Exosomes, nanovesicles secreted by most types of cells, exist in virtually all bodily fluids. Their rich nucleic acid and protein content make them potentially valuable biomarkers for noninvasive molecular diagnostics. They also show promise, after further development, to serve as a drug delivery system. Unfortunately, existing exosome separation technologies, such as ultracentrifugation and methods incorporating magnetic beads, are time-consuming, laborious and separate only exosomes of low purity. Thus, a more effective separation method is highly desirable. Microfluidic platforms are ideal tools for exosome separation, since they enable fast, cost-efficient, portable and precise processing of nanoparticles and small volumes of liquid samples. Recently, several microfluidic-based exosome separation technologies have been studied. In this article, the advantages of the most recent technologies, as well as their limitations, challenges and potential uses in novel microfluidic exosome separation and collection applications is reviewed. This review outlines the uses of new powerful microfluidic exosome detection tools for biologists and clinicians, as well as exosome separation tools for microfluidic engineers. Current challenges of exosome separation methodologies are also described, in order to highlight areas for future research and development.

Background Drying efficiency and quality maintenance are the major concerns of both manufactures and consumers. Heat pump drying (HPD) is suitable for heat sensitive foodstuffs due to its ability to independently control the drying operation parameters. However, lower drying rate and energy efficiency in the later period of HPD are the bottlenecks that restrain its application. A novel approach using hydrocolloids as pretreatment coatings prior to drying was designed to solve these problems. The effects of sodium alginate (SA) coating, drying temperatures and air velocities on the drying characteristics and quality attributes of scallop adductors were evaluated. Results Drying took place in the falling rate period. Drying time decreased with increasing temperature, air velocity and SA coating. The Two Term model and the Wang and Singh model gained the best fit for thin‐layer drying of scallop adductors and SA film, respectively. Effective moisture diffusivity increased with temperature, velocity and SA coating and were in the range 7.352–14.620 × 10−11, 9.890–17.100 × 10−11 and 2.348–4.604 × 10−10 m2 s−1 for uncoated scallop adductors, SA coated scallop adductors and SA films, respectively. The activation energies for SA films, coated and uncoated scallop adductors were 17.07, 20.78 and 26.17 kJ mol−1, respectively. Dried scallop adductors with SA coating pretreatment exhibited a significant lower value of shrinkage rate and hardness, and higher value of toughness than uncoated ones at 30 °C and 2.0 m s−1 (P < 0.05). Conclusion Hydrocolloid coating is a promising pretreatment in improving HPD efficiency and enhancing quality attributes of dried scallop adductors. © 2019 Society of Chemical Industry

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