6 research outputs found
Raw Data in support of 'Evolution and mechanics of mixed phospholipid fibrinogen monolayers' by Ian Williams and Todd M. Squires
Raw data associated with manuscript 'Evolution and mechanics of mixed phospholipid fibrinogen monolayers' by Ian Williams and Todd M. Squires
Coefficients of the stream function from Irreversible particle motion in surfactant-laden interfaces due to pressure-dependent surface viscosity
Coefficients of the stream function solution for the general case of a cylinder within a cylinder enclosing a 2D Newtonian flui
Adsorption Energies of Poly(ethylene oxide)-Based Surfactants and Nanoparticles on an Air–Water Surface
The self-assembly of polymer-based
surfactants and nanoparticles
on fluid–fluid interfaces is central to many applications,
including dispersion stabilization, creation of novel 2D materials,
and surface patterning. Very often these processes involve compressing
interfacial monolayers of particles or polymers to obtain a desired
material microstructure. At high surface pressures, however, even
highly interfacially active objects can desorb from the interface.
Methods of directly measuring the energy which keeps the polymer or
particles bound to the interface (adsorption/desorption energies)
are therefore of high interest for these processes. Moreover, though
a geometric description linking adsorption energy and wetting properties
through the definition of a contact angle can be established for rigid
nano- or microparticles, such a description breaks down for deformable
or aggregating objects. Here, we demonstrate a technique to quantify
desorption energies directly, by comparing surface pressure–density
compression measurements using a Wilhelmy plate and a custom-microfabricated
deflection tensiometer. We focus on polyÂ(ethylene oxide)-based polymers
and nanoparticles. For PEO-based homo- and copolymers, the adsorption
energy of PEO chains scales linearly with molecular weight and can
be tuned by changing the subphase composition. Moreover, the desorption
surface pressure of PEO-stabilized nanoparticles corresponds to the
saturation surface pressure for spontaneously adsorbed monolayers,
yielding trapping energies of ∼10<sup>3</sup> <i>k</i><sub>B</sub><i>T</i>
Adsorption Energies of Poly(ethylene oxide)-Based Surfactants and Nanoparticles on an Air–Water Surface
The self-assembly of polymer-based
surfactants and nanoparticles
on fluid–fluid interfaces is central to many applications,
including dispersion stabilization, creation of novel 2D materials,
and surface patterning. Very often these processes involve compressing
interfacial monolayers of particles or polymers to obtain a desired
material microstructure. At high surface pressures, however, even
highly interfacially active objects can desorb from the interface.
Methods of directly measuring the energy which keeps the polymer or
particles bound to the interface (adsorption/desorption energies)
are therefore of high interest for these processes. Moreover, though
a geometric description linking adsorption energy and wetting properties
through the definition of a contact angle can be established for rigid
nano- or microparticles, such a description breaks down for deformable
or aggregating objects. Here, we demonstrate a technique to quantify
desorption energies directly, by comparing surface pressure–density
compression measurements using a Wilhelmy plate and a custom-microfabricated
deflection tensiometer. We focus on polyÂ(ethylene oxide)-based polymers
and nanoparticles. For PEO-based homo- and copolymers, the adsorption
energy of PEO chains scales linearly with molecular weight and can
be tuned by changing the subphase composition. Moreover, the desorption
surface pressure of PEO-stabilized nanoparticles corresponds to the
saturation surface pressure for spontaneously adsorbed monolayers,
yielding trapping energies of ∼10<sup>3</sup> <i>k</i><sub>B</sub><i>T</i>
Collective Rayleigh-Plateau Instability: A Mimic of Droplet Breakup in High Internal Phase Emulsion
Using a microfluidic multi-inlet
coflow system, we show the Rayleigh-Plateau
instability of adjacent, closely spaced fluid threads to be collective.
Although droplet size distributions and breakup frequencies are unaffected
by cooperativity when fluid threads are identical, breakup frequencies
and wavelengths between mismatched fluid threads become locked due
to this collective instability. Locking narrows the size distribution
of drops that are produced from dissimilar threads, and thus the polydispersity
of the emulsion. These observations motivate a hypothesized two-step
mechanism for high internal phase emulsification, wherein coarse emulsion
drops are elongated into close-packed fluid threads, which break into
smaller droplets via a collective Rayleigh Plateau instability. Our
results suggest that these elongated fluid threads break cooperatively,
whereupon wavelength-locking reduces the ultimate droplet polydispersity
of high-internal phase emulsions, consistent with experimental observations
Platelet-like Nanoparticles: Mimicking Shape, Flexibility, and Surface Biology of Platelets To Target Vascular Injuries
Targeted delivery of therapeutic and imaging agents in the vascular compartment represents a significant hurdle in using nanomedicine for treating hemorrhage, thrombosis, and atherosclerosis. While several types of nanoparticles have been developed to meet this goal, their utility is limited by poor circulation, limited margination, and minimal targeting. Platelets have an innate ability to marginate to the vascular wall and specifically interact with vascular injury sites. These platelet functions are mediated by their shape, flexibility, and complex surface interactions. Inspired by this, we report the design and evaluation of nanoparticles that exhibit platelet-like functions including vascular injury site-directed margination, site-specific adhesion, and amplification of injury site-specific aggregation. Our nanoparticles mimic four key attributes of platelets, (i) discoidal morphology, (ii) mechanical flexibility, (iii) biophysically and biochemically mediated aggregation, and (iv) heteromultivalent presentation of ligands that mediate adhesion to both von Willebrand Factor and collagen, as well as specific clustering to activated platelets. Platelet-like nanoparticles (PLNs) exhibit enhanced surface-binding compared to spherical and rigid discoidal counterparts and site-selective adhesive and platelet-aggregatory properties under physiological flow conditions <i>in vitro</i>. <i>In vivo</i> studies in a mouse model demonstrated that PLNs accumulate at the wound site and induce ∼65% reduction in bleeding time, effectively mimicking and improving the hemostatic functions of natural platelets. We show that both the biochemical and biophysical design parameters of PLNs are essential in mimicking platelets and their hemostatic functions. PLNs offer a nanoscale technology that integrates platelet-mimetic biophysical and biochemical properties for potential applications in injectable synthetic hemostats and vascularly targeted payload delivery