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© Springer International Publishing AG 2018. Rapid diagnosis of infectious diseases is necessary for timely treatment and to control spread of diseases. Conventional laboratory approaches are often labor-intensive and associated with time delays that are unacceptable in medical practice. Recent advances in micro-/nanotechnologies have facilitated the development of low-cost microfluidic devices with high sensitivity and throughput that can help reduce healthcare costs and pave the way toward personalized therapy. This chapter covers recent advances in point-of-care (POC) technologies with an emphasis on demonstrated and commercially available systems for diagnosis and treatment of malaria, sepsis, and human immunodeficiency virus (HIV) infection/acquired immune deficiency syndrome (AIDS). The current challenges to practical implementation of these technologies are discussed together with some future perspectives.

Cancer is a major cause of mortality worldwide, with a disease burden estimated to grow over the coming decades. Circulating tumor cells (CTCs) are rare cancer cells released from the primary or metastatic tumors and transported though the peripheral circulatory system to their specific secondary locations. The presence of CTCs in the a cancer patient’s blood has been used as a prognostic biomarker, with lower CTC count correlating with greater overall survival [1]. In spite of its clinical potential, the isolation and detection of CTCs has been a challenging task due to its rare presence amongst other blood cells (as low as 1-10 CTCs per billions of blood cells) and variability in terms of both morphological and biochemical markers. Recent developments of microfluidics technology have paved the way for better isolation and characterization of CTCs due to several advantages such as lower sample volume, higher sensitivity and throughput and lesser production cost [2, 3]. In this chapter, various CTC isolation devices are classified under two major categories: microfluidics and conventional macro-scale devices, as illustrated in Fig. 1. We will be discussing both label-free methods and antibody-dependent methods for CTC isolation, and will provide discussion and future perspectives on the advantages and drawbacks of both these techniques on potential clinical applications. Advancement in these technologies for CTCs and associated components, such as exosomes, led to an unraveling of tumor variation, ranging histology, molecular, proteomic and functional heterogeneity, which will be discussed in the subsequent sections.

Tumor heterogeneity is a major hindrance in cancer classification, diagnosis and treatment. Recent technological advances have begun to reveal the true extent of its heterogeneity. Single-cell analysis (SCA) is emerging as an important approach to detect variations in morphology, genetic or proteomic expression. In this review, we revisit the issue of inter- and intra-tumor heterogeneity, and list various modes of SCA techniques (cell-based, nucleic acid-based, protein-based, metabolite-based and lipid-based) presently used for cancer characterization. We further discuss the advantages of SCA over pooled cell analysis, as well as the limitations of conventional techniques. Emerging trends, such as high-throughput sequencing, are also mentioned as improved means for cancer profiling. Collectively, these applications have the potential for breakthroughs in cancer treatment.

Circulating tumor cells (CTCs) are rare cancer cells that are shed from primary or metastatic tumors into the peripheral blood circulation. Phenotypic and genetic characterization of these rare cells can provide important information to guide cancer staging and treatment, and thus further research into their characteristics and properties is an area of considerable interest. In this protocol, we describe detailed procedures for the production and use of a label-free spiral microfluidic device to allow size-based isolation of viable CTCs using hydrodynamic forces that are present in curvilinear microchannels. This spiral system enables us to achieve ≥ 85% recovery of spiked cells across multiple cancer cell lines and 99.99% depletion of white blood cells in whole blood. The described spiral microfluidic devices can be produced at an extremely low cost using standard microfabrication and soft lithography techniques (2-3 d), and they can be operated using two syringe pumps for lysed blood samples (7.5 ml in 12.5 min for a three-layered multiplexed chip). The fast processing time and the ability to collect CTCs from a large patient blood volume allows this technique to be used experimentally in a broad range of potential genomic and transcriptomic applications.