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The field of inertial microfluidics has been significantly advanced in terms of application to fluid manipulation for biological analysis, materials synthesis, and chemical process control. Because of their superior benefits such as high-throughput, simplicity, and accurate manipulation, inertial microfluidics designs incorporating channel geometries generating Dean vortexes and helical vortexes have been studied extensively. However, existing technologies have not been studied by designing low-aspect-ratio microchannels to produce multi-vortexes. In this study, an inertial microfluidic device was developed, allowing the generation and regulation of the Dean vortex and helical vortex through the introduction of micro-obstacles in a semicircular microchannel with ultra-low aspect ratio. Multi-vortex formations in the vertical and horizontal planes of four dimension-confined curved channels were analyzed at different flow rates. Moreover, the regulation mechanisms of the multi-vortex were studied systematically by altering the micro-obstacle length and channel height. Through numerical simulation, the regulation of dimensional confinement in the microchannel is verified to induce the Dean vortex and helical vortex with different magnitudes and distributions. The results provide insights into the geometry-induced secondary flow mechanism, which can inspire simple and easily built planar 2D microchannel systems with low-aspect-ratio design with application in fluid manipulations for chemical engineering and bioengineering. [ABSTRACT FROM AUTHOR]

With the continuous development of cancer therapy, conventional animal models have exposed a series of shortcomings such as ethical issues, being time consuming and having an expensive cost. As an alternative method, microfluidic devices have shown advantages in drug screening, which can effectively shorten experimental time, reduce costs, improve efficiency, and achieve a large-scale, high-throughput and accurate analysis. However, most of these microfluidic technologies are established for narrow-range drug-concentration screening based on sensitive but limited flow rates. More simple, easy-to operate and wide-ranging concentration-gradient constructions for studying tumor cell–drug interactions in real-time have remained largely out of reach. Here, we proposed a simple and compact device that can quickly construct efficient and reliable drug-concentration gradients with a wide range of flow rates. The dynamic study of concentration-gradient formation based on successive spiral mixer regulations was investigated systematically and quantitatively. Accurate, stable, and controllable dual drug-concentration gradients were produced to evaluate simultaneously the efficacy of the anticancer drug against two tumor cell lines (human breast adenocarcinoma cells and human cervical carcinoma cells). Results showed that paclitaxel had dose-dependent effects on the two tumor cell lines under the same conditions, respectively. We expect this device to contribute to the development of microfluidic chips as a portable and economical product in terms of the potential of concentration gradient-related biochemical research. [ABSTRACT FROM AUTHOR]

Research and development of innovative targeted therapies is a great challenge in the fight against cancer. Although many treatment methods are currently available, there is no simple and effective system for promptly conducting anti-cancer drug screening and dose-response evaluation of the cancer patients to the drug. Herein, we developed an easy and compact flow rate independent microfluidic chip that can rapidly construct three concentration gradients of multiple solutes based on Dean flow under a wide range of flow rates. Chemical gradient dynamics were investigated systematically and quantitatively. Three stable, accurate, and controllable drug gradients were generated to evaluate treatments of two tumor cell lines (MCF-7 and HepG2). Results showed the dose- and time-dependent antitumor effects of the drugs, indicating the suitability of the proposed system to evaluate the individual actions and interactions of the anti-cancer drugs (doxorubicin and cisplatin) on one tumor cell line under the same conditions. In addition, cell viability in the microfluidic chip under gradient conditions showed a linear relationship to the viability of the traditional culture experiment. In summary, our microfluidic device can be used to develop insensitive techniques to operational conditions for simultaneously establishing multi-drug concentration gradients, which has the potential to promote the development of specific drug screening tools for targeting multiple vulnerabilities of tumor cells and evaluating the most effective personalized treatment technique. Image 1 • A novel cell analysis micro-chip was developed as supplying fresh medium continuously and sweeping cellular waste in time. • The micro-chip is capacity of establishing three stable, accurate and controllable drug-concentration gradients rapidly. • The generation of concentration gradient is steady and independent of specific flow rate when it is less than 200 μL min−1. • The system can simultaneously study the separate action and interaction of two drugs on one cell at three sets of gradients. [ABSTRACT FROM AUTHOR]