20 research outputs found
Arrested on heating: controlling the motility of active droplets by temperature
One of the challenges in tailoring the dynamics of active, self-propelling
agents lies in arresting and releasing these agents at will. Here, we present
an experimental system of active droplets with thermally controllable and
reversible states of motion, from unsteady over meandering to persistent to
arrested motion. These states depend on the P\'eclet number of the chemical
reaction driving the motion, which we can tune by using a temperature sensitive
mixture of surfactants as a fuel medium. We quantify the droplet dynamics by
analysing flow and chemical fields for the individual states, comparing them to
canonical models for autophoretic particles. In the context of these models, we
are able to observe in situ the fundamental first transition between the
isotropic, immotile base state and self-propelled motility
Nanoparticles Surface Chemistry Influence on Protein Corona Composition and Inflammatory Responses
Nanoparticles are widely used for biomedical applications such as vaccine, drug delivery, diagnostics, and therapeutics. This study aims to reveal the influence of nanoparticle surface functionalization on protein corona formation from blood serum and plasma and the subsequent effects on the innate immune cellular responses. To achieve this goal, the surface chemistry of silica nanoparticles of 20 nm diameter was tailored via plasma polymerization with amine, carboxylic acid, oxazolines, and alkane functionalities. The results of this study show significant surface chemistry-induced differences in protein corona composition, which reflect in the subsequent inflammatory consequences. Nanoparticles rich with carboxylic acid surface functionalities increased the production of pro-inflammatory cytokines in response to higher level of complement proteins and decreased the number of lipoproteins found in their protein coronas. On another hand, amine rich coatings led to increased expressions of anti-inflammatory markers such as arginase. The findings demonstrate the potential to direct physiological responses to nanomaterials via tailoring their surface chemical composition
Prevention of Dominant IgG Adsorption on Nanocarriers in IgGâEnriched Blood Plasma by Clusterin Precoating
Abstract Nanocarriers for medical applications must work reliably within organisms, independent of the individual differences in the blood proteome. Variation in the blood proteome, such as immunoglobulin levels, is a result of environmental, nutrition, and constitution conditions. This variation, however, should not influence the behavior of nanocarriers in biological media. The composition of the protein corona is investigated to understand the influence varying immunoglobulin levels in the blood plasma have on the interactions with nanocarriers. Specifically, the composition of the nanocarriers' coronas is analyzed after incubation in plasma with normal or elevated immunoglobulin G (IgG) levels, and cellular uptake is monitored in cell lines containing different immunoglobulin receptors. Here, it is reported that upon doubling the IgG concentration in plasma, the IgG fraction in the protein corona increases by a factor of 40 independent of the nanocarrier material. This results in a significant increase in uptake in cells exhibiting IgG binding receptors. Furthermore, precoating nanocarriers with clusterin successfully prevents dominant IgGâadsorption and additionally reduces cellular internalization, after incubation with IgGâenriched plasma. Therefore, precoating nanocarriers may be utilized as a powerful method to reduce the influence of individual variations in blood composition on the protein corona
Datasets underlying the paper Frozen by heating
<p>datasets_repo.zip</p>
<p>Datasets underlying Frozen by heating: temperature controlled dynamic states in droplet microswimmers, arXiv:2303.13442</p>
<p>Source data for all figures in the manuscript. Figures were produced by Python/matplotlib, a corresponding Jupyter notebook is included in the root folder. Raw video data are available from the authors on reasonable request.</p>
<p> </p>
<p>code.zip</p>
<p>Numerical code underlying the simulation data in Fig. 4a.</p>
Polyvinylferrocene-Based Amphiphilic Block Copolymers Featuring Functional Junction Points for Cross-Linked Micelles
The
synthesis of high-molecular-weight, well-defined polyÂ(vinylferrocene)-<i>block</i>-polyÂ(ethylene glycol) (PVFc-<i>b</i>-PEG)
diblock copolymers (<i>M</i><sub>n</sub> = 13âŻ000â44âŻ000
g mol<sup>â1</sup>; <i>Ä</i> = 1.29â1.34)
with precisely one allyl group at the junction point is introduced.
Allyl glycidyl ether (AGE) was used to end-functionalize PVFc, resulting
in hydroxyl functional macroinitiators for the oxyanionic polymerization
of ethylene oxide. The self-assembly behavior of the amphiphilic PVFc-<i>b</i>-PEG copolymers in water has been investigated in a detailed
manner, using dynamic light scattering (DLS) and transmission electron
microscopy (TEM). The redox activity of the PVFc block was confirmed
by UV/vis spectroscopy, while cyclovoltammetry (CV) measurements were
carried out to support the stability and full reversibility of the
ferrocene/ferrocenium redox couple. Both formation and dissociation
of the macromolecular self-assemblies in aqueous solution via oxidation
and reduction of the PVFc segments were evidenced by TEM and DLS.
The dye Nile Red was used as model compound to investigate the stabilization
of a water-insoluble molecule in aqueous solution by the block copolymers
via encapsulation inside micellar structures. Oxidation of the PVFc
segments lead to instantaneous and quantitative release of the dye.
Furthermore, incorporation of the allyl moiety at the block junction
point was used to cross-link the shell of the compartments. By this
strategy a stable incorporation of the dye was achieved while triggered
release via oxidation led to quantitative liberation
Probing nanoparticle-membrane interactions by combining amphiphilic diblock copolymer assembly and plasmonics
International audienceUnderstanding the interactions between nanoparticles (NPs) and boundaries of cells is crucial both for their toxicity and therapeutic applications. Besides specific receptor-mediated endocytosis of surface-functionalized NPs, passive internalization is prompted by relatively unspecific parameters, such as particle size and charge. Based on theoretical treatments, adhesion to and bending of the cell membrane can induce NP wrapping. Experimentally, powerful tools are needed to selectively probe possible membrane-NP motifs at very dilute conditions and avoid dye labeling. In this work, we employ surface resonance-enhanced dynamic light scattering, surface plasmon resonance, electron microscopy, and simulations for sensing interactions between plasmonic AuNPs and polymersomes. We distinguish three different interaction scenarios at nanomolar concentrations by tuning the surface charge of AuNPs and rationalize these events by balancing vesicle bending and electrostatic/van der Waals AuNP and vesicle adhesion. The clarification of the physical conditions under which nanoparticles passively translocate across membranes can aid in the rational design of drugs that cannot exploit specific modes of cellular uptake and also elucidates physical properties that render nanoparticles in the environment particularly toxic
The Transferability from Animal Models to Humans: Challenges Regarding Aggregation and Protein Corona Formation of Nanoparticles
Nanomaterials
are interesting candidates for applications in medicine
as drug delivery or diagnostic agents. For safe application, they
have to be evaluated in in vitro and in vivo models to finally be
translated to human clinical trials. However, often those transfer
processes fail, and it is not completely understood whether in vitro
models leading to these animal models can reliably be compared to
the situation in humans. In particular, the interaction of nanomaterials
with components from different blood plasma sources is difficult to
compare, and the outcomes of those interactions with respect to body
distribution and cell uptake are unclear. Therefore, we investigated
the interactions of differently functionalized polymeric and inorganic
nanoparticles with human, mouse, rabbit, and sheep plasma. The focus
was put on the determination of aggregation events of the nanoparticles
occurring in concentrated plasma and the correlation with the respectively
formed protein coronas. Both the stability in plasma as well as the
types of adsorbed proteins were found to strongly depend on the plasma
source. Thus, we suggest evaluating the potential use of nanocarriers
always in the plasma source of the chosen animal model for in vitro
studies as well as in human plasma to pin down differences and eventually
enable transfer into clinical trials in humans
The Transferability from Animal Models to Humans: Challenges Regarding Aggregation and Protein Corona Formation of Nanoparticles
Nanomaterials
are interesting candidates for applications in medicine
as drug delivery or diagnostic agents. For safe application, they
have to be evaluated in in vitro and in vivo models to finally be
translated to human clinical trials. However, often those transfer
processes fail, and it is not completely understood whether in vitro
models leading to these animal models can reliably be compared to
the situation in humans. In particular, the interaction of nanomaterials
with components from different blood plasma sources is difficult to
compare, and the outcomes of those interactions with respect to body
distribution and cell uptake are unclear. Therefore, we investigated
the interactions of differently functionalized polymeric and inorganic
nanoparticles with human, mouse, rabbit, and sheep plasma. The focus
was put on the determination of aggregation events of the nanoparticles
occurring in concentrated plasma and the correlation with the respectively
formed protein coronas. Both the stability in plasma as well as the
types of adsorbed proteins were found to strongly depend on the plasma
source. Thus, we suggest evaluating the potential use of nanocarriers
always in the plasma source of the chosen animal model for in vitro
studies as well as in human plasma to pin down differences and eventually
enable transfer into clinical trials in humans
Redox-Responsive Block Copolymers: Poly(vinylferrocene)â<i>b</i>âpoly(lactide) Diblock and Miktoarm Star Polymers and Their Behavior in Solution
The synthesis of diblock and miktoarm
star polymers containing
polyÂ(vinylferrocene) (PVFc) and polyÂ(l-lactide) (PLA) blocks
is introduced. End functionalization of PVFc was carried out via end
capping of living carbanionic PVFc chains with benzyl glycidyl ether
(BGE). By hydrogenolysis of the benzyl protecting group a dihydroxyl
end-functionalized PVFc was obtained. Both monohydroxyl- and dihydroxyl-functionalized
PVFcs have been utilized as macroinitiators for the subsequent polymerization
of l-lactide via catalytic ring-opening polymerization. A
series of block copolymers and AB<sub>2</sub> miktoarm star polymers
was synthesized with varied PLA chain lengths. All polymers were characterized
in detail, using <sup>1</sup>H NMR spectroscopy, size exclusion chromatography
(SEC), and matrix-assisted laser desorption/ionization time-of-flight
mass spectrometry (MALDI-ToF). The molecular weight of the block copolymers
and AB<sub>2</sub> miktoarm star polymers are in the range of 8000â15000,
containing a PVFc block of weight 7800. In addition, the self-assembly
behavior of the polymers in dichloromethane (CH<sub>2</sub>Cl<sub>2</sub>) was investigated by using dynamic light scattering (DLS)
and transmission electron microscopy (TEM). In a selective solvent
for PLA the block copolymers and miktoarm star polymers formed vesicle-like
structures with different diameters
Denaturation via Surfactants Changes Composition of Protein Corona
The
use of nanocarriers as drug delivery vehicles brings them into
contact with blood plasma proteins. Polymeric nanocarriers require
some sort of surfactant to ensure colloidal stability. Formation of
the protein corona is therefore determined not only by the intrinsic
properties of the nanocarrier itself but also by the accompanying
surfactant. Although it is well-known that surfactants have an impact
on protein structure, only few studies were conducted on the specific
effect of surfactants on the composition of protein corona of nanocarriers.
Therefore, we analyzed the composition of the protein corona on âstealthâ
nanoparticles with additional surfactant (cetyltrimethylÂammonium
chloride, CTMA-Cl) after plasma incubation. Additional CTMA-Cl led
to an enrichment of apolipoprotein-A1 and vitronectin in the corona,
while less clusterin could be found. Further, the structural stability
of apolipoprotein-A1 and clusterin was monitored for a wide range
of CTMA-Cl concentrations. Clusterin turned out to be more sensitive
to CTMA-Cl, with denaturation occurring at lower concentrations