Centrifugation-Controlled Thermal Convection and Its Application to Rapid Microfluidic Polymerase Chain Reaction Devices.

Here, we report the developed cyclo olefin polymer (COP) microfluidic chip on a fabricated rotating heater stage that utilizes centrifugation-assisted thermal cycle in a ring-structured microchannel for polymerase chain reaction (PCR). The PCR solution could be driven by thermal convection and continuously exchanged high/low temperatures in a ring structured microchannel without the use of typical syringe pump. More importantly, the flow rate was controlled by the relative gravitational acceleration only. The platform enables amplification within 10 min at 5G and has a detection limit of 70.5 pg/channel DNA concentration (ß-actin, 295 bp). The current rotating system is capable of testing four different samples in parallel. The microfluidic chip can be preloaded with the PCR premix solution for on-site utility, and, with all of the features integrated to the system, the test can be conducted without the need for specialized laboratory and trained laboratory staff. In addition, this innovative chemical reaction technique has the potential to be utilized in other micromixing applications.

Prognostic Impact of Circulating Tumor Cell Detected Using a Novel Fluidic Cell Microarray Chip System in Patients with Breast Cancer.

Various types of circulating tumor cell (CTC) detection systems have recently been developed that show a high CTC detection rate. However, it is a big challenge to find a system that can provide better prognostic value than CellSearch in head-to-head comparison. We have developed a novel semi-automated CTC enumeration system (fluidic cell microarray chip system, FCMC) that captures CTC independently of tumor-specific markers or physical properties. Here, we compared the CTC detection sensitivity and the prognostic value of FCMC with CellSearch in breast cancer patients. FCMC was validated in preclinical studies using spike-in samples and in blood samples from 20 healthy donors and 22 breast cancer patients in this study. Using spike-in samples, a statistically higher detection rate (p=0.010) of MDA-MB-231 cells and an equivalent detection rate (p=0.497) of MCF-7 cells were obtained with FCMC in comparison with CellSearch. The number of CTC detected in samples from patients that was above a threshold value as determined from healthy donors was evaluated. The CTC number detected using FCMC was significantly higher than that using CellSearch (p=0.00037). CTC numbers obtained using either FCMC or CellSearch had prognostic value, as assessed by progression free survival. The hazard ratio between CTC+ and CTC- was 4.229 in CellSearch (95% CI, 1.31 to 13.66; p=0.01591); in contrast, it was 11.31 in FCMC (95% CI, 2.245 to 57.0; p=0.000244). CTC detected using FCMC, like the CTC detected using CellSearch, have the potential to be a strong prognostic factor for cancer patients.

Exploration of interactions between membrane proteins embedded in supported lipid bilayers and their antibodies by reflectometric interference spectroscopy-based sensing.

A microfluidic reflectometric interference spectroscopy (RIfS)-based sensor was fabricated to investigate the activity of multidrug resistance-associated protein 1 (MRP1), applied as a model membrane protein. Vesicles containing MRP1 were immobilized simply by injecting a vesicle solution (50 µg mL(-1)) onto a zirconium oxide (ZrO2) chip under constant flow conditions. Monitoring the shift of the minimum reflectance wavelength (Δλ) of the RIfS demonstrated that the vesicles were adsorbed onto the ZrO2 chip in a Langmuir-like fashion and suggested that the lipid bilayer structure was preserved on the ZrO2 chip. The theoretical maximum physical thickness of the layer was 4.97 nm, which was close to the values previously reported for supported lipid bilayers (4.2 to 5.2 nm). When a model protein, the anti-MRP1 antibody (1-50 µg mL(-1)), was injected onto the MRP1-immobilizing ZrO2 chip a concentration-dependent increase in Δλ was observed. In contrast, a ZrO2 chip on which the supported lipid bilayers did not contain MRP1 exhibited no response. Moreover, an anti-human IgG antibody generated no change in Δλ, confirming that anti-MRP1 antibodies were selectively bound to the MRP1 immobilized on the chip. These results show that the RIfS sensor can follow specific binding events of biologically active membrane proteins and represents a simple, label-free system capable of facilitating biomedical investigations.