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by Keyword: Escherichia coli


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Stanton, Morgan M., Simmchen, Juliane, Ma, Xing, Miguel-López, Albert, Sánchez, Samuel, (2016). Biohybrid Janus motors driven by Escherichia coli Advanced Materials Interfaces , 3, (2), 1500505

There has been a significant interest in the development of microswimmers for medical drug and cargo delivery, but the majority of current micromotors rely on toxic fuel sources and materials in their design making them irrelevant for biomedical applications. Bacteria represent an excellent motor alternative, as they are powered using their surrounding biological fluids. For a motile, biohybrid swimmer, Escherichia coli (E. coli) are integrated onto metal capped, polystyrene (PS) Janus particles. Fabrication of the biohybrid is rapid and simple for a microswimmer capable of magnetic guidance and ferrying an anticancer agent. Cell adhesion is regulated as E. coli adheres only to the particle's metal caps allowing the PS surface to be utilized for drug attachment, creating a multifunctional system. E. coli adhesion is investigated on multiple metal caps (Pt, Fe, Ti, or Au) and displays a strong preference to attach to Pt surfaces over other metals. Surface hydrophobicity and surface charge are examined to interpret the cell specific adhesion on the Janus particles. The dual capability of the biohybrid to have guided cell adhesion and localized drug attachment allows the swimmer to have multiple applications for biomedical microswimmers, future bacteria-interface systems, and micro-biorobots.

Keywords: Bacteria adhesion, Biohybrids, Escherichia coli, Janus particles, Microswimmers


del Moral-Zamora, Beatriz, Punter-Villagrassa, Jaime, Oliva-Brañas, Ana M., Álvarez-Azpeitia, Juan Manuel, Colomer-Farrarons, Jordi, Samitier, Josep, Homs-Corbera, Antoni, Miribel-Català, Pere Ll, (2015). Combined dielectrophoretic and impedance system for on-chip controlled bacteria concentration: application to Escherichia coli Electrophoresis , 36, (9-10), 1130-1141

The present paper reports a bacteria autonomous controlled concentrator prototype with a user-friendly interface for bench-top applications. It is based on a micro-fluidic lab-on-a-chip and its associated custom instrumentation, which consists in a dielectrophoretic actuator, to pre-concentrate the sample, and an impedance analyser, to measure concentrated bacteria levels. The system is composed by a single micro-fluidic chamber with interdigitated electrodes and a instrumentation with custom electronics. The prototype is supported by a real-time platform connected to a remote computer, which automatically controls the system and displays impedance data used to monitor the status of bacteria accumulation on-chip. The system automates the whole concentrating operation. Performance has been studied for controlled volumes of Escherichia coli (E. coli) samples injected into the micro-fluidic chip at constant flow rate of 10 μL/min. A media conductivity correcting protocol has been developed, as the preliminary results showed distortion of the impedance analyser measurement produced by bacterial media conductivity variations through time. With the correcting protocol, the measured impedance values were related to the quantity of bacteria concentrated with a correlation of 0.988 and a coefficient of variation of 3.1%. Feasibility of E. coli on-chip automated concentration, using the miniaturized system, has been demonstrated. Furthermore, the impedance monitoring protocol had been adjusted and optimized, to handle changes in the electrical properties of the bacteria media over time.

Keywords: Autonomous Device, Bacteria Concentrator, Dielectrophoresis, Escherichia coli, Impedance Analysis


del Moral Zamora, Beatriz, Manuel Álvarez Azpeitia, Juan, Brañas, Ana Ma Oliva, Colomer-Farrarons, Jordi, Castellarnau, Marc, Miribel-Català, Pere Ll, Homs-Corbera, Antoni, Juárez, Antonio, Samitier, Josep, (2015). Dielectrophoretic concentrator enhancement based on dielectric poles for continuously flowing samples Electrophoresis , 36, (13), 1405-1413

We describe a novel continuous-flow cell concentrator micro-device based on dielectrophoresis (DEP), and its associated custom-made control unit. The performances of a classical interdigitated metal electrode-based DEP microfluidic device and this enhanced version, that includes insulator-based pole structures, were compared using the same setup. Escherichia coli (E. coli) samples were concentrated at several continuous flows and the device's trapping efficiencies were evaluated by exhaustive cell counts. Our results show that pole structures enhance the retention up to 12.6%, obtaining significant differences for flow rates up to 20 μl/min, when compared to an equivalent classical interdigitated electrodes setup. In addition, we performed a subsequent proteomic analysis to evaluate the viability of the biological samples after the long exposure to the actuating electrical field. No E. coli protein alteration in any of the two systems was observed.

Keywords: Concentrator, Dielectrophoresis, Escherichia coli, Lab- on- a- chip


Villar-Pique, A., De Groot, N. S., Sabaté, R., Acebrón, S. P., Celaya, G., Fernàndez-Busquets, X., Muga, A., Ventura, S., (2012). The effect of amyloidogenic peptides on bacterial aging correlates with their intrinsic aggregation propensity Journal of Molecular Biology , 421, (2-3), 270-281

The formation of aggregates by misfolded proteins is thought to be inherently toxic, affecting cell fitness. This observation has led to the suggestion that selection against protein aggregation might be a major constraint on protein evolution. The precise fitness cost associated with protein aggregation has been traditionally difficult to evaluate. Moreover, it is not known if the detrimental effect of aggregates on cell physiology is generic or depends on the specific structural features of the protein deposit. In bacteria, the accumulation of intracellular protein aggregates reduces cell reproductive ability, promoting cellular aging. Here, we exploit the cell division defects promoted by the intracellular aggregation of Alzheimer's-disease-related amyloid β peptide in bacteria to demonstrate that the fitness cost associated with protein misfolding and aggregation is connected to the protein sequence, which controls both the in vivo aggregation rates and the conformational properties of the aggregates. We also show that the deleterious impact of protein aggregation on bacterial division can be buffered by molecular chaperones, likely broadening the sequential space on which natural selection can act. Overall, the results in the present work have potential implications for the evolution of proteins and provide a robust system to experimentally model and quantify the impact of protein aggregation on cell fitness.

Keywords: Amyloid fibrils, Chaperones, Escherichia coli, Inclusion bodies, Protein aggregation