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.     

One-pot Synthesis of PEGylated Gd-based Nanoparticles as High-performance and Biocompatibility Contrast Agents for T1-Weighted Magnetic Resonance Imaging In vivo

Polyethylene glycol modified(PEGylated) NaGdF4(PEG-NaGdF4) nanoparticles as a novel T1-weighted magnetic resonance imaging(MRI) contrast agent was successfully constructed by a one-pot hydrothermal synthesis method. Because of the functionalization of PEG, the nanoprobes had excellent dispersity, excellent stability and high biocompatibility. More importantly, the as-prepared PEG-NaGdF4 nanoprobes revealed the high longitudinal relaxivity value and prominent -weighted MRI contrast performance, which was superior to the commercial MRI contrast agents. With the facile synthesis, excellent dispersity, outstanding stability, remarkable contrast performance and high biocompatibility, the PEGylated NaGdF4 nanoparticles brought more opportunities to the new generation of nanoparticulate-based T1-weighted MRI contrast agents in clinic.     

Targeting of cancer cells using click-functionalized polymer capsules

Targeted delivery of drugs to specific cells allows a high therapeutic dose to be delivered to the target site with minimal harmful side effects. Combining targeting molecules with nanoengineered drug carriers, such as polymer capsules, micelles and polymersomes, has significant potential to improve the therapeutic delivery and index of a range of drugs. We present a general approach for functionalization of low-fouling, nanoengineered polymer capsules with antibodies using click chemistry. We demonstrate that antibody (Ab)-functionalized capsules specifically bind to colorectal cancer cells even when the target cells constitute less than 0.1% of the total cell population. This precise targeting offers promise for drug delivery applications.     

PEGylation of porous silicon using click chemistry

Porous silicon has received considerable interest in recent years in a range of biomedical applications, with its performance determined by surface chemistry. In this work, we investigate the PEGylation of porous silicon wafers using click chemistry. The porous silicon wafer surface chemistry was monitored at each stage of the reaction via photoacoustic Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, whereas sessile drop contact angle and model protein adsorption measurements were used to characterize the final PEGylated surface. This work highlights the simplicity of click-chemistry-based functionalization in tailoring the porous silicon surface chemistry and controlling protein-porous silicon interactions.     

Layer-by-layer assembly of microcapsules and their biomedical applications

Nanoengineered multifunctional capsules with tailored structures and properties are of particular interest due to their multifunctions and potential applications as new colloidal structures in diverse fields. Among the available fabrication methods, the layer-by-layer (LbL) assembly of multilayer films onto colloidal particles followed by selective template removal has attracted extensive attention due to its advantages of precise control over the size, shape, composition, wall thickness and functions of the obtained capsules. The past decade has witnessed a rapid increase of research concerning the new fabrication strategies, functionalization and applications of this kind of capsules, particularly in the biomedical fields such as drug delivery, biosensors and bioreactors. In this critical review, the very recent progress of the multilayer capsules is summarized. First, the advances in assembly of capsules by the LbL technique are introduced with focus on tailoring the properties of hydrogen-bonded multilayer capsules by cross-linking, and fabrication of capsules based on covalent bonding and bio-specific interactions. Then the fabrication strategies which can speed up capsule fabrication are reviewed. In the following sections, the multi-compartmental capsules and the capsules that can transform their shape under stimulus are presented. Finally, the biomedical applications of multilayer capsules with particular emphasis on drug carriers, biosensors and bioreactors are described (306 references).     

Lower rim functionalized resorcinarenes: useful modules for supramolecular chemistry

[formula: see text] A synthetic scheme for the selective functionalization of all-cis (rccc) resorcinarene platform at the "lower rim" was developed. Self-folding and self-complementary cavitands were prepared for molecular recognition and self-assembly, bearing functionality at remote sites. These molecules promise applications on solid support and as polymeric capsules.     

Fabrication of micro reaction cages with tailored properties

Hollow polyelectrolyte capsules in micro- and submicrometer size were prepared. Their interior was functionalized by a "ship in bottle" synthesis of copolymers. While the monomers permeated the capsule wall easily, the formed polymers remained in the capsule cage. The physicochemical properties of the capsule interior such as ion strength, pH, light absorption, and fluorescence could be controlled independently from the surrounding solvent by means of the chemical nature of the captured polymer. In case of polyelectrolytes the osmotic pressure of the counterions led to a swelling of the capsules which can be important for micromechanics. The functionalization with light-sensitive materials allowed selective photoreactions inside the capsules. Synthesis of polyelectrolytes at high concentration resulted in an intertwining of the capsule wall with the polymer. The modified walls behaved like ion exchange membranes and showed selectivity toward adsorption and permeation of organic ions. The modified capsules offer many possibilities for novel applications as containers for controlled precipitation, as nanoreactors for catalyzed reactions, or as sensors.     

Coatings of polyethylene glycol for suppressing adhesion between solid microspheres and flat surfaces

This article describes the development and the examination of surface coatings that suppress the adhesion between glass surfaces and polymer microspheres. Superparamagnetic doping allowed for exerting magnetic forces on the microbeads. The carboxyl functionalization of the polymer provided the means for coating the beads with polyethylene glycol (PEG) with different molecular weight. Under gravitational force, the microbeads settled on glass surfaces with similar polymer coatings. We examined the efficacy of removing the beads from the glass surfaces by applying a pulling force of ~1.2 pN. The percent beads remaining on the surface after applying the pulling force for approximately 5 s served as an indication of the adhesion propensity. Coating of PEG with molecular weight ranging between 3 and 10 kDa was essential for suppressing the adhesion. For the particular substrates, surface chemistry and aqueous media we used, coatings of 5 kDa manifested optimal suppression of adhesion: that is, only 3% of the microbeads remained on the surface after applying the pulling magnetic force. When either the glass or the beads were not PEGylated, the adhesion between them was substantial. Addition of a noncharged surfactant, TWEEN, above its critical micelle concentrations (CMCs) suppressed the adhesion between noncoated substrates. The extent of this surfactant-induced improvement of the adhesion suppression, however, did not exceed the quality of preventing the adhesion that we attained by PEGylating both substrates. In addition, the use of surfactants did not significantly improve the suppression of bead-surface adhesion when both substrates were PEGylated. These findings suggest that such surfactant additives tend to be redundant and that covalently grafted coatings of PEGs with selected chain lengths provide sufficient suppression of nonspecific interfacial interactions.     

Hemocompatibility of poly(vinylidene fluoride) membrane grafted with network-like and brush-like antifouling layer controlled via plasma-induced surface PEGylation

In this work, the hemocompatibility of PEGylated poly(vinylidene fluoride) (PVDF) microporous membranes with varying grafting coverage and structures via plasma-induced surface PEGylation was studied. Network-like and brush-like PEGylated layers on PVDF membrane surfaces were achieved by low-pressure and atmospheric plasma treatment. The chemical composition, physical morphology, grafting structure, surface hydrophilicity, and hydration capability of prepared membranes were determined to illustrate the correlations between grafting qualities and hemocompatibility of PEGylated PVDF membranes in contact with human blood. Plasma protein adsorption onto different PEGylated PVDF membranes from single-protein solutions and the complex medium of 100% human plasma were measured by enzyme-linked immunosorbent assay (ELISA) with monoclonal antibodies. Hemocompatibility of the PEGylated membranes was evaluated by the antifouling property of platelet adhesion observed by scanning electron microscopy (SEM) and the anticoagulant activity of the blood coagulant determined by testing plasma-clotting time. The control of grafting structures of PEGylated layers highly regulates the PVDF membrane to resist the adsorption of plasma proteins, the adhesion of platelets, and the coagulation of human plasma. It was found that PVDF membranes grafted with brush-like PEGylated layers presented higher hydration capability with binding water molecules than with network-like PEGylated layers to improve the hemocompatible character of plasma protein and blood platelet resistance in human blood. This work suggests that the hemocompatible nature of grafted PEGylated polymers by controlling grafting structures gives them great potential in the molecular design of antithrombogenic membranes for use in human blood.     

One‐Pot Fabrication of Rattle‐Like Capsules with Multicores by Pickering‐Based Polymerization with Nanoparticle Nucleation

Rattle‐like polymer capsules with multicores in one shell are facilely fabricated by oil‐in‐water Pickering emulsion polymerization for the first time. The oil phase contains hydrophobic silica nanoparticles dispersed in polymerizable monomer, styrene, and unpolymerizable solvent, hexadecane. The multicore rattle‐like capsules are facilely produced after the polymerization of monomers in the oil droplets. The key point of this one‐pot method lies in the nucleation of hydrophobic silica and the phase separation between the resulting polystyrene and hexadecane. The influences of the contents of silica, hexadecane, cross‐linker, and stabilizer on the structure and morphology of rattle‐like capsules are systematically investigated. Moreover, functionalization of the rattle‐like capsules can be developed easily by varying hydrophobic nucleation nanoparticles in the oil phase. This work opens up a new route to fabricate multilevel capsules or spheres.

     

Solid‐State NMR of PEGylated Proteins

PEGylated proteins are widely used in biomedicine but, in spite of their importance, no atomic‐level information is available since they are generally resistant to structural characterization approaches. PEGylated proteins are shown here to yield highly resolved solid‐state NMR spectra, which allows assessment of the structural integrity of proteins when PEGylated for therapeutic or diagnostic use.     

Elucidation of PEGylation site with a combined approach of in-source fragmentation and CID MS/MS

Poly(ethylene glycol) (PEG)ylation of peptides and proteins creates significant challenges for detailed structural characterization, such as PEG heterogeneity, site of addition and number of attached PEGylated moieties. Recently, we published a novel LC/MS methodology with a post-column addition of amines to obtain accurate masses of PEGylated peptides and proteins. The accurate masses can be used to assign the structures and number of attached PEGs [15], but the PEGylation site remains unclear in situations where multiple potential attachments are involved. Here, we present a methodology combining in-source fragmentation (ISF) with CID-MS/MS to elucidate the PEGylated sites in PEGylated products. All PEGylated samples, either prepared in acidic solution, or collected from a RP-HPLC stream, were first ionized via ISF to produce products containing small PEG fragment attachment, and then those fragment ions obtained were sequenced via CID MS/MS to deduce the PEGylation site. The methodology was successfully applied to PEGylated glucagon and IgG4 antibody light chain, which demonstrated that the small PEG fragments attached were stable during the CID activation.     

自组装共混制备PEG化基因载体

通过含PEG链段的两亲聚合物的自组装共混, 制备了基于疏水作用力的新型PEG化非病毒基因载体. 分别选用胆固醇-聚乙二醇和聚乙二醇-聚丙二醇-聚乙二醇作为共混改性剂, 研究两亲聚合物的种类对组装体在生理盐溶液中的稳定性及基因转染效率的影响. 结果表明, 疏水驱动力的大小是获得稳定的PEG化基因超分子组装体的关键. 通过对两亲聚合物中疏水链段的选择调控, 可制备稳定的PEG化基因超分子组装体, 提高基因传递体系在生理盐溶液中的稳定性及基因转染效率. 通过自组装共混, 为新型PEG化基因超分子组装体的制备提供了切实可行的新方法.     

Purification and analysis of mono‐PEGylated HSA by hydrophobic interaction membrane chromatography

We discuss the purification of mono‐PEGylated HSA by hydrophobic interaction membrane chromatography. The hydrophobicity difference between the different fractionated species was induced by the addition of a lyotropic salt that caused phase transition of PEG (hydrophilic under normal condition) to a mildly hydrophobic form. The HSA PEGylation reaction mixture was mixed with lyotropic salt and passed through a stack of hydrophilized polyvinylidene fluoride membrane discs. Unmodified HSA was obtained in the flow through, while the PEGylated forms of the protein bound to the membrane and could be eluted by reducing the salt concentration. Among the three major PEGylated forms of HSA present in the feed (i.e. mono–, di–, and tri–), mono‐PEGylated HSA was eluted first and could be resolved from the others. The purified material was analyzed by SDS‐PAGE, dynamic light scattering, and SEC combined with multi‐angle light scattering. All these analytical techniques indicated the presence of species that has a molar mass consistent with mono‐PEGylated HSA. A scaled‐down version of the membrane chromatographic methods could be used for the rapid and sensitive analysis of PEGylated proteins.     

One-step synthesis and functionalization of hydroxyl-decorated magnetite nanoparticles

Magnetite nanoparticles covered by a layer of omega-hydroxycarboxylic acid were synthesized in one step by high-temperature decomposition of iron(III) omega-hydroxycarboxylates in tri- and tetra-ethylene glycol. The nanoparticles were characterized by TEM, XRD, IR, XPS and NMR techniques in order to show that they comprise a crystalline magnetite core and actually bear on the outer surface terminal hydroxy groups. The latter ones are convenient "handles" for further functionalization as opposed to the chemically-inert aliphatic chains which cover conventionally synthesized nanoparticles. This was shown by several examples in which the hydroxy groups on the nanoparticle surface were easily transformed in other functional groups or reacted with other molecules. For instance, the hydroxyl-decorated nanoparticles were made water soluble by esterification with a PEGylated acetic acid. The reactive behavior of the surfactant monolayer was monitored by degrading the nanoparticles with aqueous acid and isolating the surfactant for NMR characterization. In general, the reactivity of the terminal hydroxyl groups on the nanoparticle surface parallels that observed in the free surfactants. The reported hydroxyl-decorated magnetite nanoparticles can be thus considered as pro-functional nanoparticles, i.e., a convenient starting material to functionalized magnetic nanoparticles.     

Hydrogen-bonding-driven self-assembly of PEGylated organosilica nanoparticles with poly(acrylic acid) in aqueous solutions and in layer-by-layer deposition at solid surfaces

PEGylated organosilica nanoparticles have been synthesized through self-condensation of (3-mercaptopropyl)trimethoxysilane in dimethyl sulfoxide into thiolated nanoparticles with their subsequent reaction with methoxypoly(ethylene glycol) maleimide. The PEGylated nanoparticles showed excellent colloidal stability over a wide range of pH in contrast to the parent thiolated nanoparticles, which have a tendency to aggregate irreversibly under acidic conditions (pH < 3.0). Due to the presence of a poly(ethylene glycol)-based corona, the PEGylated nanoparticles are capable of forming hydrogen-bonded interpolymer complexes with poly(acrylic acid) in aqueous solutions under acidic conditions, resulting in larger aggregates. The use of hydrogen-bonding interactions allows more efficient attachment of the nanoparticles to surfaces. The alternating deposition of PEGylated nanoparticles and poly(acrylic acid) on silicon wafer surfaces in a layer-by-layer fashion leads to multilayered coatings. The self-assembly of PEGylated nanoparticles with poly(acrylic acid) in aqueous solutions and at solid surfaces was compared to the behavior of linear poly(ethylene glycol). The nanoparticle system creates thicker layers than the poly(ethylene glycol), and a thicker layer is obtained on a poly(acrylic acid) surface than on a silica surface, because of the effects of hydrogen bonding. Some implications of these hydrogen-bonding-driven interactions between PEGylated nanoparticles and poly(acrylic acid) for pharmaceutical formulations are discussed.     

PEG-醛修饰胰岛素产物的构象、纤维化和抗酶解能力

通过圆二色谱分析研究了PEG-醛修饰胰岛素产物在溶液中的构象变化,采用加速振荡实验研究了PEG化对胰岛素纤维化的影响,以体外酶解实验考察了PEG-醛修饰胰岛素产物的抗酶解能力.结果表明,经PEG-醛修饰可以减少胰岛素单体的自缔合,提高胰岛素在溶液中的稳定性,抑制胰蛋白酶和糜蛋白酶对胰岛素的降解.     

Effect of pH and generation of dendron on single‐step synthesis of gold nanoparticles using PEGylated polyamidoamine dendron in aqueous medium

Three types of PEGylated polyamidoamine (PAMAM) dendrons were synthesized through PEGylation of primary amines at the periphery of second, third, and fourth generation dendrons. Au(III) precursors and the synthesized PEGylated PAMAM dendrons were mixed at various pHs to evaluate the effect of pH on gold nanoparticle (Au NP) synthesis by monitoring the change in surface plasmon resonance. The Au NP synthesis reaction was controlled by pH through the balance between protonated and deprotonated tertiary amines and the reactivity of Au(III) precursors. By using PEGylated PAMAM dendrons with higher generation, the obtained Au NPs had narrow size distribution with small average size because of the limitation of intermolecular space among PEGylated PAMAM dendrons for the growth to Au NP. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 1391–1398, 2010     

Gold nanoparticle-loaded PEGylated dendrimers for <Emphasis Type="Italic">theragnosis</Emphasis>

Both therapy and diagnosis, theragnosis, are indispensable for personalized medicine. Gold nanoparticles (Au NPs) have photochemical properties and attenuate X-rays, which are useful for photothermal therapy and X-ray computed tomography (CT) imaging, respectively. Polyethylene glycol (PEG)-modified dendrimers (PEGylated dendrimers) have been used as drug carriers with prolonged blood circulation. In this study, Au NP-loaded PEGylated dendrimers were prepared as agents for photothermal therapy and CT imaging. Au NPs were grown in the PEGylated dendrimer by adding gold ions and reductants under various conditions to improve the properties. Both size and surface plasmon absorption of the Au NPs increased, dependent on the seeding growth conditions. Au NPs with near infrared absorption were also prepared by seeding growth from Au NP-loaded PEGylated dendrimers using formaldehyde. The Au NPs thus grown showed enhanced photothermogenic properties and CT intensities, enabling efficient photocytotoxicity and the enhancement of the blood pool in mice by CT imaging. Therefore, Au NP-loaded PEGylated dendrimers are a potential agent for theragnosis.     

聚乙二醇修饰蛋白体系的SDS-聚丙烯酰胺凝胶电泳染色方法新探

比较了聚乙二醇修饰蛋白体系的SDS-聚丙烯酰胺凝胶电泳(SDS-PAGE)银染、考染、碘化钡染色3种染色方法;提出和比较了银染-碘化钡复染和考染-碘化钡复染2种复染方法.结果表明,银染-碘化钡复染的凝胶中,未修饰蛋白条带消失,PEG修饰蛋白条带保留,游离PEG条带显色;而考染-碘化钡复染的凝胶中,未修饰蛋白、修饰蛋白和游离的PEG条带可同时显色.两种复染方法中,PEG组分的检测限均达到了0.01μg.因此,对PEG修饰蛋白体系的SDS-PAGE可先用考染或银染后再用碘化钡复染,便可在同一块凝胶上先后或同时观察到未修饰蛋白、修饰蛋白和游离PEG的情况,简化了实验操作,方便了实验结果的比较分析.