Following the development of microfluidic systems, there has been a high tendency towards developing lab-on-a-chip devices for biochemical applications. A great deal of effort has been devoted to improve and advance these devices with the goal of performing complete sets of biochemical assays on the device and possibly developing portable platforms for point of care applications. Among the different microfluidic systems used for such a purpose, digital microfluidics (DMF) shows high flexibility and capability of performing multiplex and parallel biochemical operations, and hence, has been considered as a suitable candidate for lab-on-a-chip applications. In this review, we discuss the most recent advances in the DMF platforms, and evaluate the feasibility of developing multifunctional packages for performing complete sets of processes of biochemical assays, particularly for point-of-care applications. The progress in the development of DMF systems is reviewed from eight different aspects, including device fabrication, basic fluidic operations, automation, manipulation of biological samples, advanced operations, detection, biological applications, and finally, packaging and portability of the DMF devices. Success in developing the lab-on-a-chip DMF devices will be concluded based on the advances achieved in each of these aspects.

We have reviewed the microfluidic approaches for cell/particle isolation and sorting, and extensively explained the mechanism behind each method.

Temozolomide (TMZ) is a chemotherapy agent used to treat Grade IV astrocytoma, also known as glioblastoma (GBM). TMZ treatment causes DNA damage that results in tumor cell apoptosis and increases the survival rate of GBM patients. However, chemoresistance as a result of TMZ‐induced autophagy significantly reduces this anticancer effects over time. Statins are competitive inhibitors of HMG‐CoA reductase, the rate‐limiting enzyme of the mevalonate (MEV) cascade. Statins are best known for their cholesterol (CH)‐lowering effect. Long‐term consumption of statins, prior to and in parallel with other cancer therapeutic approaches, has been reported to increase the survival rate of patients with various forms of cancers. In this study, we investigated the potentiation of TMZ‐induced apoptosis by simvastatin (Simva) in human GBM cell lines and patient GBM cells, using cell monolayers and three‐dimensional cell culture systems. The incubation of cells with a combination of Simva and TMZ resulted in a significant increase in apoptotic cells compared to cells treated with TMZ alone. Incubation of cells with CH or MEV cascade intermediates failed to compensate the decrease in cell viability induced by the combined Simva and TMZ treatment. Simva treatment inhibited the autophagy flux induced by TMZ by blocking autophago‐lysosome formation. Our results suggest that Simva sensitizes GBM cells to TMZ‐induced cell death in a MEV cascade‐independent manner and identifies the inhibition of autophagosome‐lysosome fusion as a promising therapeutic strategy in the treatment of GBM.

Glioblastoma multiforme (GBM) is a rapidly progressive and deadly form of brain tumor with a median survival rate of ~15 months. GBMs are hard to treat and significantly affect the patient’s physical and cognitive abilities and quality of life. Temozolomide (TMZ)—an alkylating agent that causes DNA damage—is the only chemotherapy choice for the treatment of GBM. However, TMZ also induces autophagy and causes tumor cell resistance and thus fails to improve the survival rate among patients. Here, we studied the drug-induced programmed cell death and invasion inhibition capacity of TMZ and a mevalonate cascade inhibitor, simvastatin (Simva), in a three-dimensional (3D) microfluidic model of GBM. We elucidate the role of autophagy in apoptotic cell death by comparing apoptosis in autophagy knockdown cells (Atg7 KD) against their scrambled counterparts. Our results show that the cells were significantly less sensitive to drugs in the 3D model as compared to monolayer culture systems. An immunofluorescence analysis confirmed that apoptosis is the mechanism of cell death in TMZ- and Simva-treated glioma cells. However, the induction of apoptosis in the 3D model is significantly lower than in monolayer cultures. We have also shown that autophagy inhibition (Atg7 KD) did not change TMZ and Simva-induced apoptosis in the 3D microfluidic model. Overall, for the first time in this study we have established the simultaneous detection of drug induced apoptosis and autophagy in a 3D microfluidic model of GBM. Our study presents a potential ex vivo platform for developing novel therapeutic strategies tailored toward disrupting key molecular pathways involved in programmed cell death and tumor invasion in glioblastoma.