Force-Controlled Fluidic Injection into Single Cell Nuclei
Orane Guillaume-Gentil, Eva Potthoff, Dario Ossola, Pablo Dörig, Tomaso Zambelli, Julia A. Vorholt
Surpassing the physical barriers of the cytoplasmic and nuclear membranes to deliver biomolecules directly into cell nuclei offers opportunities to investigate dynamic processes in living cells. The potential of atomic force microscopy coupled to microfluidics (FluidFM) for volume-controlled intranuclear delivery is demonstrated, whereby minimally invasive microchanneled probes are remotely driven with high spatiotemporal resolution.
Volume 9, Issue 11, pages 1904–1907, June 10, 2013
Cusps, spouts and microfiber synthesis with microfluidics
Aurélien Duboin, Roxanne Middleton, Florent Malloggi, Fabrice Monti, Patrick Tabeling
We produced jets of two immiscible liquids in a standard microfluidic flow focusing geometry, using semi-dilute aqueous polymer solutions as the external phase and immiscible liquids, oil or photocurable polymers as the internal one. We map out the different flow regimes on a “phase diagram”. Two new flow regimes – oscillatory jet and spout – are observed, as a result of the non-Newtonian behavior of the external phase. In the spout regime, cusp-shaped interfaces form at the junction, emitting extremely small round jets (spouts), with diameters ranging between 1.2 and 7 μm, i.e. an order of magnitude smaller than the microchannel cross-sectional dimensions. These spouts are found to be stable over remarkably long distances. We analyze the properties of the cusps and the spouts in some detail. The system can be utilized to synthesize fibers of micrometric sizes: the fibers we obtained, under different flow conditions, have diameters ranging between 1.8 and 14 μm and lengths ranging between 0.5 mm and 2 centimeters.
Soft Matter, 2013,9, 3041-3049
Cellular building unit integrated with microstrand-shaped bacterial cellulose
Kayoko Hirayama, Teru Okitsu, Hiroki Teramae, Daisuke Kiriya, Hiroaki Onoe, Shoji Takeuchi
In bottom-up tissue engineering, a method to integrate a pathway of nutrition and oxygen into the resulting macroscopic tissue has been highly desired, but yet to be established. This paper presents a cellular building unit made from microstrand-shaped bacterial cellulose (BC microstrand) covered with mammalian cells. The BC microstrands are fabricated by encapsulating Acetobacter xylinum with a calcium alginate hydrogel microtube using a double co-axial microfluidic device. The mechanical strength and porous property of the BC microstrands can be regulated by changing the initial density of the bacteria. By folding or reeling the building unit, we demonstrated the multiple shapes of millimeter-scale cellular constructs such as coiled and ball-of-yarn-shaped structures. Histological analysis of the cellular constructs indicated that the BC microstrand served as a pathway of nutrition and oxygen to feed the cells in the central region. These findings suggest that our approach facilitates creating functional macroscopic tissue used in various fields such as drug screening, wound healing, and plastic surgery.
Volume 34, Issue 10, March 2013, Pages 2421–2427
Integrating solid-state sensor and microfluidic devices for glucose, urea and creatinine detection based on enzyme-carrying alginate microbeads
Yen-Heng Lin, Shih-Hao Wang, Min-Hsien Wu, Tung-Ming Pan, Chao-Sung Lai, Ji-Dung Luo, Chiuan-Chian Chiou
A solid-state sensor embedded microfluidic chip is demonstrated for the detection of glucose, urea and creatinine in human serum. In the presented device, magnetic powder-containing enzyme-carrying alginate microbeads are immobilized on the surface of an electrolyte-insulator-semiconductor (EIS) sensor by means of a step-like obstacle in the microchannel and an external magnetic force. The sample is injected into the microchannel and reacts with the enzyme contained within the alginate beads; prompting the release of hydrogen ions. The sample concentration is then evaluated by measuring the resulting change in the voltage signal of the EIS sensor. The reaction time and alginate bead size are optimized experimentally using a standard glucose solution. The experimental results show that the device has a detection range of 2–8 mM, 1–16 mM and 10−2–10 mM for glucose, urea and creatinine, respectively. Furthermore, it is shown that the device is capable of sequentially measuring all three indicators in a human serum sample. Finally, it is shown that the measured values of the glucose, urea and creatinine concentrations obtained using the device deviate from those obtained using a commercial kit by just 5.17%, 6.22% and 13.53%, respectively. This method can be extended to sequentially measure multiple blood indicators in the sample chip by replacing different types of enzyme in alginate bead and can address the enzyme preservation issue in the microfluidic device. Overall, the results presented in this study indicate that the microfluidic chip has significant potential for blood monitoring in point-of-care applications.
Biosensors and Bioelectronics
Volume 43, 15 May 2013, Pages 328–335
Droplet-based microfluidic system to form and separate multicellular spheroids using magnetic nanoparticles
Sungjun Yoon, Jeong Ah Kim, Seung Hwan Lee, Minsoo Kimb and Tai Hyun Park
The importance of creating a three-dimensional (3-D) multicellular spheroid has recently been gaining attention due to the limitations of monolayer cell culture to precisely mimic in vivo structure and cellular interactions. Due to this emerging interest, researchers have utilized new tools, such as microfluidic devices, that allow high-throughput and precise size control to produce multicellular spheroids. We have developed a droplet-based microfluidic system that can encapsulate both cells and magnetic nanoparticles within alginate beads to mimic the function of a multicellular tumor spheroid. Cells were entrapped within the alginate beads along with magnetic nanoparticles, and the beads of a relatively uniform size (diameters of 85% of the beads were 170–190 μm) were formed in the oil phase. These beads were passed through parallel streamlines of oil and culture medium, where the beads were magnetically transferred into the medium phase from the oil phase using an external magnetic force. This microfluidic chip eliminates additional steps for collecting the spheroids from the oil phase and transferring them to culture medium. Ultimately, the overall spheroid formation process can be achieved on a single microchip.
Lab Chip, 2013,13, 1522-1528
Optically clear alginate hydrogels for spatially controlled cell entrapment and culture at microfluidic electrode surfaces
Jordan F. Betz, Yi Cheng, Chen-Yu Tsao, Amin Zargar, Hsuan-Chen Wu, Xiaolong Luo, Gregory F. Payne, William E. Bentley and Gary W. Rubloff
We describe an innovation in the immobilization, culture, and imaging of cells in calcium alginate within microfluidic devices. This technique allows unprecedented optical access to the entirety of the calcium alginate hydrogel, enabling observation of growth and behavior in a chemical and mechanical environment favored by many kinds of cells.
Lab Chip, 2013,13, 1854-1858
Metre-long cell-laden microfibres exhibit tissue morphologies and functions
Hiroaki Onoe, Teru Okitsu, Akane Itou, Midori Kato-Negishi, Riho Gojo, Daisuke Kiriya, Koji Sato, Shigenori Miura, Shintaroh Iwanaga, Kaori Kuribayashi-Shigetomi, Yukiko T. Matsunaga, Yuto Shimoyama and Shoji Takeuchi
Artificial reconstruction of fibre-shaped cellular constructs could greatly contribute to tissue assembly in vitro. Here we show that, by using a microfluidic device with double-coaxial laminar flow, metre-long core–shell hydrogel microfibres encapsulating ECM proteins and differentiated cells or somatic stem cells can be fabricated, and that the microfibres reconstitute intrinsic morphologies and functions of living tissues. We also show that these functional fibres can be assembled, by weaving and reeling, into macroscopic cellular structures with various spatial patterns. Moreover, fibres encapsulating primary pancreatic islet cells and transplanted through a microcatheter into the subrenal capsular space of diabetic mice normalized blood glucose concentrations for about two weeks. These microfibres may find use as templates for the reconstruction of fibre-shaped functional tissues that mimic muscle fibres, blood vessels or nerve networks in vivo.
Nature Materials 12, 584–590 (2013)
Superhydrophobic Paper in the Development of Disposable Labware and Lab-on-Paper Devices
Maria Peixoto Sousa and João Filipe Mano
Traditionally in superhydrophobic surfaces history, the focus has frequently settled on the use of complex processing methodologies using nonbiodegradable and costly materials. In light of recent events on lab-on-paper emergence, there are now some efforts for the production of superhydrophobic paper but still with little development and confined to the fabrication of flat devices. This work gives a new look at the range of possible applications of bioinspired superhydrophobic paper-based substrates, obtained using a straightforward surface modification with poly(hydroxybutyrate). As an end-of-proof of the possibility to create lab-on-chip portable devices, the patterning of superhydrophobic paper with different wettable shapes is shown with low-cost approaches. Furthermore, we suggest the use of superhydrophobic paper as an extremely low-cost material to design essential nonplanar lab apparatus, including reservoirs for liquid storage and manipulation, funnels, tips for pipettes, or accordion-shaped substrates for liquid transport or mixing. Such devices take the advantage of the self-cleaning and extremely water resistance properties of the surfaces as well as the actions that may be done with paper such as cut, glue, write, fold, warp, or burn. The obtained substrates showed lower propensity to adsorb proteins than the original paper, kept superhydrophobic character upon ethylene oxide sterilization and are disposable, suggesting that the developing devices could be especially adequate for use in contact with biological and hazardous materials.
ACS Appl. Mater. Interfaces, 2013, 5 (9), pp 3731–3737