Phosphonylation Controls the Protein Corona of Multifunctional Polyglycerol‐Modified Nanocarriers

Nanocarriers are a platform for modern drug delivery. In contact with blood, proteins adsorb to nanocarriers, altering their behavior in vivo. To reduce unspecific protein adsorption and unspecific cellular uptake, nanocarriers are modified with hydrophilic polymers like poly(ethylene glycol) (PEG). However, with PEG the attachment of further functional structures such as targeting units is limited. A method to introduce multifunctionality via polyglycerol (PG) while maintaining the hydrophilicity of PEG is introduced. Different amounts of negatively charged phosphonate groups (up to 29 mol%) are attached to the multifunctional PGs (M_n 2–4 kg mol^?1, Ð < 1.36) by post‐modification. PGs are used in the miniemulsion/solvent evaporation procedure to prepare model nanocarriers. Their behavior in human blood plasma is investigated to determine the influence of the negative charges on the protein adsorption. The protein corona of PGylated nanocarriers is similar to PEGylated analogs (on same nanocarriers), but the protein pattern could be gradually altered by the integration of phosphonates. This is the first report on the gradual increase of negative charges on nanocarriers and intriguingly up to a certain amount of phosphonate groups per nanocarrier the protein pattern remains relatively unchanged, which is important for the future design of nanocarriers.     

Carbohydrate‐Based Nanocarriers Exhibiting Specific Cell Targeting with Minimum Influence from the Protein Corona

Whenever nanoparticles encounter biological fluids like blood, proteins adsorb on their surface and form a so‐called protein corona. Although its importance is widely accepted, information on the influence of surface functionalization of nanocarriers on the protein corona is still sparse, especially concerning how the functionalization of PEGylated nanocarriers with targeting agents will affect protein corona formation and how the protein corona may in turn influence the targeting effect. Herein, hydroxyethyl starch nanocarriers (HES‐NCs) were prepared, PEGylated, and modified on the outer PEG layer with mannose to target dendritic cells (DCs). Their interaction with human plasma was then studied. Low overall protein adsorption with a distinct protein pattern and high specific affinity for DC binding were observed, thus indicating an efficient combination of “stealth” and targeting behavior.     

'Stealth' corona-core nanoparticles surface modified by polyethylene glycol (PEG): influences of the corona (PEG chain length and surface density) and of the core composition on phagocytic uptake and plasma protein adsorption

Nanoparticles possessing poly(ethylene glycol) (PEG) chains on their surface have been described as blood persistent drug delivery system with potential applications for intravenous drug administration. Considering the importance of protein interactions with injected colloidal dug carriers with regard to their in vivo fate, we analysed plasma protein adsorption onto biodegradable PEG-coated poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA) and poly(-caprolactone) (PCL) nanoparticles employing two-dimensional gel electrophoresis (2-D PAGE). A series of corona/core nanoparticles of sizes 160–270 nm were prepared from diblock PEG-PLA, PEG-PLGA and PEG-PCL and from PEG-PLA:PLA blends. The PEG Mw was varied from 2000–20 000 g/mole and the particles were prepared using different PEG contents. It was thus possible to study the influence of the PEG corona thickness and density, as well as the influence of the nature of the core (PLA, PLGA or PCL), on the competitive plasma protein adsorption, zeta potential and particle uptake by polymorphonuclear (PMN) cells. 2-D PAGE studies showed that plasma protein adsorption on PEG-coated PLA nanospheres strongly depends on the PEG molecular weight (Mw) (i.e. PEG chain length at the particle surface) as well as on the PEG content in the particles (i.e. PEG chain density at the surface of the particles). Whatever the thickness or the density of the corona, the qualitative composition of the plasma protein adsorption patterns was very similar, showing that adsorption was governed by interaction with a PLA surface protected more or less by PEG chains. The main spots on the gels were albumin, fibrinogen, IgG, Ig light chains, and the apolipoproteins apoA-I and apoE. For particles made of PEG-PLA45K with different PEG Mw, a maximal reduction in protein adsorption was found for a PEG Mw of 5000 g/mole. For nanospheres differing in their PEG content from 0.5 to 20 wt %, a PEG content between 2 and 5 wt % was determined as a threshold value for optimal protein resistance. When increasing the PEG content in the nanoparticles above 5 wt % no further reduction in protein adsorption was achieved. Phagocytosis by PMN studied using chemiluminescence and zeta potential data agreed well with these findings: the same PEG surface density threshold was found to ensure simultaneously efficient steric stabilization and to avoid the uptake by PMN cells. Supposing all the PEG chains migrate to the surface, this would correspond to a distance of about 1.5 nm between two terminally attached PEG chains in the covering ‘brush’. Particles from PEG5K-PLA45K, PEG5K-PLGA45K and PEG5K-PCL45K copolymers enabled to study the influence of the core on plasma protein adsorption, all other parameters (corona thickness and density) being kept constant. Adsorption patterns were in good qualitative agreement with each other. Only a few protein species were exclusively present just on one type of nanoparticle. However, the extent of proteins adsorbed differed in a large extent from one particle to another. In vivo studies could help elucidating the role of the type and amount of proteins adsorbed on the fate of the nanoparticles after intraveinous administration, as a function of the nature of their core. These results could be useful in the design of long circulating intravenously injectable biodegradable drug carriers endowed with protein resistant properties and low phagocytic uptake.     

Dual-functional ROMP-based betaines: effect of hydrophilicity and backbone structure on nonfouling properties

Foundational materials for nonfouling coatings were designed and synthesized from a series of novel dual-functional zwitterionic polymers, Poly[NRZI], which were easily obtained via ring-opening metathesis polymerization (ROMP) followed by a single step transformation of the cationic precursor, Poly[NR(+)], to the zwitterion, Poly[NRZI]. The resulting unique dual-functional structure contained the anion and the cation within the same repeat unit but on separate side chains, enabling the hydrophilicity of the system to be tuned at the repeat unit level. These dual-functional zwitterionic polymers were specifically designed to investigate the impact of structural changes, including the backbone, hydrophilicity, and charge, on the overall nonfouling properties. To evaluate the importance of backbone structure, and as a direct comparison to previously studied methacrylate-based betaines, norbornene-based carbo- and sulfobetaines (Poly[NCarboZI] and Poly[NSulfoZI]) as well as a methacrylate-based sulfobetaine (Poly[MASulfoZI]) were synthesized. These structures contain the anion-cation pairs on the same side chain. Nonfouling coatings were prepared from copolymers, composed of the zwitterionic/cationic precursor monomer and an ethoxysilane-containing monomer. The coatings were evaluated by using protein adsorption studies, which clearly indicated that the overall hydrophilicity has a major influence on the nonfouling character of the materials. The most hydrophilic coating, from the oligoethylene glycol (OEG)-containing dual-functional betaine, Poly[NOEGZI-co-NSi], showed the best resistance to nonspecific protein adsorption (Γ(FIB) = 0.039 ng/mm(2)). Both norbornene-based polymers systems, Poly[NSulfoZI] and Poly[NCarboZI], were more hydrophilic and thus more resistant to protein adsorption than the methacrylate-based Poly[MASulfoZI]. Comparing the protein resistance of the dual-functional zwitterionic coatings, Poly[NRZI-co-NSi], to that of their cationic counterparts, Poly[NR(+)-co-NSi], revealed the importance of screening electrostatic interactions. The adsorption of negatively charged proteins on zwitterionic coatings was significantly less, despite the fact that both coatings had similar wetting properties. These results demonstrate that the unique, tunable dual-functional zwitterionic polymers reported here can be used to make coatings that are highly efficient at resisting protein adsorption.     

Quantitative Protein Corona Composition and Dynamics on Carbon Nanotubes in Biological Environments

When nanoparticles enter biological environments, proteins adsorb to form the “protein corona” which alters nanoparticle biodistribution and toxicity. Herein, we measure protein corona formation on DNA-functionalized single-walled carbon nanotubes (ssDNA-SWCNTs), a nanoparticle used widely for sensing and delivery, in blood plasma and cerebrospinal fluid. We characterize corona composition by mass spectrometry, revealing high-abundance corona proteins involved in lipid binding, complement activation, and coagulation. We investigate roles of electrostatic and entropic interactions driving selective corona formation. Lastly, we study real-time protein binding on ssDNA-SWCNTs, obtaining agreement between enriched proteins binding strongly and depleted proteins binding marginally, while highlighting cooperative adsorption mechanisms. Knowledge of protein corona composition, formation mechanisms, and dynamics informs nanoparticle translation from in vitro design to in vivo application.     

Wettability of proteins adsorbed on silica glasses treated with fluorosurfactants

Generally, the apolar/polar surface is probed by water-wetting, which is measured using a method such as the sessile liquid drop method. However, when one tries to measure the wetting of a surface where biological macromolecules are adsorbed, there is the problem of a change in conformation due to drying the surface; hence, using this method in situ information cannot be obtained. We have developed a new method that can be used to measure the wettability of the adsorbed protein surface without drying. This method, the dropping time method, which is based on measuring the dropping time of a film of liquid along a protein-covered surface when this surface is instantaneously vertically removed from the protein solution. The adsorption behavior of four proteins (albumin, lysozyme, β-lactoglobulin, ovalbumin) on the surface of silica glass that has been treated with various fluorosurfactants is studied using this method. At a high concentration of protein, the surfaces of adsorbed proteins of any kind are fairly hydrophilic on glass treated with all fluorosurfactants. At a lower concentration of protein, the hydrophilicity of the protein layer depends on the kind of fluorosurfactant and also on the protein adsorption process. The apolar glass surface becomes more hydrophilic with increasing dipping time in the protein solution. On the other hand, the hydrophilic glass surface shows a complex change in the hydrophilicity with elapsed time after dipping it into a solution of albumin or lysozyme, i.e., the hydrophilicity decreases in the early stage of the adsorption and then increases with proceeding adsorption. Received: 19 March 1999 Accepted in revised form: 10 June 1999     

Protein resistance of titanium oxide surfaces modified by biologically inspired mPEG-DOPA

In the present study, we have utilized X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry (ELM), and optical waveguide lightmode spectroscopy (OWLS) to examine the surface adsorption and protein resistance behavior of bio-inspired polymers consisting of poly(ethylene glycol) (PEG) conjugated to peptide mimics of mussel adhesive proteins. Peptides containing up to three residues of 3,4-dihydroxyphenylalanine (DOPA), a key component of mussel adhesive proteins, were conjugated to monomethoxy-terminated PEG polymers. These mPEG-DOPA polymers were found to be highly adhesive to TiO2 surfaces, with quantitative XPS analysis providing useful insight into the binding mechanism. Additionally, the antifouling properties of immobilized PEG were reflected in the excellent resistance of mPEG-DOPA-modified TiO2 surfaces to protein adsorption. Measurements of mPEG-DOPA and human serum adsorption were related in terms of ethylene glycol (EG) surface density and serum mass adsorbed and demonstrated a threshold of approximately 15-20 EG/nm2, above which substantially little protein adsorbs. With respect to surface density of adsorbed PEG and the associated nonfouling behavior of the adlayers, strong parallels exist between the nonfouling properties of the surface-bound mPEG-DOPA polymers and PEG polymers immobilized to surfaces using other approaches. Peptide anchors containing three DOPA residues resulted in PEG surface densities higher than those achieved using several existing PEG immobilization strategies, suggesting that peptide mimics of mussel adhesive proteins may be useful for achieving high densities of protein-resistant polymers on surfaces.     

Customized PEG-derived copolymers for tissue-engineering applications

PEG-containing copolymers play a prominent role as biomaterials for different applications ranging from drug delivery to tissue engineering. These custom-designed materials offer enormous possibilities to change the overall characteristics of biomaterials by improving their biocompatibility and solubility, as well as their ability to crystallize in polymer blends and to resist protein adsorption. This article demonstrates various principles of PEG-based material design that are applied to fine tune the properties of biomaterials for different tissue engineering applications. More specifically, strategies are described to develop PEG copolymers with various block compositions and specific bulk properties, including low melting points and improved surface hydrophilicity. Highly hydrated polymer gel networks for promoting cellular growth or suppressing protein adsorption and cell adhesion are introduced. By incorporating selectively cleavable cross-links, these hydrophilic polymers can also serve as smart hydrogel scaffolds, mimicking the natural extracellular matrix for cell cultivation and tissue growth. Ultimately, these developments lead to the creation of biomimetic materials to immobilize bioactive compounds, allowing precise control of cellular adhesion and tissue growth. [image: see text]     

Strategies toward biocompatible artificial implants: Grafting of functionalized poly(ethylene glycol)s to poly(ethylene terephthalate) surfaces

Epoxide and aldehyde end‐functionalized poly(ethylene glycol)s (PEGs) (M_w = 400, 1000, 3400, 5000, and 20,000) were grafted to poly(ethylene terephthalate) (PET) film substrates that contained amine or alcohol groups. PET‐PAH and PET‐PEI were prepared by reacting poly(allylamine) (PAH) and polyethylenimine (PEI) with PET substrates, respectively; PET‐PVOH was prepared by the adsorption of poly(vinyl alcohol) (PVOH) to PET substrates. Grafting was characterized and quantified by the increase of the intensity of the PEG carbon peak in the X‐ray photoelectron spectra. Grafting yield was optimized by controlling reaction parameters and was found to be substrate‐independent in general. Graft density consistently decreased as PEG chain length was increased. This is likely due to the higher steric requirement of higher molecular weight PEG molecules. Water contact angles of surfaces containing long PEG chains (3400, 5000, and 20,000) are much lower than those containing shorter PEG chains (400 and 1000). This indicates that longer PEG chains are more effective in rendering surfaces hydrophilic. Protein adsorption experiments were carried out on PET‐ and PEG‐modified derivatives using collagen, lysozyme, and albumin. After PEG grafting, the amount of protein adsorbed was reduced in all cases. Trends in surface requirements for protein resistance are: surfaces with longer PEG chains and higher chain density, especially the former, are more protein resistant; PEG grafted to surfaces containing branched or network polymers is not effective at covering the underlying substrate, and thus does not protect the entire surface from protein adsorption; and substrates containing surface charge are less protein‐resistant. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5389–5400, 2004     

Surface modification on microfluidic devices with 2-methacryloyloxyethyl phosphorylcholine polymers for reducing unfavorable protein adsorption

Surface modification of polymer materials for preparing microfluidic devices including poly(dimethyl siloxane) (PDMS) was investigated with phospholipids polymers such as poly(2-methacryloyloxylethyl phosphorylcholine(MPC)-co-n-butyl methacrylate) (PMB) and poly(MPC-co-2-ethylhexyl methacrylate-co-2-(N,N-dimethylamino)ethyl methacrylate) (PMED). The hydrophilicity of every surface on the polymer materials modified with these MPC polymers increased and the value of zeta-potential became close to zero. The protein adsorption on the polymer materials with and without the surface modification was evaluated using a protein mixture of human plasma fibrinogen and serum albumin. Amount of proteins adsorbed on these polymeric materials showed significant reduction by the surface modification with the MPC polymers compared to the uncoated surfaces ranging from 56 to 90%. Furthermore, we successfully prepared PDMS-based microchannel which was modified by simple coating with the PMB and PMED. The modified microchannel also revealed a significant reduction of adsorption of serum albumin. We conclude that the MPC polymers are useful for reducing unfavorable protein adsorption on microfluidic devices.     

Polyethylene Glycol Backfilling Mitigates the Negative Impact of the Protein Corona on Nanoparticle Cell Targeting

In protein‐rich environments such as the blood, the formation of a protein corona on receptor‐targeting nanoparticles prevents target recognition. As a result, the ability of targeted nanoparticles to selectively bind to diseased cells is drastically inhibited. Backfilling the surface of a targeted nanoparticle with polyethylene glycol (PEG) molecules is demonstrated to reduce the formation of the protein corona and re‐establishes specific binding. The length of the backfilled PEG molecules must be less than the length of the ligand linker; otherwise, PEG interferes with the binding of the targeting ligand to its corresponding cellular receptor.     

Effect of surface grafted polymers on the adsorption of different model proteins

Adsorption of a model protein to a surface with end-grafted polymers was studied by Monte Carlo simulations. In the model the effect on protein adsorption in the presence of end-grafted polymers was evaluated by calculating the change in free energy between an end-grafted surface and a surface without polymers. The change in free energy was calculated using statistical mechanical perturbation theory. Apart from ordinary athermal polymer-polymer and protein-polymer interactions we also study a broad selection of systems by varying the interaction between proteins and polymers and effective polymer-solvent interactions. The interactions between the molecules span an interval from -0.5 to +0.5 kT. Consequently, general features of protein adsorption to end-grafted surfaces is investigated by systematically changing properties like hydrophilicity/hydrophobicity of the polymer, protein and surface as well as grafting density, degree of polymerization and protein size. Increasing grafting density as well as degree of polymerization decreases the adsorption of protein except in systems with attractive polymer-protein interactions, where adsorption increases with increasing chain length and higher grafting density. At a critical polymer-protein interaction neither chain length nor grafting density affects the free energy of adsorption. Hydrophilic polymers were found to prevent adsorption better than hydrophobic polymers. Very small particles with radii comparable to the size of a polymer segment were, however, better excluded from the surface when using hydrophobic than hydrophilic polymers. For systems with attractive polymer-protein interaction not only the volume of the protein was shown to be of importance but also the size of the exposed surface.     

Physical-chemical aspects of protein corona: relevance to in vitro and in vivo biological impacts of nanoparticles

It is now clearly emerging that besides size and shape, the other primary defining element of nanoscale objects in biological media is their long-lived protein ("hard") corona. This corona may be expressed as a durable, stabilizing coating of the bare surface of nanoparticle (NP) monomers, or it may be reflected in different subpopulations of particle assemblies, each presenting a durable protein coating. Using the approach and concepts of physical chemistry, we relate studies on the composition of the protein corona at different plasma concentrations with structural data on the complexes both in situ and free from excess plasma. This enables a high degree of confidence in the meaning of the hard protein corona in a biological context. Here, we present the protein adsorption for two compositionally different NPs, namely sulfonated polystyrene and silica NPs. NP-protein complexes are characterized by differential centrifugal sedimentation, dynamic light scattering, and zeta-potential both in situ and once isolated from plasma as a function of the protein/NP surface area ratio. We then introduce a semiquantitative determination of their hard corona composition using one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis and electrospray liquid chromatography mass spectrometry, which allows us to follow the total binding isotherms for the particles, identifying simultaneously the nature and amount of the most relevant proteins as a function of the plasma concentration. We find that the hard corona can evolve quite significantly as one passes from protein concentrations appropriate to in vitro cell studies to those present in in vivo studies, which has deep implications for in vitro-in vivo extrapolations and will require some consideration in the future.     

Poly(ethylene glycol) as a biointeractive electron‐beam resist

Poly(ethylene glycol) (PEG) can serve as an electron‐beam (e‐beam) resist to modulate protein adsorption on and cell adhesion to surfaces. PEG preferentially crosslinks under e‐beam irradiation to create microgels with controllable properties. Here, atomic‐force, scanning electron, and confocal microscopies are used to study discrete microgels formed from solvent‐cast PEG thin films by focused e‐beams with energies between 2 and 30 keV and point doses between 10 and 1000 fC. Consistent with experimental findings, Monte Carlo simulation of electron energy deposition identifies three structures within each microgel: a highly crosslinked core near the point of electron incidence; a lightly crosslinked near corona surrounding the core; and a far corona at the PEG–Si interface. The nature and relative sizes of these three regions and, hence, the microgel–protein interactions depend on the incident electron energy and dose. The far corona creates protein‐repulsive surface hundreds of nanometers or more from the microgel core. The highly crosslinked core is largely shielded by the near corona. These findings can help guide the choice of irradiation conditions to most effectively modulate protein–surface interactions via PEG microgels patterned by e‐beam lithography. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1543–1554     

Amphiphilic thermoset elastomers from metal‐free,click crosslinking of PEG‐grafted silicone surfactants

The hydrophobicity of silicone elastomers can compromise their utility in some biomaterials applications. Few effective processes exist to introduce hydrophilic groups onto a polysiloxane backbone and subsequently crosslink the material into elastomers. This problem can be overcome through the utilization of metal‐free click reactions between azidoalkylsilicones and alkynyl‐modified silicones and/or PEGs to both functionalize and crosslink silicone elastomers. Alkynyl‐functional PEG was clicked onto a fraction of the available azido groups of a functional polysiloxane, yielding azido reactive PDMS‐g‐PEG rake surfactants. The reactive polymers were then used to crosslink alkynyl‐terminated PDMS of different molecular weights. Using simple starting materials, this generic yet versatile method permits the preparation and characterization of a library of amphiphilic thermoset elastomers that vary in their composition, crosslink density, elasticity, hydrogel formation, and wettability. An appropriate balance of PEG length and crosslink density leads to a permanently highly wettable silicone elastomer that demonstrated very low levels of protein adsorption. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1082–1093     

Temperature‐Responsive Mixed‐Shell Polymeric Micelles for the Refolding of Thermally Denatured Proteins

We have fabricated a mixed‐shell polymeric micelle (MSPM) that closely mimics the natural molecular chaperone GroEL? GroES complex in terms of structure and functionality. This MSPM, which possesses a shared PLA core and a homogeneously mixed PEG and PNIAPM shell, is constructed through the co‐assembly of block copolymers poly(lactide‐b‐poly(ethylene oxide) (PLA‐b‐PEG) and poly(lactide)‐b‐poly(N‐isopropylacryamide) (PLA‐b‐PNIPAM). Above the lower critical solution temperature (LCST) of PNIPAM, the MSPM evolves into a core–shell–corona micelle (CSCM), as a functional state with hydrophobic PNIPAM domains on its surface. Light scattering (LS), TEM, and fluorescence and circular dichroism (CD) spectroscopy were performed to investigate the working mechanism of the chaperone‐like behavior of this system. Unfolded protein intermediates are captured by the hydrophobic PNIPAM domains of the CSCM, which prevent harmful protein aggregation. During cooling, PNIPAM reverts into its hydrophilic state, thereby inducing the release of the bound unfolded proteins. The refolding process of the released proteins is spontaneously accomplished by the presence of PEG in the mixed shell. Carbonic anhydrase B (CAB) was chosen as a model to investigate the refolding efficiency of the released proteins. In the presence of MSPM, almost 93 % CAB activity was recovered during cooling after complete denaturation at 70 °C. Further results reveal that this MSPM also works with a wide spectrum of proteins with more‐complicated structures, including some multimeric proteins. Given the convenience and generality in preventing the thermal aggregation of proteins, this MSPM‐based chaperone might be useful for preventing the toxic aggregation of misfolded proteins in some diseases.     

Shotgun proteomic analytical approach for studying proteins adsorbed onto liposome surface

The knowledge about the interaction between plasma proteins and nanocarriers employed for in vivo delivery is fundamental to understand their biodistribution. Protein adsorption onto nanoparticle surface (protein corona) is strongly affected by vector surface characteristics. In general, the primary interaction is thought to be electrostatic, thus surface charge of carrier is supposed to play a central role in protein adsorption. Because protein corona composition can be critical in modifying the interactive surface that is recognized by cells, characterizing its formation onto lipid particles may serve as a fundamental predictive model for the in vivo efficiency of a lipidic vector. In the present work, protein coronas adsorbed onto three differently charged cationic liposome formulations were compared by a shotgun proteomic approach based on nano-liquid chromatography–high-resolution mass spectrometry. About 130 proteins were identified in each corona, with only small differences between the different cationic liposome formulations. However, this study could be useful for the future controlled design of colloidal drug carriers and possibly in the controlled creation of biocompatible surfaces of other devices that come into contact with proteins into body fluids.     

Evolution of the protein corona of lipid gene vectors as a function of plasma concentration

The concept that the effective unit of interest in the cell-nanomaterial interaction is the particle and its corona of associated proteins is emerging. Here we investigate the compositional evolution of the protein corona of 1,2-dioleoyl-3-trimethylammonium propane (DOTAP) cationic liposomes (CLs) and DOTAP/DNA lipoplexes over a wide range of plasma concentrations (2.5-80%). The composition of the hard corona of lipoplexes is quite stable, but that of CLs does evolve considerably. We show that the protein corona of CLs is made of both low-affinity and competitive-binding proteins whose relative abundance changes with the plasma concentration. This result may have deep biological implications for the application of lipid-based gene vectors both in vitro and in vivo.     

Human plasma protein adsorption onto dextranized surfaces: a two-dimensional electrophoresis and mass spectrometry study

Protein adsorption is fundamental to thrombosis and to the design of biocompatible materials. We report a two-dimensional electrophoresis and mass spectrometry study to characterize multiple human plasma proteins adsorbed onto four different types of model surfaces: silicon oxide, dextranized silicon, polyurethane and dextranized polyurethane. Dextran was grafted onto the surfaces of silicon and polyurethane to mimic the blood-contacting endothelial cell glycocalyx surface. Surface topography and hydrophobicity/hydrophilicity were determined and analyzed using atomic force microscopy and water contact angle measurements, respectively. Using two-dimensional electrophoresis, we show that, relative to the unmodified surfaces, dextranization significantly inhibits the adsorption of several human plasma proteins including IGHG1 protein, fibrinogen, haptoglobin, Apo A-IV, Apo A-I, immunoglobulin, serum retinal-binding protein and truncated serum albumin. We further demonstrate the selectivity of plasma protein adsorbed onto the different functionalized surfaces and the potential to control and manipulate proteins adsorption on the surfaces of medical devices, implants and microfluidic devices. This result shows that adsorption experiments using a single protein or a binary mixture of proteins are consistent with competitive protein adsorption studies. In summary, these studies indicate that coating blood-contacting biomedical applications with dextran is an effective route to reduce thrombo-inflammatory responses and to surface-direct biological activities.     

聚乙二醇二丁二酸酯的合成

聚乙二醇在药物合成上有很广泛的用途,但其端羟基的活性相对较低,直接应用受到限制.若将羟基活化为羧基则可以扩大其应用范围;尤其是在合成二聚物时,将疏水链换成亲水的聚乙二醇二丁二酸酯链可以增加桥链的亲水性.为此,以聚乙二醇、丁二酸酐为反应物,以吡啶为溶剂,分别合成了一缩二乙二醇二丁二酸酯、二缩三乙二醇二丁二酸酯、三缩四乙二...