Université PSL



Laboratory :
Author :
Revue :
Year :
New non-covalent strategies for stable surface treatment of thermoplastic chips
Karla Perez-Toralla, Jérôme Champ, Mohamad Reza Mohamadi, Olivier Braun, Laurent Malaquin, Jean-Louis Viovy and Stéphanie Descroix
Lab. Chip - 13(22) 4409-18 - DOI: 10.1039/c3lc50888a - 2013
In order to be more extensively used outside of research laboratories, lab-on-chip technologies must be mass-produced using low-cost materials such as thermoplastics. Thermoplastics, however, are generally hydrophobic in their native state, which makes them unsuitable for direct use with biological samples in aqueous solution, and thus require surface coating. This coating should be robust, inexpensive and simple to implement, in order not to hinder the industrial advantage of thermoplastic chips. Cyclic Olefin Copolymer (COC) is a particularly appealing polymer, but it is also difficult to functionalize due to its chemical inertness. Here we introduce and compare the performance of two new approaches for COC coating. One relies on the use of a commercial triblock copolymer, Pluronic® F127. The second approach uses new copolymers synthesized by radical polymerization, and consisting of a dimethylacrylamide (DMA) backbone carrying aliphatic side chains (C22). Two DMA-C22 copolymers were synthesized with various C22/DMA ratios: DMA-S at 0.175% and DMA-M at 0.35%. Different physicochemical properties of the polymers such as critical micellar concentration (CMC), water contact angle, electroosmosis were investigated. Coated COC chips were then tested for their ability to reduce the adsorption of proteins, microparticles, and for protein electrophoresis. For each application we found an optimal treatment protocol to considerably improve the performance of the thermoplastic chip. These treatments use physisorption in situ which requires no photografting or chemical reaction and can be performed by a simple incubation either after chip production, or just prior to use.
FISH in chips: turning microfluidic fluorescence in situ hybridization into a quantitative and clinically reliable molecular diagnosis tool
Perez-Toralla Karla, Mottet Guillaume, Guneri Ezgi Tulukcuoglu, Champ Jérôme, Bidard François-Clément, Jean-Yves Pierga, Jerzy Klijanienko, Irena Draskovic, Laurent Malaquin, Jean-Louis Viovya and Stéphanie Descroix*
Lab. Chip - 15 (2015) 811-22 - DOI: 10.1039/c4lc01059k - 2013
Microfluidic systems bear promise to provide new powerful tools for the molecular characterization of cancer cells, in particular for the routine detection of multiple cancer biomarkers using a minute amount of the sample. However, taking miniaturized cell-based assays into the clinics requires the implementation and validation of complex biological protocols on chip, as well as the development of disposable microdevices produced at a low cost. Based on a recently developed microfluidic chip made of Cyclic Olefin Copolymer for cell immobilization with minimal dead volume and controlled shear stress, we developed a protocol performed entirely in the liquid phase, allowing the immobilization and fixation of cells and their quantitative characterization by fluorescence in situ hybridization. We demonstrated first in cell lines and then in two clinical case studies the potential of this method to perform quantitative copy number measurement and clinical scoring of the amplification of the ERBB2 gene, a decisive biomarker for the prescription of HER2+ related targeted therapies. This validation was performed in a blind protocol in two clinical case studies, in reference to the gold standard and clinically used method based on glass slides. We obtained a comparable reproducibility and a minor difference in apparent amplification, which can be corrected by internal calibration. The method thus reaches the standard of robustness needed for clinical use. The protocol can be fully automated, and its consumption of samples and DNA probes is reduced as compared to glass slide protocols by a factor of at least 10. The total duration of the assay is divided by two.
Supershear Rayleigh Waves at a Soft Interface
Anne Le Goff, Pablo Cobelli, and Guillaume Lagubeau
Phys. Rev. Lett. - Vol.110 236101 - DOI: http://dx.doi.org/10.1103/PhysRevLett.110.236101 - 2013
We report on the experimental observation of waves at a liquid foam surface propagating faster than the bulk shear waves. The existence of such waves has long been debated, but the recent observation of supershear events in a geophysical context has inspired us to search for their existence in a model viscoelastic system. An optimized fast profilometry technique allows us to observe on a liquid foam surface the waves triggered by the impact of a projectile. At high impact velocity, we show that the expected subshear Rayleigh waves are accompanied by faster surface waves that can be identified as supershear Rayleigh waves.
Electronic hybridization detection in microarray format and DNA genotyping
Antoine Blin, Ismaïl Cissé and Ulrich Bockelmann
Scientific Reports - 4(n°4194) - DOI: 10.1038/srep04194 - 2013
We describe an approach to substituting a fluorescence microarray with a surface made of an arrangement of electrolyte-gated field effect transistors. This was achieved using a dedicated blocking of non-specific interactions and comparing threshold voltage shifts of transistors exhibiting probe molecules of different base sequence. We apply the approach to detection of the 35delG mutation, which is related to non-syndromic deafness and is one of the most frequent mutations in humans. The process involves barcode sequences that are generated by Tas-PCR, a newly developed replication reaction using polymerase blocking. The barcodes are recognized by hybridization to surface attached probes and are directly detected by the semiconductor device.
Revealing the competition between peeled DNA, melting bubbles, and S-DNA during DNA overstretching using fluorescence microscopy
Graeme A. Kinga, Peter Grossa, Ulrich Bockelmannb, Mauro Modestic, Gijs J. L. Wuitea, and Erwin J. G. Petermana
Proc. Nat. Acad. Sci. USA - vol.110 (n°10) 3859–64 - DOI: 10.1073/pnas.1213676110 - 2013
Mechanical stress plays a key role in many genomic processes, such as DNA replication and transcription. The ability to predict the response of double-stranded (ds) DNA to tension is a cornerstone of understanding DNA mechanics. It is widely appreciated that torsionally relaxed dsDNA exhibits a structural transition at forces of ∼65 pN, known as overstretching, whereby the contour length of the molecule increases by ∼70%. Despite extensive investigation, the structural changes occurring in DNA during overstretching are still generating considerable debate. Three mechanisms have been proposed to account for the increase in DNA contour length during overstretching: strand unpeeling, localized base-pair breaking (yielding melting bubbles), and formation of S-DNA (strand unwinding, while base pairing is maintained). Here we show, using a combination of fluorescence microscopy and optical tweezers, that all three structures can exist, uniting the often contradictory dogmas of DNA overstretching. We visualize and distinguish strand unpeeling and melting-bubble formation using an appropriate combination of fluorescently labeled proteins, whereas remaining B-form DNA is accounted for by using specific fluorescent molecular markers. Regions of S-DNA are associated with domains where fluorescent probes do not bind. We demonstrate that the balance between the three structures of overstretched DNA is governed by both DNA topology and local DNA stability. These findings enhance our knowledge of DNA mechanics and stability, which are of fundamental importance to understanding how proteins modify the physical state of DNA.
Cyclic Olefin Copolymer Plasma millireactors
Schelcher G, Guyon C, Ognier S, Cavadias S, Martinez E, Taniga V, Malaquin L, Tabeling P and Tatoulian M
Lab. Chip - 14(16) 3037-42 - DOI: 10.1039/c4lc00423j - 2013
The novelty of this paper lies in the development of a multistep process for the manufacturing of plasma millireactors operating at atmospheric pressure. The fabrication process relies on the integration of metallic electrodes over a cyclic olefin copolymer chip by a combination of photopatterning and sputtering. The developed plasma millireactors were successfully tested by creating air discharges in the gas volume of the millichannel. A sputtered silica layer was deposited on the channel walls to provide a barrier between the plasma and the polymer in order to prevent the alteration of polymer surfaces during the plasma treatment. Interest in this process of employing plasma millireactor as a high reactive environment is demonstrated here by the degradation of a volatile organic compound (acetaldehyde) in ambient air. In this miniaturized device, we obtained a high acetaldehyde conversion (98%) for a specific input energy lower than 200 J L(-1).
Red blood cells decorated with functionalized core–shell magnetic nanoparticles: elucidation of the adsorption mechanism
Thanh Duc Mai, Fanny d’Orlye, Christine Ménager, Anne Varenne and Jean-Michel Siaugue
Chem. Comm. - -49 5393—95 - DOI: 10.1039/C3CC41513A - 2013
Microfluidic device with integrated microfilter of conical-shaped holes for high efficiency and high purity capture of circulating tumor cells
Yadong Tang, Jian Shi, Sisi Li, Li Wang, Yvon E. Cayre and Yong Chen
Scientific Reports - 4 (n°6052) - DOI:10.1038/srep06052 - 2013
Capture of circulating tumor cells (CTCs) from peripheral blood of cancer patients has major implications for metastatic detection and therapy analyses. Here we demonstrated a microfluidic device for high efficiency and high purity capture of CTCs. The key novelty of this approach lies on the integration of a microfilter with conical-shaped holes and a micro-injector with cross-flow components for size dependent capture of tumor cells without significant retention of non-tumor cells. Under conditions of constant flow rate, tumor cells spiked into phosphate buffered saline could be recovered and then cultured for further analyses. When tumor cells were spiked in blood of healthy donors, they could also be recovered at high efficiency and high clearance efficiency of white blood cells. When the same device was used for clinical validation, CTCs could be detected in blood samples of cancer patients but not in that of healthy donors. Finally, the capture efficiency of tumor cells is cell-type dependent but the hole size of the filter should be more closely correlated to the nuclei size of the tumor cells. Together with the advantage of easy operation, low-cost and high potential of integration, this approach offers unprecedented opportunities for metastatic detection and cancer treatment monitoring.
Selection Dynamics in Transient Compartmentalization
Alex Blokhuis, David Lacoste, Philippe Nghe, and Luca Peliti
Phys. Rev. Lett. - 120(15) 158101 - doi: 10.1103/PhysRevLett.120.158101 - 2018
Transient compartments have been recently shown to be able to maintain functional replicators in the context of prebiotic studies. Here, we show that a broad class of selection dynamics is able to achieve this goal. We identify two key parameters, the relative amplification of nonactive replicators (parasites) and the size of compartments. These parameters account for competition and diversity, and the results are relevant to similar multilevel selection problems, such as those found in virus-host ecology and trait group selection.
Sign epistasis caused by hierarchy within signalling cascades.
Nghe P, Kogenaru M, Tans S,
Nat Commun - 13;9(1) 1451 - doi: 10.1038/s41467-018-03644-8. - 2018
Sign epistasis is a central evolutionary constraint, but its causal factors remain difficult to predict. Here we use the notion of parameterised optima to explain epistasis within a signalling cascade, and test these predictions in Escherichia coli. We show that sign epistasis arises from the benefit of tuning phenotypic parameters of cascade genes with respect to each other, rather than from their complex and incompletely known genetic bases. Specifically, sign epistasis requires only that the optimal phenotypic parameters of one gene depend on the phenotypic parameters of another, independent of other details, such as activating or repressing nature, position within the cascade, intra-genic pleiotropy or genotype. Mutational effects change sign more readily in downstream genes, indicating that optimising downstream genes is more constrained. The findings show that sign epistasis results from the inherent upstream-downstream hierarchy between signalling cascade genes, and can be addressed without exhaustive genotypic mapping.

346 publications.