The formation of an on-specific protein corona around nanoparticles (NPs) has been identified as one of the culprits for failed nanomedicine.T he amount and type of adsorbed protein from the blood plasma are knownt o determine the fate of NPs and the accessibility of targeting ligands.H erein, we show that the adsorbed protein may not only enlarge the NPs and change their surface properties but also,i nt he case of soft NPs such as polymer micelles,l ead to deformation. Poly(1-O-methacryloyl -b-D-fructopyranose)-bpoly(methylmethacrylate) (P(1-O-MAFru)-b-PMMA) block co-polymers were self-assembled into NPs with as pherical core-shell morphology as determined by small angle neutron scattering (SANS). Upon incubation with albumin, TEM, SANS,a nd small angle X-rays cattering (SAXS) revealed the adsorption of albumin and deformation of the NPs with aspheroid geometry.Removal of the protein led to the reversal of the morphology backt ot he spherical core-shell structure. Structural studies and cell studies of uptake of the NPs imply that the observed deformation mayinfluence blood circulation time and cell uptake.
One can take advantage of the influence of a polymer conjugated with a protein to control the thermal stability and the deployment of the protein. Here, the structural properties are reported of the protein–polymer conjugate myoglobin (Mb)‐poly(ethyl ethylene phosphate) (PEEP) in the native and unfolded conformations, in order to understand the respective roles of the protein and of the polymer size in the stability of the conjugate. The effect is also investigated of the grafting density of the linear biodegradable polyphosphoesters covalently attached to the protein. It is observed that, while the conjugation process at room temperature does not modify the secondary and tertiary structure of the Mb, the unfolding process, as a function of temperature, depends on the grafting density. Small angle neutron scattering reveals that, at room temperature, conjugation does not alter the size of the native protein and that the thickness of the polymer shell around the protein increases as a function of grafting density and of polymer molecular weight. The denatured form of all conjugates is described by an unfolded chain and a correlation length due to the presence of local stiffness.
The supramolecular assembly process is a widespread phenomenon found in both synthetically engineered and naturally occurring systems, such as colloids, liquid crystals, and micelles. However, a basic understanding of the...
This perspective describes advances in determining membrane protein structures in lipid bilayers using small-angle neutron scattering (SANS). Differentially labeled detergents with a homogeneous scattering length density facilitate contrast matching of detergent micelles; this has previously been used successfully to obtain the structures of membrane proteins. However, detergent micelles do not mimic the lipid bilayer environment of the cell membrane in vivo. Deuterated vesicles can be used to obtain the radius of gyration of membrane proteins, but protein-protein interference effects within the vesicles severely limits this method such that the protein structure cannot be modeled. We show herein that different membrane protein conformations can be distinguished within the lipid bilayer of the bicontinuous cubic phase using contrast-matching. Time-resolved studies performed using SANS illustrate the complex phase behavior in lyotropic liquid crystalline systems and emphasize the importance of this development. We believe that studying membrane protein structures and phase behavior in contrast-matched lipid bilayers will advance both biological and pharmaceutical applications of membrane-associated proteins, biosensors and food science.
The formation of an on-specific protein corona around nanoparticles (NPs) has been identified as one of the culprits for failed nanomedicine.T he amount and type of adsorbed protein from the blood plasma are knownt o determine the fate of NPs and the accessibility of targeting ligands.H erein, we show that the adsorbed protein may not only enlarge the NPs and change their surface properties but also,i nt he case of soft NPs such as polymer micelles,l ead to deformation. Poly(1-O-methacryloyl -b-D-fructopyranose)-bpoly(methylmethacrylate) (P(1-O-MAFru)-b-PMMA) block co-polymers were self-assembled into NPs with as pherical core-shell morphology as determined by small angle neutron scattering (SANS). Upon incubation with albumin, TEM, SANS,a nd small angle X-rays cattering (SAXS) revealed the adsorption of albumin and deformation of the NPs with aspheroid geometry.Removal of the protein led to the reversal of the morphology backt ot he spherical core-shell structure. Structural studies and cell studies of uptake of the NPs imply that the observed deformation mayinfluence blood circulation time and cell uptake.
Collagen structure in biological tissues imparts its intrinsic physical properties by the formation of several covalent crosslinks. For the first time, two major crosslinks in the skin dihydroxylysinonorleucine (HLNL) and histidinohydroxymerodesmosine (HHMD), were isotopically labelled and then analysed by liquid-chromatography high-resolution accurate-mass mass spectrometry (LC-HRMS) and small-angle neutron scattering (SANS). The isotopic labelling followed by LC-HRMS confirmed the presence of one imino group in both HLNL and HHMD, making them more susceptible to degrade at low pH. The structural changes in collagen due to extreme changes in the pH and chrome tanning were highlighted by the SANS contrast variation between isotopic labelled and unlabelled crosslinks. This provided a better understanding of the interaction of natural crosslinks with the chromium sulphate in collagen suggesting that the development of a benign crosslinking method can help retain the intrinsic physical properties of the leather. This analytical method can also be applied to study artificial crosslinking in other collagenous tissues for biomedical applications.
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