Browse
Submit Data
Databases
API
Help

Dataset Information

25 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Thermoresponsive Nanoparticles with Cyclic-Polymer-Grafted Shells Are More Stable than with Linear-Polymer-Grafted Shells: Effect of Polymer Topology, Molecular Weight, and Core Size.

ABSTRACT: Polymer brush-grafted superparamagnetic iron oxide nanoparticles can change their aggregation state in response to temperature and are potential smart materials for many applications. Recently, the shell morphology imposed by grafting to a nanoparticle core was shown to strongly influence the thermoresponsiveness through a coupling of intrashell solubility transitions and nanoparticle aggregation. We investigate how a change from linear to cyclic polymer topology affects the thermoresponsiveness of poly(2-isopropyl-2-oxazoline) brush-grafted superparamagnetic iron oxide nanoparticles. Linear and cyclic polymers with three different molecular weights (7, 18, and 24.5 kg mol^-1) on two different core sizes (3.7 and 9.2 nm) and as free polymer were investigated. We observed the critical flocculation temperature (CFT) during temperature cycling dynamic light scattering experiments, the critical solution temperature (CST), and the transition enthalpy per monomer during differential scanning calorimetry measurements. When all conditions are identical, cyclic polymers increase the colloidal stability and the critical flocculation temperature compared to their linear counterparts. Furthermore, the cyclic polymer shows only one uniform transition, while we observe multiple transitions for the linear polymer shells. We link the single transition and higher colloidal stability to the absence in cyclic PiPrOx shells of a dilute outer part where the particle shells can interdigitate.

SUBMITTER: Willinger M

PROVIDER: S-EPMC8279546 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Thermoresponsive Polymer Gating System on Mesoporous Shells of Silica Particles Serving as Smart Nanocontainers.

Project description:Spherical silica nanoparticles with solid cores and mesoporous shells (SCMS) were decorated with thermoresponsive polymer brushes that were shown to serve as macromolecular valves to control loading and unloading of a model dye within the mesopores. Thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) brushes were grafted from the surfaces of both solid core (SC) and SCMS particles of similar size using surface-initiated atom transfer radical polymerization. Both systems based on porous (SCMS-PNIPAM) and nonporous (SC-PNIPAM) particles were characterized using cryo-TEM, thermogravimetry and elemental analysis to determine the structure and composition of the decorated nanoparticles. The grafted PNIPAM brushes were found to be responsive to temperature changes enabling temperature-controlled gating of the pores. The processes of loading and unloading in the obtained systems were examined using a model fluorescent dye-rhodamine 6G. Polymer brushes in SCMS-PNIPAM systems were shown to serve as molecular valves enabling significant adsorption (loading) of the dye inside the pores with respect to the SC-PNIPAM (no pores) and SCMS (no valves) systems. The effective unloading of the fluorescent cargo molecules from the decorated nanoparticles was achieved in a water/methanol solution. The obtained SCMS-PNIPAM particles may be used as smart nanocontainers or nanoreactors offering also facile isolation from the suspension due to the presence of dense cores.

| S-EPMC7240617 | biostudies-literature

Highly Stable, Ultrasmall Polymer-Grafted Nanobins (usPGNs) with Stimuli-Responsive Capability.

Project description:Highly stable and stimuli/pH-responsive ultrasmall polymer-grafted nanobins (usPGNs) have been developed by grafting a small amount (10 mol %) of short (4.3 kDa) cholesterol-terminated poly(acrylic acid) (Chol-PAA) into an ultrasmall unilamellar vesicle (uSUV). The usPGNs are stable against fusion and aggregation over several weeks, exhibiting over 10-fold enhanced cargo retention in biologically relevant media at pH 7.4 in comparison with the parent uSUV template. Coarse-grained molecular dynamics (CGMD) simulations confirm that the presence of the cholesterol moiety can greatly stabilize the lipid bilayer. They also show extended PAA chain conformations that can be interpreted as causing repulsion between colloidal particles, thus stabilizing them against fusion. Notably, CGMD predicted a clustering of the Chol-PAA chains on the lipid bilayer under acidic conditions due to intra- and interchain hydrogen bonding, leading to the destabilization of local membrane areas. This explains the experimental observation that usPGNs can be triggered to release a significant amount of cargo upon acidification to pH 5. These developments put the lipid-bilayer-embedded Chol-PAA in stark contrast with traditional poly(acrylic acid) systems where the molar mass (Mn) of the polymer chains must exceed 16.5 kDa to achieve stimuli-responsive changes in conformation. They also distinguish the small usPGNs from the much-larger polymer-caged nanobin platform where the Chol-PAA chains must be covalently cross-linked to engender stimuli-responsive behaviors.

| S-EPMC5990519 | biostudies-literature

Effect of pore diameter on the elution behavior of analytes from thermoresponsive polymer grafted beads packed columns.

Project description:Temperature-responsive chromatography using thermoresponsive polymers is innovative and can control analyte retention via column temperature. Analyte elution behavior in this type of chromatography depends on the modified thermoresponsive polymer and the structure of the base materials. In the present study, we examine the effect of the pore diameter of silica beads on analyte elution behavior in temperature-responsive chromatography. Poly(N-isopropylacrylamide-co-n-butyl methacrylate) hydrogel was applied to beads of various pore sizes: 7, 12, and 30 nm. Almost the same amount of copolymer hydrogel was applied to all beads, indicating that the efficiency of copolymer modification was independent of pore size. Analyte retention on prepared beads in a packed column was observed using steroids, benzodiazepines, and barbiturates as analytes. Analyte retention times increased with temperature on packed columns of 12- and 30-nm beads, whereas the column packed with 7-nm beads exhibited decreased retention times with increasing temperature. The difference in analyte elution behavior among the various pore sizes was attributed to analyte diffusion into the bead pores. These results demonstrate that bead pore diameter determines temperature-dependent elution behavior.

| S-EPMC8113370 | biostudies-literature

Polymer Topology Determines the Formation of Protein Corona on Core-Shell Nanoparticles.

Project description:Linear and cyclic poly(2-ethyl-2-oxazoline) (PEOXA) adsorbates provide excellent colloidal stability to superparamagnetic iron oxide nanoparticles (FexOy NPs) within protein-rich media. However, dense shells of linear PEOXA brushes cannot prevent weak but significant attractive interactions with human serum albumin. In contrast, their cyclic PEOXA counterparts quantitatively hinder protein adsorption, as demonstrated by a combination of dynamic light scattering and isothermal titration calorimetry. The cyclic PEOXA brushes generate NP shells that are denser and more compact than their linear counterparts, entirely preventing the formation of a protein corona as well as aggregation, even when the lower critical solution temperature of PEOXA in a physiological buffer is reached.

| S-EPMC7596783 | biostudies-literature

Thermoresponsive Core-Shell Nanoparticles: Does Core Size Matter?

Project description:Nanoparticles grafted with a dense brush of hydrophilic polymers exhibit high colloidal stability. However, reversible aggregation can be triggered by an increase in temperature if the polymer is thermoresponsive, as the polymer shell partly loses its hydration. We investigate the role of nanoparticle curvature on the critical solution temperature (CST) of grafted poly(2-isopropyl-2-oxazoline) (PiPOx) and critical flocculation temperature (CFT) of the core-shell nanoparticle dispersion. Cores with diameters ranging from 5 to 21 nm were studied by temperature-cycled dynamic light scattering and differential scanning calorimetry over a large range of concentrations. We show that core size and curvature only have a minor influence on particle aggregation (CFT and cluster size), while they have major influence on the CST of the polymer shell. The densely grafted shells exhibit three distinct solvation transitions, the relative contributions of each is controlled by the core curvature. We link these transitions to different polymer density regimes within the spherical brush and demonstrate that the CST of the innermost part of the brush coincides with the CFT of the particle dispersion.

| S-EPMC6163620 | biostudies-literature

Dependence of pharmacokinetics and biodistribution on polymer architecture: effect of cyclic versus linear polymers.

Project description:The ability of a polymer to reptate through a nanopore has an influence on its circulatory half-life and biodistribution, since many physiological barriers contain nanopores. A cyclic polymer lacks chain ends, and therefore, cyclic polymers with molecular weights greater than the renal threshold for elimination should circulate longer than their linear-polymer counterparts when injected into animals. As predicted, radiolabeled cyclic polymers with molecular weights greater than the renal threshold have longer blood circulation times in mice than do linear polymers of comparable molecular weight.

| S-EPMC2668136 | biostudies-literature

Formation of neural networks with structural and functional features consistent with small-world network topology on surface-grafted polymer particles.

Project description:In vitro electrophysiological investigation of neural activity at a network level holds tremendous potential for elucidating underlying features of brain function (and dysfunction). In standard neural network modelling systems, however, the fundamental three-dimensional (3D) character of the brain is a largely disregarded feature. This widely applied neuroscientific strategy affects several aspects of the structure-function relationships of the resulting networks, altering network connectivity and topology, ultimately reducing the translatability of the results obtained. As these model systems increase in popularity, it becomes imperative that they capture, as accurately as possible, fundamental features of neural networks in the brain, such as small-worldness. In this report, we combine in vitro neural cell culture with a biologically compatible scaffolding substrate, surface-grafted polymer particles (PPs), to develop neural networks with 3D topology. Furthermore, we investigate their electrophysiological network activity through the use of 3D multielectrode arrays. The resulting neural network activity shows emergent behaviour consistent with maturing neural networks capable of performing computations, i.e. activity patterns suggestive of both information segregation (desynchronized single spikes and local bursts) and information integration (network spikes). Importantly, we demonstrate that the resulting PP-structured neural networks show both structural and functional features consistent with small-world network topology.

| S-EPMC6837210 | biostudies-literature

Polymer-supported lipid shells, onions, and flowers.

Project description:Phospholipid-enveloped biodegradable polymer microparticles and nanoparticles synthesized by an emulsion/solvent evaporation process were characterized by confocal and cryoelectron microscopies to show that the lipid envelope exhibits two-dimensional fluidity and can be configured into 'shell', 'onion', or 'flower' nanostructures, depending on the quantity and composition of lipids employed in the synthesis.

| S-EPMC2743563 | biostudies-literature

Structure of Polymer-Grafted Nanoparticle Melts.

Project description:The structure of neat melts of polymer-grafted nanoparticles (GNPs) is studied via coarse-grained molecular dynamics simulations. We systematically vary the degree of polymerization and grafting density at fixed nanoparticle (NP) radius and study in detail the shape and size of the GNP coronas. For sufficiently high grafting density, chain sections close to the NP core are extended and form a dry layer. Further away from the NP, there is an interpenetration layer, where the polymer coronas of neighboring GNPs overlap and the chain sections have almost unperturbed conformations. To better understand this partitioning, we develop a two-layer model, representing the grafted polymer around an NP by spherical dry and interpenetration layers. This model quantitatively predicts that the thicknesses of the two layers depend on one universal parameter, x, the degree of overcrowding of grafted chains relative to chains in the melt. Both simulations and theory show that the chain extension free energy is nonmonotonic with increasing chain length at a fixed grafting density, with a well-defined maximum. This maximum is indicative of the crossover from the dry layer-dominated to interpenetration layer-dominated regime, and it could have profound consequences on our understanding of a variety of anomalous transport properties of these GNPs. Our theoretical approach therefore provides a facile means for understanding and designing solvent-free GNP-based materials.

| S-EPMC8056455 | biostudies-literature

Tuning the Size of Thermoresponsive Poly(N-Isopropyl Acrylamide) Grafted Silica Microgels.

Project description:Core-shell microgels were synthesized via a free radical emulsion polymerization of thermoresponsive poly-(N-isopropyl acrylamide), pNipam, on the surface of silica nanoparticles. Pure pNipam microgels have a lower critical solution temperature (LCST) of about 32 °C. The LCST varies slightly with the crosslinker density used to stabilize the gel network. Including a silica core enhances the mechanical robustness. Here we show that by varying the concentration gradient of the crosslinker, the thermoresponsive behaviour of the core-shell microgels can be tuned. Three different temperature scenarios have been detected. First, the usual behaviour with a decrease in microgel size with increasing temperature exhibiting an LCST; second, an increase in microgel size with increasing temperature that resembles an upper critical solution temperature (UCST), and; third, a decrease with a subsequent increase of size reminiscent of the presence of both an LCST, and a UCST. However, since the chemical structure has not been changed, the LCST should only change slightly. Therefore we demonstrate how to tune the particle size independently of the LCST.

| S-EPMC6318582 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data