Microarray surface chemistry and design set the geometry of lipid membrane nanotubes easily formed and observed in a microfluidic chamber.

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A great breadth of questions remains in cellular biology. Some questions cannot be answered using traditional analytical techniques and so demand the development of new tools for research. In the near future, the development of highly integrated microfluidic analytical platforms will enable the acquisition of unknown biological data. These microfluidic systems must allow cell culture under controlled microenvironment and high throughput analysis. For this purpose, the integration of a variable number of newly developed micro- and nano-technologies, which enable control of topography and surface chemistry, soluble factors, mechanical forces and cell–cell contacts, as well as technology for monitoring cell phenotype and genotype with high spatial and temporal resolution will be necessary. These multifunctional devices must be accompanied by appropriate data analysis and management of the expected large datasets generated. The knowledge gained with these platforms has the potential to improve predictive models of the behavior of cells, impacting directly in better therapies for disease treatment. In this review, we give an overview of the microtechnology toolbox available for the design of high throughput microfluidic platforms for cell analysis. We discuss current microtechnologies for cell microenvironment control, different methodologies to create large arrays of cellular systems and finally techniques for monitoring cells in microfluidic devices.

Low cost easy to use cell viability tests are needed in the pharmaceutical, biomaterial and environmental industry to measure adverse cellular effects. Herein we present a new methodology to track cell death with high resolution. We achieved dynamic digital quantification of cell viability by simple optical imaging using "Single Cell Adhesion Dot Arrays" (SCADA). Fibronectin (FN) dot arrays were fabricated on cell culture multiwell plates. The dot array was designed to accomodate a single cell on each fibronectin dot. For cytotoxicity measurements, cell-filled SCADA substrates were exposed to K2CrO4, HgSO4 salts and dimethyl sulfoxide (DMSO). Adherent cells commonly detach from the surface when they die. Dynamic monitoring of the toxic effect of DMSO and K2CrO4 was done measuring cell detachment rate during more than 30 hours by quantifying the number of occupied dots in the SCADA array. HgSO4 inhibited cellular detachment from the surface, and cytotoxicity was monitored using Trypan Blue life/death assay directly on the surface.In all cases, the cytotoxicity effects were easily monitored with single cell resolution and the results were comparable to previous reports. Cytotoxicity SCADA tests require only a transparent substrate, with a patterned area of less than 1 mm 2 and a reduced number of cells. SCADA enabled dynamic measurements at the highest resolution due to the digital measuring of this methodology. Integrated into microfluidic platforms, SCADA will provide a practical tool that will extent to fundamental research and commercial applications.

In vitro cytotoxicity testing is essential in the pharmaceutical and environmental industry to study the effects of potential harmful compounds for human health. Classical assays present several disadvantages: they are commonly based on live-death labelling, are highly time consuming and/or require skilled personnel to be performed. The current trend is to reduce the number of required cells and the time during the analysis, while increasing the screening capability and the accuracy and sensitivity of the assays, aiming single cell resolution. Microfabrication and surface engineering are enabling novel approaches for cytotoxicity assessment, offering high sensitivity and the possibility of automation in order to minimize user intervention. This review aims to overview the different microtechnology approaches available in this field, focusing on the novel developments for high-throughput, dynamic and real time screening of cytotoxic compounds.

Non-invasive collection of target cells is crucial for research in biology and medicine. In this work, we combine a thermo-responsive material, poly(N-isopropylacrylamide), with an electroactive material, poly(3,4-ethylenedioxythiopene):poly(styrene sulfonate), to generate a smart and conductive copolymer for the label-free and non-invasive detection of the capture and release of cells on gold electrodes by electrochemical impedance spectroscopy. The copolymer is functionalized with fibronectin to capture tumor cells, and undergoes a conformational change in response to temperature, causing the release of cells. Simultaneously, the copolymer acts as a sensor, monitoring the capture and release of cancer cells by electrochemical impedance spectroscopy. This platform has the potential to play a role in top-notch label-free electrical monitoring of human cells in clinical settings.Non-invasive collection of flowing cells such as Circulating Tumor Cells (CTCs) (

This work presents a new architecture concept for microfluidic devices, which combines the conventional 3D printing fabrication process with the stable and precise integration of polymeric functional materials in small footprints within the microchannels in well-defined locations. The approach solves the assembly errors that normally occur during the integration of functional and/or sensing materials in hybrid microfluidic devices. The method was demonstrated by embedding four pH-sensitive ionogel microstructures along the main microfluidic channel of a complex 3D printed microfluidic device. The results showed that this microfluidic architecture, comprising the internal integration of sensing microstructures of diverse chemical compositions, highly enhanced the adhesion force between the microstructures and the 3D printed microfluidic device that contains them. In addition, the performance of this novel 3D printed pH sensor device was investigated using image analysis of the pH colour variations obtained from photos taken with a conventional camera. The device presented accurate and repetitive pH responses in the 2 to 12 pH range without showing any type of device deterioration or lack of performance over time.

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