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218 results on '"Cayre, Olivier J."'

13. Induced-charge Electrophoresis of Metallo-dielectric Particles

Author

Gangwal, Sumit, Cayre, Olivier J., Bazant, Martin Z., and Velev, Orlin D.

Subjects
Physics - Fluid Dynamics
Abstract

The application of AC electric fields in aqueous suspensions of anisotropic particles leads to unbalanced liquid flows and nonlinear, induced-charge electrophoretic (ICEP) motion. We report experimental observations of the motion of "Janus" microparticles with one dielectric and one metal-coated hemisphere induced by uniform fields of frequency 100 Hz - 10 kHz in NaCl solutions. The motion is perpendicular to the field axis and persists after particles are attracted to a glass wall. This phenomenon may find applications in microactuators, microsensors, and microfluidic devices., Comment: 11 pages, 4 figures; Supplementary Info: Last 2 pages, 2 figures

Published
2007
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17. Effective delivery and selective insecticidal activity of double‐stranded RNA via complexation with diblock copolymer varies with polymer block composition.

Author

Pugsley, Charlotte E., Isaac, R. Elwyn, Warren, Nicholas J., Stacey, Martin, Ferguson, Calum T. J., Cappelle, Kaat, Dominguez‐Espinosa, Rosa, and Cayre, Olivier J.

Subjects
DIBLOCK copolymers, DOUBLE-stranded RNA, BLOCK copolymers, RNA interference, POLYMERS, DROSOPHILA suzukii, SMALL interfering RNA
Abstract

BACKGROUND: Chemical insecticides are an important tool to control damaging pest infestations. However, lack of species specificity, the rise of resistance and the demand for biological alternatives with improved ecotoxicity profiles means that chemicals with new modes of action are required. RNA interference (RNAi)‐based strategies using double‐stranded RNA (dsRNA) as a species‐specific bio‐insecticide offer an exquisite solution that addresses these issues. Many species, such as the fruit pest Drosophila suzukii, do not exhibit RNAi when dsRNA is orally administered due to degradation by gut nucleases and slow cellular uptake pathways. Thus, delivery vehicles that protect and deliver dsRNA are highly desirable. RESULTS: In this work, we demonstrate the complexation of D. suzukii‐specific dsRNA for degradation of vha26 mRNA with bespoke diblock copolymers. We study the ex vivo protection of dsRNA against enzymatic degradation by gut enzymes, which demonstrates the efficiency of this system. Flow cytometry then investigates the cellular uptake of Cy3‐labelled dsRNA, showing a 10‐fold increase in the mean fluorescence intensity of cells treated with polyplexes. The polymer/dsRNA polyplexes induced a significant 87% decrease in the odds of survival of D. suzukii larvae following oral feeding only when formed with a diblock copolymer containing a long neutral block length (1:2 cationic block/neutral block). However, there was no toxicity when fed to the closely related Drosophila melanogaster. CONCLUSION: We provide evidence that dsRNA complexation with diblock copolymers is a promising strategy for RNAi‐based species‐specific pest control, but optimisation of polymer composition is essential for RNAi success. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Published
2024
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50. Polyelectrolyte diode: nonlinear current response of a junction between aqueous ionic gels

Author

Cayre, Olivier J., Suk Tai Chang, and Velev, Orlin D.

Subjects
Polyelectrolytes -- Chemical properties, Anisotropy -- Analysis, Aqueous solution reactions -- Analysis, Chemistry
Abstract

The formation of a fixed rectifying junction between two aqueous gels containing oppositely charged polyelectrolytes is described. The diode prototypes have operated on the counter ionic conductance in the gels and the anisotropic distribution of positive and negative mobile counterions within the device has led to nonlinear current conduction across the gel junction.

Published
2007

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