purification of genome segments for assembly.

Recent progress in the field of genetic engineering has opened up the door to novel synthetic biology applications. Microfluidic technology has been emphasized as a key technology to support the development of these applications. While several important synthetic biology protocols have been developed in microfluidic format, no study has yet demonstrated on-chip error control. In synthetic biology protocols, the purification phase is a critical error control process which enhances the reliability of the genome segment assembly by removing undesired oligos. In this context, we report the design and characterization of a fully integrated platform, demonstrating the purification of up to 4 genome segments in parallel, prior to their off-chip assembly. The key innovation of this platform is the decoupling control strategy which eliminates the need to integrate expensive components onto the microfluidic device, enabling lower cost, disposability and rapid operation. Unlike most microfluidic chips where fluid connector plugs are needed to connect external pumps, this approach is plug-less and the chips are simply connected to the control breadboard by clamping. Furthermore the passive chip is isolated from the active control layer thereby eliminating the risk of sample-to-sample contamination in the reusable parts. As a validation of this fully-integrated system, the parallel on-chip purification of genome segments was demonstrated with ratio of correct phenotypes after final assembly up to 20% superior to the bench controls, proving thereby the suitability of the platform for synthetic biology applications.

Current and emerging techniques of fetal cell separation from maternal blood.

Intense research has been carried out in recent years into methods that aim to harvest fetal genetic material from maternal blood as substitutes to amniocentesis and chorionic villus sampling. Just over 30 years have past since the first fetal cells were separated from maternal blood using flow cytometry highlighting the prospect of non-invasive prenatal diagnosis of fetal abnormalities. The aim of this review paper is to describe the most commonly used cell separation methods with emphasis on the isolation of fetal cells from maternal blood. The most significant breakthroughs and advances in fetal cell separation are reviewed and critically analyzed. Although much has been accomplished using well established techniques, a rapid and inexpensive method to separate fetal cells with great accuracy, sensitivity and efficiency to maximize cell yield is still required. In the past decade MEMS (Micro Electro Mechanical Systems) technologies have enabled the miniaturization of many biological and medical laboratory processes. Lab-on-chip systems have been developed and encompass many modules capable of processing different biological samples. Such chips contain various integrated components such as separation channels, micropumps, mixers, reaction and detection chambers. This article will also explore new emerging MEMS based separation strategies, which hope to overcome the current limitations in fetal cell separation.

Recent advances in microparticle continuous separation.

Recent advances in microparticle separation in continuous flow are presented. It is intended for scientists in the field of separation science in biology, chemistry and microsystems engineering. Recent techniques of micron-sized particle separation within microsystems are described with emphasis on five different categories: optical, magnetic, fluidic-only, electrical and minor separation methods. Examples from the growing literature are explained with insights on separation efficiency and microengineering challenges. Current applications of the techniques are discussed.