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Ovarian cancer (OvCa) is the second most common type of gynecological cancer. More seriously, the prognosis for survival is relatively poor if an early OvCa diagnosis is not achieved. However, it is extremely challenging to diagnose very early stage OvCa, when treatments are the most effective, because of the lack of specific and sensitive biomarkers. Therefore, in order to achieve early detection of OvCa, screening and identifying biomarkers with high specificity and affinity are greatly needed. In this study, an integrated microfluidic system capable of performing cell-based systematic evolution of ligands by an exponential enrichment (Cell-SELEX) process was developed for automatic, high-throughput screening of multiple cell lines to competitively select aptamer-based biomarkers for OvCa. This on-chip Cell-SELEX process only required five rounds of aptamer selection, which is much faster than using a conventional SELEX process (22 rounds). Using this on-chip process, 13 aptamers specific to OvCa cells were successfully screened and three of them showed high affinity towards target cells with dissociation constants of 1.8 nM, 8.3 nM, and 1.3 nM. Analysis of stained fluorescence images and competitive testing against multiple cancer cell lines (cervical cancer, breast cancer, lung cancer, and liver cancer) were performed to verify the specificity of these selected aptamers. The results demonstrated that this developed system could perform the on-chip Cell-SELEX selection successfully and could be applied for personalized aptamer screening or targeted therapy monitoring in the near future.

Early stage detection of lymphoma cells is invaluable for providing reliable prognosis to patients. However, the purity of lymphoma cells in extracted samples from human patients' marrow is typically low. To address this issue, we report here our work on using optically-induced dielectrophoresis (ODEP) force to rapidly purify Raji cells' (a type of Burkitt's lymphoma cell) sample from red blood cells (RBCs) with a label-free process. This method utilizes dynamically moving virtual electrodes to induce negative ODEP force of varying magnitudes on the Raji cells and RBCs in an optically-induced electrokinetics (OEK) chip. Polarization models for the two types of cells that reflect their discriminate electrical properties were established. Then, the cells' differential velocities caused by a specific ODEP force field were obtained by a finite element simulation model, thereby established the theoretical basis that the two types of cells could be separated using an ODEP force field. To ensure that the ODEP force dominated the separation process, a comparison of the ODEP force with other significant electrokinetics forces was conducted using numerical results. Furthermore, the performance of the ODEP-based approach for separating Raji cells from RBCs was experimentally investigated. The results showed that these two types of cells, with different concentration ratios, could be separated rapidly using externally-applied electrical field at a driven frequency of 50 kHz at 20 Vpp. In addition, we have found that in order to facilitate ODEP-based cell separation, Raji cells' adhesion to the OEK chip's substrate should be minimized. This paper also presents our experimental results of finding the appropriate bovine serum albumin concentration in an isotonic solution to reduce cell adhesion, while maintaining suitable medium conductivity for electrokinetics-based cell separation. In short, we have demonstrated that OEK technology could be a promising tool for efficient and effective purification of Raji cells from RBCs.

Negative selection-based circulating tumor cell (CTC) isolation is believed valuable to harvest more native, and in particular all possible CTCs without biases relevant to the properties of surface antigens on the CTCs. Under such a cell isolation strategy, however, the CTC purity is normally compromised. To address this issue, this study reports the integration of optically-induced-dielectrophoretic (ODEP) force-based cell manipulation, and a laminar flow regime in a microfluidic platform for the isolation of untreated, and highly pure CTCs after conventional negative selection-based CTC isolation. In the design, six sections of moving light-bar screens were continuously and simultaneously exerted in two parallel laminar flows to concurrently separate the cancer cells from the leukocytes based on their size difference and electric properties. The separated cell populations were further partitioned, delivered, and collected through the two flows. With this approach, the cancer cells can be isolated in a continuous, effective, and efficient manner. In this study, the operating conditions of ODEP for the manipulation of prostate cancer (PC-3) and human oral cancer (OEC-M1) cells, and leukocytes with minor cell aggregation phenomenon were first characterized. Moreover, performances of the proposed method for the isolation of cancer cells were experimentally investigated. The results showed that the presented CTC isolation scheme was able to isolate PC-3 cells or OEC-M1 cells from a leukocyte background with high recovery rate (PC-3 cells: 76-83%, OEC-M1 cells: 61-68%), and high purity (PC-3 cells: 74-82%, OEC-M1 cells: 64-66%) (set flow rate: 0.1 μl min(-1) and sample volume: 1 μl). The latter is beyond what is currently possible in the conventional CTC isolations. Moreover, the viability of isolated cancer cells was evaluated to be as high as 94 ± 2%, and 95 ± 3% for the PC-3, and OEC-M1 cells, respectively. Furthermore, the isolated cancer cells were also shown to preserve their proliferative capability. As a whole, this study has presented an ODEP-based microfluidic platform that is capable of isolating CTCs in a continuous, label-free, cell-friendly, and particularly highly pure manner. All these traits are found particularly meaningful for exploiting the harvested CTCs for the subsequent cell-based, or biochemical assays.

Ovarian cancer is the second most common of the gynecological cancers in Taiwan. It is challenging to diagnose at an early stage when proper treatment is the most effective. It is well recognized that the detection of tumor cells (TCs) is critical for determining cancer growth stages and may provide important information for accurate diagnosis and even prognosis. In this study, a new microfluidic platform integrated with a moving-wall micro-incubator, a micro flow cytometer and a molecular diagnosis module performed automated identification of ovarian cancer cells. By efficiently mixing the cells and immunomagnetic beads coated with specific antibodies, the target TCs were successfully isolated from the clinical samples. Then counting of the target cells was achieved by a combination of the micro flow cytometer and an optical detection module and showed a counting accuracy as high as 92.5 %. Finally, cancer-associated genes were amplified and detected by the downstream molecular diagnosis module. The fluorescence intensity of specific genes (CD24 and HE4) associated with ovarian cancer was amplified by the molecular diagnosis module and the results were comparable to traditional slab-gel electrophoresis analysis, with a limit of detection around 10 TCs. This integrated microfluidic platform realized the concept of a "lab-on-a-chip" and had advantages which included automation, disposability, lower cost and rapid diagnosis and, therefore, may provide a promising approach for the fast and accurate detection of cancer cells.

Human mesenchymal stem cells can differentiate into multiple lineages for cell therapy and, therefore, have attracted considerable research interest recently. This study presents a new microfluidic device for bead and cell separation utilizing a combination of T-junction focusing and tilted louver-like structures. For the first time, a microfluidic device is used for continuous separation of amniotic stem cells from amniotic fluids. An experimental separation efficiency as high as 82.8% for amniotic fluid mesenchymal stem cells is achieved. Furthermore, a two-step separation process is performed to improve the separation efficiency to 97.1%. These results are based on characterization experiments that show that this microfluidic chip is capable of separating beads with diameters of 5, 10, 20, and 40 microm by adjusting the volume-flow-rate ratio between the flows in the main and side channels of the T-junction focusing structure. An optimal volume-flow-rate ratio of 0.5 can lead to high separation efficiencies of 87.8% and 85.7% for 5-microm and 10-microm beads, respectively, in a one-step separation process. The development of this microfluidic chip may be promising for future research into stem cells and for cell therapy.

The current study presents a new miniature microfluidic flow cytometer integrated with several functional micro-devices capable of viral sample purification and detection by utilizing a magnetic bead-based immunoassay. The magnetic beads were conjugated with specific antibodies, which can recognize and capture target viruses. Another dye-labeled anti-virus antibody was then used to mark the bead-bound virus for the subsequent optical detection. Several essential components were integrated onto a single chip including a sample incubation module, a micro flow cytometry module and an optical detection module. The sample incubation module consisting of pneumatic micropumps and a membrane-type, active micromixer was used for purifying and enriching the target virus-bound magnetic beads with the aid of a permanent magnet. The micro flow cytometry module and the optical detection module were used to perform the functions of virus counting and collection. Experimental results showed that virus samples with a concentration of 10(3)PFU/ml can be automatically detected successfully by the developed system. In addition, the entire diagnosis procedure including sample incubation and virus detection took only about 40min. Consequently, the proposed micro flow cytometry may provide a powerful platform for rapid diagnosis and future biological applications.

This paper reports a new microfluidic device capable of performing optically induced flow cytometry (OIFC). This enables it to continuously count and to sort microparticles based on optically induced dielectrophoretic (ODEP) forces. Gravity was used to drive the particles instead of using syringe pumps. The particles were then focused inside a sample channel by the ODEP forces and then passed through a detection region. A pair of optical fibers were embedded into fiber channels to count the number of particles and analyze the particle size in real time. Using 20.9 and 9.7 microm polystyrene microparticles, the average light intensity were about 63.67 and 8.80 units, with a coefficient-of-variation (CV) of 7.46 and 25.57%, respectively. This demonstrated that these two particle sizes could be successfully distinguished. After detecting the number and size of the microparticles, an optically induced dynamic switch (ODS) was used to sort microparticles to downstream fluidic outlets. The ODS used ODEP forces generated by different illumination intensities or optical line widths. The ODS was composed of two virtual electrodes which controlled particle movement in two dimensions. The ODS can successfully sort microparticles with different sizes continuously. The development of the OIFC device is a major advancement in the design of microparticle counting and sorting devices. Applications in future biomedical applications for cell counting and manipulation are envisioned.

This study reports a new biochip capable of cell separation and nucleus collection utilizing dielectrophoresis (DEP) forces in a microfluidic system comprising of micropumps and microvalves, operating in an automatic format. DEP forces operated at a low voltage (15 Vp-p) and at a specific frequency (16 MHz) can be used to separate cells in a continuous flow, which can be subsequently collected. In order to transport the cell samples continuously, a serpentine-shape (S-shape) pneumatic micropump device was constructed onto the chip device to drive the samples flow through the microchannel, which was activated by the pressurized air injection. The mixed cell samples were first injected into an inlet reservoir and driven through the DEP electrodes to separate specific samples. Finally, separated cell samples were collected individually in two outlet reservoirs controlled by microvalves. With the same operation principle, the nucleus of the specific cells can be collected after the cell lysis procedure. The pumping rate of the micropump was measured to be 39.8 microl/min at a pressure of 25 psi and a driving frequency of 28 Hz. For the cell separation process, the initial flow rate was 3 microl/min provided by the micropump. A throughput of 240 cells/min can be obtained by using the developed device. The DEP electrode array, microchannels, micropumps and microvalves are integrated on a microfluidic chip using micro-electro-mechanical-systems (MEMS) technology to perform several crucial procedures including cell transportation, separation and collection. The dimensions of the integrated chip device were measured to be 6x7 cm. By integrating an S-shape pump and pneumatic microvalves, different cells are automatically transported in the microchannel, separated by the DEP forces, and finally sorted to specific chambers. Experimental data show that viable and non-viable cells (human lung cancer cell, A549-luc-C8) can be successfully separated and collected using the developed microfluidic platform. The separation accuracy, depending on the DEP operating mode used, of the viable and non-viable cells are measured to be 84 and 81%, respectively. In addition, after cell lysis, the nucleus can be also collected using a similar scheme. The developed automatic microfluidic platform is useful for extracting nuclear proteins from living cells. The extracted nuclear proteins are ready for nuclear binding assays or the study of nuclear proteins.