Purpose: Quantification of the heterogeneity of tumor cell populations is of interest for many diagnostic and therapeutic applications, including determining the cancerous stage of tumors. We attempted to differentiate human breast cancer cell lines from different pathologic stages and compare that with a normal human breast tissue cell line by characterizing the impedance properties of each cell line. Experimental Design: A microelectrical impedance spectroscopy system has been developed that can trap a single cell into an analysis cavity and measure the electrical impedance of the captured cell over a frequency range from 100 Hz to 3.0 MHz. Normal human breast tissue cell line MCF-10A, early-stage breast cancer cell line MCF-7, invasive human breast cancer cell line MDA-MB-231, and metastasized human breast cancer cell line MDA-MB-435 were used. Results: The whole-cell impedance signatures show a clear difference between each cell line in both magnitude and phase of the electrical impedance. The membrane capacitance calculated from the impedance data was 1.94 ± 0.14, 1.86 ± 0.11, 1.63 ± 0.17, and 1.57 ± 0.12 μF/cm² at 100 kHz for MCF-10A, MCF-7, MDA-MB-231, and MDA-MB-435, respectively. The calculated resistance for each cancer cell line at 100 kHz was 24.8 ± 1.05, 24.8 ± 0.93, 24.9 ± 1.12, and 26.2 ± 1.07 MOhm, respectively. The decrease in capacitances of the cancer cell lines compared with that of the normal cell line MCF-10A was 4.1%, 16.0%, and 19.1%, respectively, at 100 kHz. Conclusions: These findings suggest that microelectrical impedance spectroscopy might find application as a method for quantifying progression of cancer cells without the need for tagging or modifying the sampled cells.

We describe the development of a fully automatic and programmable microfluidic cell culture array that integrates on-chip generation of drug concentrations and pair-wise combinations with parallel culture of cells for drug candidate screening applications. The device has 64 individually addressable cell culture chambers in which cells can be cultured and exposed either sequentially or simultaneously to 64 pair-wise concentration combinations of two drugs. For sequential exposure, a simple microfluidic diffusive mixer is used to generate different concentrations of drugs from two inputs. For generation of 64 pair-wise combinations from two drug inputs, a novel time dependent variable concentration scheme is used in conjunction with the simple diffusive mixer to generate the desired combinations without the need for complex multi-layer structures or continuous medium perfusion. The generation of drug combinations and exposure to specific cell culture chambers are controlled using a LabVIEW interface capable of automatically running a multi-day drug screening experiment. Our cell array does not require continuous perfusion for keeping cells exposed to concentration gradients, minimizing the amount of drug used per experiment, and cells cultured in the chamber are not exposed to significant shear stress continuously. The utility of this platform is demonstrated for inducing loss of viability of PC3 prostate cancer cells using combinations of either doxorubicin or mitoxantrone with TRAIL (TNF-alpha Related Apoptosis Inducing Ligand) either in a sequential or simultaneous format. Our results demonstrate that the device can capture the synergy between different sensitizer drugs and TRAIL and demonstrate the potential of the microfluidic cell array for screening and optimizing combinatorial drug treatments for cancer therapy.

Bioprinting hydrogel microparticles requires consideration of size, stiffness, and nozzle geometry due to jamming effects.

Microbial fuel cells (MFCs) are remarkable “green energy” devices that exploit microbes to generate electricity from organic compounds. MFC devices currently being used and studied do not generate sufficient power to support widespread and cost-effective applications. Hence, research has focused on strategies to enhance the power output of the MFC devices, including exploring more electrochemically active microbes to expand the few already known electricigen families. However, most of the MFC devices are not compatible with high throughput screening for finding microbes with higher electricity generation capabilities. Here, we describe the development of a microfabricated MFC array, a compact and user-friendly platform for the identification and characterization of electrochemically active microbes. The MFC array consists of 24 integrated anode and cathode chambers, which function as 24 independent miniature MFCs and support direct and parallel comparisons of microbial electrochemical activities. The electricity generation profiles of spatially distinct MFC chambers on the array loaded with Shewanella oneidensis MR-1 differed by less than 8%. A screen of environmental microbes using the array identified an isolate that was related to Shewanella putrefaciens IR-1 and Shewanella sp. MR-7, and displayed 2.3-fold higher power output than the S. oneidensis MR-1 reference strain. Therefore, the utility of the MFC array was demonstrated.

The blood–brain barrier (BBB) poses a unique challenge to the development of therapeutics against neurological disorders due to its impermeabi-lity to most of the chemical compounds. Most in vitro BBB models have limitations in mimicking in vivo conditions and functions. Here, we show a co-culture microfluidic BBB-on-a-chip that provides interactions between neurovascular endothelial cells and neuronal cells across a porous polycarbonate membrane, which better mimics the in vivo conditions, as well as allows in vivo level shear stress to be applied. Methods: A 4 × 4 intersecting microchannel array forms 16 BBB sites on a chip, with a multielectrode array integrated to measure the transendothelial electrical resistance (TEER) from all 16 different sites, which allows label-free real-time analysis of the barrier function. Primary mouse endothelial cells and primary astrocytes were co-cultured in the chip while applying in vivo level shear stress. The chip allows the barrier function to be analyzed through TEER measurement, dextran permeability, as well as immunostaining. Results: Co-culture between astrocytes and endothelial cells, as well as in vivo level shear stress applied, led to the formation of tighter junctions and significantly lower barrier permeability. Moreover, drug testing with histamine showed increased permeability when using only endothelial cells compared to almost no change when using co-culture. Conclusion: Results show that the developed BBB chip more closely mimics the in vivo BBB environment. Significance: The developed multisite BBB chip is expected to be used for screening drug by more accurately predicting their permeability through BBB as well as their toxicity.