Advances in tumor-endothelial cells co-culture and interaction on microfluidics

The metastasis in which the cancer cells degrade the extracellular matrix （ECM） and invade to the sur- rounding and far tissues of the body is the leading cause of mortality in cancer patients, With a lot of advancement in the field, yet the biological cause of metastasis are poorly understood, The microfluidic system provides advanced technology to reconstruct a variety of in vivo-like environment for studying the interactions between tumor ceils （TCs） and endothelial ceils （ECs）. This review gives a brief account of both two-dimensional models and three-dimensional microfluidic systems for the analysis of TCs-ECs co- culture as well as their applications to anti-cancer drug screening, Furthermore, the advanced methods for analyzing cell-to-cell interactions at single-cell level were also discussed,

A microfluidic photolithography for controlled encapsulation of single cells inside hydrogel microstructures

为单个房间的控制封装在 microchannels 内产生 hydrogel 微观结构的一条 microfluidic 途径被开发。方法基于允许的修改显微镜设计影印石版术 photopolymerization poly (乙烯乙二醇) diacrylate (PEG-DA ) 里面 microchannels。制服大小的 hydrogel 微观结构(在直径的 50 m ) 与坚定的位置一个一个地被产生没有失去生存能力，包含单个房间。兴趣的房间能被有选择地在形成的 hydrogel 微观结构内要包含的任何种可见标签识别。单个房间的大规模封装与 80% 的相对高的效率被完成，包含的房间的生存能力能被移开与 Trypan 蓝色识别的死了的房间保证。这个方法对模式简单、快、方便有为大量基于房间的应用程序的单个房间的 microchannels。为示范， carboxylesterase 的二细胞内部的酶试金被执行在包含的单个 HepG2 房间以内调查酶集中和运动信息的分发。

Microfluidic adhesion analysis of single glioma cells for evaluating the effect of drugs

Cancer metastasis is one of the most serious problems for tumor therapy,which is closely related to cell adhesion and deadhesion process.Better comprehension of cell adhesion ability will benefit drug research.Here,a biomimetic microfluidic enzyme digestion method was proposed to gently measure the influence of drugs on cell-matrix adhesion ability at the single cell level.The method can selectively digest the extracellular matrix(ECM)that linked to a single cell,and the trypsin concentration around the cell is relatively uniform and constant,thus the measured cell adhesion strength should be precise.Commercially available anti-cancer agents including 5-fluorouracil(5-FU),actinomycin D(Act D),temozolomide(TMZ)and allicin were evaluated,and the data showed only TMZ and allicin can inhibit cell adhesion significantly under our experiment conditions.The influence of TMZ became more and more obvious as the increase of duration and the effect became prominent only after 6 h adhesion process,which could provide a quick evaluation of whether the drugs are effective to cancer cell(compared with Calcein-AM/PI cell viability test).The adhesion strength of U87 cells decreased when the concentration of TMZ increased,and the effect of TMZ can be effectively inhibited by adding lactic acid to culture medium,which indicated acidic tumor microenvironment could promote drug resistance of tumor cells.Different from conventional evaluation methods which focus on the drugs’influence on cellular viability or metabolism,this work provides a new perspective to study the effect of drugs,which is helpful to enrich the drug evaluation system.

Chip-based SALDI-MS for rapid determination of intracellular ratios of glutathione to glutathione disulfide

Alterations in the ratio of glutathione(GSH) to glutathione disulfide(GSSG) reveal the cell living state and are associated with a variety of diseases. In this study, an Au NPs grafted nanoporous silicon chip was used for surface assisted laser desorption ionization-mass spectrometry(SALDI-MS) detection of GSH. Due to the bond interaction between thiol of GSH and Au NPs modified on the chip surfaces, GSH could be captured from the complex cellular lysate. Meanwhile, the composite nanostructures of Au NPs grafted porous silicon surface presented good desorption/ionization efficiency for GSH detection. The GSH levels in different tumor cells were successfully detected. Chip-based SALDI-MS was optimized for quantification of intracellular GSH/GSSG ratio changing under drug stimulation in liver tumor cells, GSSG was reduced to GSH by reductant of tris(2-carboxyethyl)phosphine(TCEP) and isotope-labeling GSH was as an internal standard. It was found that the increasing concentration of drug irinotecan and hypoxia culture condition caused the rapid consumption of GSH and a decrease of GSH/GSSG ratio in liver tumor cells. The developed SALDI-MS method provided a convenient way to accurately measure and rapidly monitor cellular GSH value and the ratios of GSH/GSSG.

Multi-channel microfluidic chip-mass spectrometry platform for cell analysis

In this review, we highlight the latest development of multi-channel microfluidic chip-mass spectrometry（chip-MS） in cell analysis and metabolite detection. Following a brief introduction about history and development of multi-channel microchip and MS combination, we will elaborate the key issues of constructing chip-MS platform interface. Then exciting progresses made in this field should be reviewed with well exemplified works, including chip-MS technology for cell introduction, pretreatment of cell secretions and cell metabolite analysis. We will also describe the development of integrated total analysis systems proposed by our group. We hope this brief review will inspire interested readers and provide knowledge about chip-MS platform in the bioanalysis field, particularly in cell analysis and metabolite identifying applications.

A chemo-mechanical switchable valve on microfluidic chip based on a thermally responsive block copolymer

Microfluidic devices have become a powerful tool for chemical and biologic applications.To control different functional parts on the microchip,valve plays a key role in the device.In conventional methods,physio-mechanical valves are usually used on microfluidic chip.Herein,we reported a chemo-mechanical switchable valve on microfluidic chip by using a thermally responsive block copolymer.The wettability changes of capillary with copolymer modification on inner surface were investigated to verify the function as a valve.Capillaries with modification of poly-(N-isopropylacrylamide-co-hexafluoroisopropyl acrylate)(P(NIPAAm-co-HFIPA))with a 20%HFIPA was demonstrated capable of control aqueous solution stop or go through.Then short capillaries with copolymer modification were integrated in microchannels as valves.With the temperature changing around lower critical solution temperature(LCST),the integrated chemo-mechanical switchable valve exhibited excellent“OPEN–CLOSE”behavior for microflow control.After optimization of the block copolymer sequences and molar ratio,a switching time as low as 20 s was achieved.The developed micro valve was demonstrated effective for flow control on microchip.

Inhibition of anaerobic probiotics on colorectal cancer cells using intestinal microfluidic systems

Intestinal flora play an important role in human's immune system. Many bacteria adhere to the wall of the testinal wall. These Intestinal flora help digestion, and also stop their disease-causing counterparts from invading. Most of the current researches focused on the interaction between cells and the construction of organs, but few researches studied on the role of microorganisms and cells. Here, we developed an in vitro living cell systems to simulate the structure, absorption, transport and pathophysiological characteristics of the human intestinal tract and the key microbial symbiosis. The co-culture of Clostridium butyricum(C.butyricum) and colon cancer cells showed a different immune effect. C. butyricum could inhibit the proliferation of HCT116 cells, cause cell cycle arrest and promote apoptosis. But it had no significant effect on Caco-2 cells. Thus, basic functional characteristics of the gut were successfully simulated in a controlled microfluidic system. This approach is suggested as a powerful method in the investigation on drug metabolism and intestinal diseases.