3 research outputs found
Directed Motion of Metallodielectric Particles by Contact Charge Electrophoresis
We
investigate the dynamics of metallodielectric Janus particles
moving via contact charge electrophoresis (CCEP) between two parallel
electrodes. CCEP uses a constant voltage to repeatedly charge and
actuate conductive particles within a dielectric fluid, resulting
in rapid oscillatory motion between the electrodes. In addition to
particle oscillations, we find that micrometer-scale Janus particles
move perpendicular to the field at high speeds (up to 600 μm/s)
and over large distances. We characterize particle motions and propose
a mechanism based on the rotation-induced translation of the particle
following charge transfer at the electrode surface. The propulsion
mechanism is supported both by experiments with fluorescent particles
that reveal their rotational motions and by simulations of CCEP dynamics
that capture the relevant electrostatics and hydrodynamics. We also
show that interactions among multiple particles can lead to repulsion,
attraction, and/or cooperative motions depending on the position and
phase of the respective particle oscillators. Our results demonstrate
how particle asymmetries can be used to direct the motions of active
colloids powered by CCEP
Directed Motion of Metallodielectric Particles by Contact Charge Electrophoresis
We
investigate the dynamics of metallodielectric Janus particles
moving via contact charge electrophoresis (CCEP) between two parallel
electrodes. CCEP uses a constant voltage to repeatedly charge and
actuate conductive particles within a dielectric fluid, resulting
in rapid oscillatory motion between the electrodes. In addition to
particle oscillations, we find that micrometer-scale Janus particles
move perpendicular to the field at high speeds (up to 600 μm/s)
and over large distances. We characterize particle motions and propose
a mechanism based on the rotation-induced translation of the particle
following charge transfer at the electrode surface. The propulsion
mechanism is supported both by experiments with fluorescent particles
that reveal their rotational motions and by simulations of CCEP dynamics
that capture the relevant electrostatics and hydrodynamics. We also
show that interactions among multiple particles can lead to repulsion,
attraction, and/or cooperative motions depending on the position and
phase of the respective particle oscillators. Our results demonstrate
how particle asymmetries can be used to direct the motions of active
colloids powered by CCEP
Designed Glucopeptides Mimetics of Myelin Protein Epitopes As Synthetic Probes for the Detection of Autoantibodies, Biomarkers of Multiple Sclerosis
We previously reported that CSF114Â(Glc) detects diagnostic
autoantibodies in multiple sclerosis sera. We report herein a bioinformatic
analysis of myelin proteins and CSF114Â(Glc), which led to the identification
of five sequences. These glucopeptides were synthesized and tested
in enzymatic assays, showing a common minimal epitope. Starting from
that, we designed an optimized sequence, SP077, showing a higher homology
with both CSF114Â(Glc) and the five sequences selected using the bioinformatic
approach. SP077 was synthesized and tested on 50 multiple sclerosis
patients’ sera, and was able to detect higher antibody titers
as compared to CSF114Â(Glc). Finally, the conformational properties
of SP077 were studied by NMR spectroscopy and structure calculations.
Thus, the immunological activity of SP077 in the recognition of specific
autoantibodies in multiple sclerosis patients’ sera may be
ascribed to both the optimized design of its epitopic region and the
superior surface interacting properties of its C-terminal region