Poly(ethylene Glycol) Methyl Ether Methacrylate Research Articles

Functional 2-methylene-1,3-dioxepane terpolymer: a versatile platform to construct biodegradable polymeric prodrugs for intracellular drug delivery

Functional 2-methylene-1,3-dioxepane (MDO) terpolymers were explored here as a versatile platform to construct biodegradable pH sensitive polymeric prodrugs for intracellular drug delivery. A series of MDO-based biodegradable functional polyester P(MDO-co-PEGMA-co-PDSMA) with different compositions were synthesized by terpolymerization of MDO, poly(ethylene glycol) methyl ether methacrylate (PEGMA) and pyridyldisulfide ethylmethacrylate (PDSMA) via a simple one-pot radical ring-opening copolymerization. Mal-DOX, which contains a pH-sensitive hydrazone bond between doxorubicin (DOX) and the maleimide group, was covalently conjugated in one pot to free thiol groups of PDSMA units via thiol–ene click chemistry in the presence of tri(2-carboxyethyl)phosphine (TCEP). The DOX-conjugated P(MDO-co-PEGMA-co-PDSMA) can self-assemble into prodrug micelles. The diameter and morphology of the polymeric prodrug micelles were measured by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Because of the existence of the pH-sensitive hydrazone bonds, in vitro drug release results showed that the release of DOX was much faster at pH 5.5 than that at pH 7.4. Flow cytometry and fluorescence microscopy demonstrated that the prodrug micelles could be efficiently internalized by cancer cells. In vitro cytotoxicity showed that the DOX-conjugated prodrug micelles can strongly inhibit the proliferation of cancer cells remarkably. Importantly, this work provides a versatile strategy for the fabrication of biodegradable polymeric prodrug nanocarriers.

Preparation and ionic conductivity of composite polymer electrolytes based on hyperbranched star polymer

Hyperbranched star polymer HBPS-(PPEGMA) x was synthesized by atom transfer radical polymerization (ATRP) using hyperbranched polystyrene (HBPS) as macroinitiator and poly(ethylene glycol) methyl ether methacrylate (PEGMA) as monomer. The structure of the prepared hyperbranched star polymer was characterized by 1H NMR, ATR-FTIR, and GPC. Polymer electrolytes based on HBPS-(PPEGMA) x , lithium salt, and/or nano-TiO2 were prepared. The influences of lithium salt concentration and type, nano-TiO2 content, and size on ionic conductivity of the obtained polymer electrolytes were investigated. The results showed that the low crystallinity of the prepared polymer electrolyte was caused by the interaction between lithium salt and polymer. The addition of TiO2 into HBPS-(PPEGMA) x /LiTFSI improved the ionic conductivity at low temperature. The prepared composite polymer electrolyte showed the highest ionic conductivity of 9 × 10−5 S cm−1 at 30 °C when the content of TiO2 was 15 wt% and the size of TiO2 was 20 nm.

Synthesis via RAFT polymerization of thermo- and pH-responsive random copolymers containing cholic acid moieties and their self-assembly in water

Here we report the design and synthesis of polymers containing cholic acid pendant groups, a major bile acid synthesized in the liver from cholesterol. Random copolymers derived from 2-(methacryloyloxy)ethyl cholate (MAECA) with polyethylene glycol methyl ether methacrylate (PEGMA) and N,N-dimethylaminoethyl methacrylate (DMAEMA) have been synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization. Compositions of co-monomers in the copolymers were determined by 1H NMR spectroscopy, which were further used to determine reactivity ratios of the monomers using the extended Kelen–Tudos method at high conversions. Copolymers from MAECA with PEGMA (P(MAECA-co-PEGMA)) series displayed lower critical solution temperatures (LCSTs) up to 23% MAECA content in the copolymer, which was studied by UV-visible spectroscopy. Both thermo- and pH-responsiveness were observed for the P(MAECA-co-DMAEMA) copolymers with an MAECA unit in the copolymer up to 11.8%. The critical aggregation concentration (CAC) of water soluble copolymers was determined by fluorescence spectroscopy. Self-assembly of random copolymers was investigated by 1H NMR spectroscopy, dynamic light scattering (DLS), atomic force microscopy (AFM) and scanning electron microscopy (SEM), which indicated micellar structures in water from cholic acid based random copolymers. The polymeric aggregates were further explored for their drug encapsulation capabilities in aqueous medium using nile red as a hydrophobic model compound.

A Polyrotaxane-based pH-labile Drug Delivery System

A novel polyrotaxane (PR)-based triblock copolymer was exploited as polymeric carrier for doxorubicin (DOX). A sample holding a feed molar ratio of Pluronic F127 to β-CD to poly(ethylene glycol) methyl ether methacrylate (PEGMA) equal to 1:30:20 was synthesized via the in situ atom transfer radical polymerization (ATRP) and then conjugated with DOX using pH sensitive hydrazone linker. The resulting PR-DOX conjugates enabled to self-assemble into nano-particles of about 70 nm in diameter in aqueous solution as evidenced by TEM. The release of DOX was varied from 10 % to 37 % over 72 h at physiological and acidic pH, respectively. The PR-based triblock copolymer without DOX conjugation showed almost non toxicity, while these nano-particles with DOX conjugation presented increased toxicity.

Synthesis and Characterization of PEGylated Brush-type Polycation Modified with Galactosamine

Gene therapy has been generally regarded as a promising treatment for numerous hard curable diseases, such as cancer, genetic and infectious diseases. Seeking a safe and efficient vector plays the most challenging role in gene therapy. In the past decades, non-viral polycation has attracted much more attentions as a promising gene vector due to their good biocompatibility, high condensation ability, as well as easily-adjustable and controlled structures. In the present work, a series of galactosamine (Gal)-conjugated brush-type cationic copolymer P(PEGMEMA-co-PEGMA-Gal)-b-PDMAEMA were prepared via a combination of two-step atom transfer radical polymerization (ATRP) technique and polymer reaction. Firstly, random copolymerization of poly(ethylene glycol)methyl ether methacrylate (PEGMEMA) and poly(ethylene glycol) methacrylate (PEGMA) was carried out to yield the copolymer P(PEGMEMA-co-PEGMA), which was further used as a macroinitiator to polymerize 2-(N ,N-dimethylamino)ethyl methacrylate (DMAEMA), producing the cationic copolymer P(PEGMEMA-co-PEGMA)-b-PDMAEMA. Finally, the brush-type copolymer P(PEGMEMA-co-PEGMA-Gal)-bPDMAEMA was obtained by the modification of pendent hydroxyl groups with galactosamine using N,N'-carbonyldiimidazole (CDI) as the coupling agent. PDMAEMA is a well-known pH-sensitive polycation and has been widely applied for non-viral gene delivery, while the brush-type hydrophilic chains provide the carrier with favorable biocompatibility, prolonged blood circulation time, and reduced non-specific adsorption of proteins. PDMAEMA block would be partially protonated to afford some hydrophobic domains and positive charges at neutral condition, which can bind with DNA via electrostatic interaction to form polycation/DNA polyplex. The Gal moiety on the surface made the polyplex easily recognized by asialoglycoprotein receptors (ASGPRs) over-expressing hepatoma cells and internalized via a receptor-mediated endocytosis process. The chemical structures, molecular weights and molecular weight distributions of P(PEGMEMA-co-PEGMA-Gal)-b-PDMAEMA copolymer were characterized by H NMR, FT-IR, and GPC measurements. The DNA binding capacity of this copolymer was investigated by agarose gel electrophoresis and zeta potential measurements, which indicated that DNA migration could be completely retarded when the N/P ratio was higher than 1.5. The DLS DOI: 10.6023/A14030185

A facile approach toward protein-resistant biointerfaces based on photodefinable poly-p-xylylene coating

A facile and versatile tool is reported that uses a photodefinable polymer, poly(4-benzoyl-p-xylylene-co-p-xylylene) to immobilize antifouling materials, such as poly(ethylene glycol), poly(ethylene glycol) methyl ether methacrylate, dextran, and ethanolamine. This immobilization process requires the polymer's photoactivated carbonyl groups, which can facilitate light-induced molecular crosslinking and can rapidly react via insertion into CH or NH bonds upon photo-illumination at 365nm. Importantly, the process does not require additional functional groups on the antifouling materials. The immobilized fouling materials were characterized using X-ray photoelectron spectroscopy (XPS) and infrared reflection absorption spectroscopy (IRRAS), and the resulting antifouling properties were examined through protein adsorption studies on fibrinogen and bovine serum albumin at surfaces that were spatially modified using a photomask during the photochemical process. In addition, the adsorbed fibrinogen was quantitatively analyzed using a quartz crystal microbalance (QCM), and the adsorption values were reduced to 32.8±4.9ngcm−2, 5.5±3.9ngcm−2, 21.4±4.5ngcm−2, and 16.9±3.4ngcm−2 for poly(ethylene glycol) (PEG), poly(ethylene glycol) methyl ether methacrylate (PEGMA), dextran, and ethanolamine, respectively. Finally, this antifouling modification technology was demonstrated on an unconventional substrate for a stent that was modified by PEGMA at selected areas using a microscopic patterning technique during photoimmobilization. Low levels of fibrinogen and BSA adsorption were also observed at the areas where PEGMA was attached.

Argon Plasma-Induced Graft Polymerization of PEGMA on Chitosan Membrane Surface for Cell Adhesion Improvement

For its biocompatibility and biodegradability, chitosan has had considerable attention for biomedical applications in recent years. In this paper, polymerization of poly (ethylene glycol) methyl ether methacrylate (PEGMA) was grafted onto chitosan membrane surface through argon plasma-induced graft polymerization. The surface properties after modification were characterized by contact angle measurement, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), respectively. The results indicated that PEGMA can be grafted successfully onto chitosan membrane surface. The surface hydrophilicity and free energy were improved and the surface roughness increased after modification. The adhesion of a human corneal epithelial cell (HCEC) on chitosan membrane surface was enhanced due to improvement of surface free energy and roughness.

Fabrication of Contrast Agents for Magnetic Resonance Imaging from Polymer-Brush-Afforded Iron Oxide Magnetic Nanoparticles Prepared by Surface-Initiated Living Radical Polymerization

The aim of this study is to fabricate a contrast agent for magnetic resonance imaging (MRI) by using hybrid particles composed of a core of iron oxide magnetite (Fe3O4) nanoparticles and a shell of hydrophilic polymer brush synthesized by surface-initiated (SI) living radical polymerization. To achieve this, Fe3O4 nanoparticles were surface-modified with initiating groups for atom transfer radical polymerization (ATRP) via a ligand-exchange reaction in the presence of a triethoxysilane derivative having an ATRP initiation site. The ATRP-initiator-functionalized Fe3O4 nanoparticles were used for performing the SI-ATRP of methyl methacrylate to demonstrate the ability of the synthesized nanoparticles to produce well-defined polymer brushes on their surfaces. The polymerization proceeded in a living fashion so as to produce graft polymers with targeted molecular weights and narrow molecular weight distribution. The average graft density was estimated to be as high as 0.7 chains/nm(2), which indicates the formation of so-called concentrated polymer brushes on the Fe3O4 nanoparticles. Dynamic light scattering and transmission electron microscope observations of the hybrid nanoparticles revealed their uniformity and dispersibility in solvents to be excellent. A similar polymerization process was conducted using a hydrophilic monomer, poly(ethylene glycol) methyl ether methacrylate (PEGMA), to prepare Fe3O4 nanoparticles grafted with poly(PEGMA) brushes. The resultant hybrid nanoparticles showed excellent dispersibility in aqueous media including physiological conditions without causing any aggregations. The blood clearance and biodistribution of the hybrid particles were investigated by intravenously injecting particles labeled with a radio isotope, (125)I, into mice. It was found that some hybrid particles exhibited an excellently prolonged circulation lifetime in the blood with a half-life of about 24 h. When such hybrid particles were injected intravenously into a tumor-bearing mouse, they preferentially accumulated in the tumor tissues owing to the so-called enhanced permeability and retention effect. The tumor-targeted delivery was visualized by a T2-enhaced MRI measurement.

Preparation of solid-state composite electrolytes based on organic/inorganic hybrid star-shaped polymer and PEG-functionalized POSS for all-solid-state lithium battery applications

A series of composite electrolytes (CEs) consisting of organic/inorganic hybrid star-shaped polymer (SPP13), plasticizer (PEG-functionalized POSS derivatives), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were prepared to investigate the effects of the composite compositions and PEG chain length of PEs on the properties of CEs. SPP13 was prepared via ATRP from poly(ethylene glycol) methyl ether methacrylate (PEGMA) and methacryl-cyclohexyl-POSS (MA-POSS) using an octafunctional initiator, and the PEG-functionalized POSS derivatives were synthesized by the hydrosilylation reaction of octakis(dimethylsilyloxy)silsesquioxane (OHPS) and allyl-PEG. The CEs were found to be dimensionally-stable enough to separate the electrodes in batteries, but they still possessed high mobility of ion-conducting P(PEGMA) segments, as estimated by the low glass transition temperatures (Tg). The CEs having solid-state show quite high ionic conductivity (4.5 × 10−5 S cm−1 at 30 °C) which is about three times of magnitude larger than that of the matrix polymer (SPP13) electrolyte (1.5 × 10−5 S cm−1 at 30 °C). The CEs were electrochemically stable up to +4.2 V without the decomposition of electrolytes. An all-solid-state lithium battery prepared from the CEs exhibited larger discharge capacity than that prepared from the SPP13 electrolyte at 60 °C.

Poly(vinylcaprolactam)-Based Biodegradable Multiresponsive Microgels for Drug Delivery

Poly(vinylcaprolactam) (PVCL)-based biodegradable microgels were prepared for the biomedical application as drug delivery system via precipitation polymerization, where N,N-bis(acryloyl) cystamine (BAC) served as cross-linker, methacrylic acid (MAA) and polyethylene glycol (PEG) methyl ether methacrylate acted as comonomers. The microgels with excellent stability had distinct temperature sensitivity as largely observed in the case of PVCL-based particles and their volume phase transition temperature (VPTT) shifted to higher temperature with increasing MAA content and ambient pH. In the presence of reducing agent glutathione (GSH) or dithiothreitol (DTT), the microgels could be degraded into individual linear polymer chains by the cleavage of the disulfide linkages coming from the cross-linker BAC. The microgels could effectively encapsulate Doxorubicin (DOX) inside and presented stimuli-triggered drug release in acidic or reducing environment. The results of the cytotoxicity assays further demonstrated that the blank microgels were nontoxic to normal cells while DOX-loaded microgels presented efficient antitumor activity to HeLa cells.

Robust grafting of PEG-methacrylate brushes from polymeric coatings

A study is presented of the grafting of poly(ethylene glycol)methyl ether methacrylate (PEGMA) from polymeric macroinitiator films to form well-defined polymer brushes, using activators generated/regenerated by electron transfer (AGET/ARGET) atom transfer radical polymerization (ATRP). Polymer brush coatings can potentially be obtained on surfaces of virtually any shape and composition, because of the ease of conformal casting of the anchoring macroinitiator film. Polymer brush coatings are synthesized in a robust way, as ARGET and AGET ATRP require little to no deoxygenation and make use of stable catalysts. The monomer, catalyst, ligand and reducing agent concentrations, the amount and type of initiating moiety in the anchoring films, and the choice of solvents are optimized, resulting in control over the rate of reaction, and the molecular weight of poly(PEGMA). The best conditions are determined for the formation of a poly(PEGMA) brush with high grafting density, controlled thickness and “living” ends available for post-functionalization.

A tumor-targeting nano doxorubicin delivery system built from amphiphilic polyrotaxane-based block copolymers

Amphiphilic polyrotaxane (PR)-based block copolymers are synthesized by end-capping polypseudorotaxanes (PPRs) formed from distal 2-bromopropionyl terminated Pluronic F68 and a varying amount of β-cyclodextrins (β-CDs) using hydrophilic polymeric blocks of poly(ethylene glycol) methyl ether methacrylate (PEGMA) yielded via the in situ ATRP. To gain a tumor-targeting nano doxorubicin (DOX) delivery system for cancer chemotherapy, an active tumor-targeting ligand, folic acid (FA), is conjugated to the two ends of the resulting copolymers through “azide-ethylene click chemistry”. The conjugated copolymers enable to self-assemble into unique core–shell structured micelles in aqueous solution and to load DOX into the hydrophobic core. The drug loading content is increased from 2.0 wt% to 25.5 wt% with respect to the blank block copolymer most likely due to the hydrogen bond interaction between DOX and β-CDs threaded. After drug loading, the size of the micelles is enlarged from 120 nm to 220 nm in diameter as determined by dynamic light scattering (DLS) analysis. Moreover, these tumor-targeted polymeric micelles exhibit a slower and sustained DOX release behavior. The cell uptake and distribution, as well as the cytotoxicity of the polymeric micelles are also evaluated toward the MDA-MB-231 cells. The FA-conjugated PR-based block copolymer micelles appear to be internalized by the cancer cells via FA receptor mediated endocytosis; thus, they present enhanced cytotoxicity to the selected breast cancer cells.

Hemoglobin and Red Blood Cells Catalyze Atom Transfer Radical Polymerization

Hemoglobin (Hb) is a promiscuous protein that not only transports oxygen, but also catalyzes several biotransformations. A novel in vitro catalytic activity of Hb is described. Bovine Hb and human erythrocytes were found to display ATRPase activity, i.e., they catalyzed the polymerization of vinyl monomers under conditions typical for atom transfer radical polymerization (ATRP). N-isopropylacrylamide (NIPAAm), poly(ethylene glycol) methyl ether acrylate (PEGA), and poly(ethylene glycol) methyl ether methacrylate (PEGMA) were polymerized using organobromine initiators and the reducing agent ascorbic acid in acidic aqueous solution. In order to avoid chain transfer from polymer radicals to Hb's cysteine residues, the accessible cysteines were blocked by a reaction with a maleimide. The formation of polymers with bromine chain ends, relatively low polydispersity indices (PDI), first order kinetics and an increase in the molecular weight of poly(PEGA) and poly(PEGMA) upon conversion indicate that control of the polymerization by Hb occurred via reversible atom transfer between the protein and the growing polymer chain. For poly(PEGA) and poly(PEGMA), the reactions proceeded with a good to moderate degree of control. Sodium dodecyl sulfate (SDS) gel electrophoresis, circular dichroism spectroscopy, and time-resolved ultraviolet-visible (UV-vis) spectroscopy revealed that the protein was stable during polymerization, and only underwent minor conformational changes. As Hb and erythrocytes are readily available, environmentally friendly, and nontoxic, their ATRPase activity is a useful tool for synthetic polymer chemistry. Moreover, this novel activity enhances the understanding of Hb's redox chemistry in the presence of organobromine compounds.

Differences in molecular structure in cross-linked polycationic nanoparticles synthesized using ARGET ATRP or UV-initiated polymerization

This work compares material properties of polycationic nanoparticles synthesized using the techniques of UV-initiated polymerization or ARGET ATRP and relates differences in material properties to differences in molecular structure. The nanoparticles are based on the pH-responsive monomer 2-(diethylamino)ethyl methacrylate (DEAEMA) copolymerized with poly(ethylene glycol) methyl ether methacrylate (PEGMA), tert-butyl methacrylate (tBMA), and tetraethylene glycol dimethacrylate (TEGDMA) in a surfactant-stabilized monomer-in-water emulsion to form cross-linked nanoscale hydrogels. ARGET ATRP resulted in a narrower distribution of molecular weight for linear analogs of the polycationic nanoparticles. In addition, ARGET ATRP formulations showed a sharper glass transition than UV-initiated formulations, indicating increased homogeneity. These networks could be used as drug delivery carriers or for other nanogel applications that would benefit from polycationic nanoparticles with high homogeneity.

Preparation and Characterization of Alcogels Based on (Poly Ethylene Glycol Methyl Ether Methacrylate-Acrylic Acid) Copolymers

Alcohol absorbents based on poly ethylene glycol methyl ether methacrylate (PEGMEMA) macromer and acrylic acid (AA) were prepared via solution polymerization using trimethyl propane triacrylate (TMPTA) as crosslinker. Swelling capacity of gels was measured in water, ethanol and methanol. Alcohol absorbency was increased with increasing AA content, which can be related to the ability of an AA segment in formation of H-bonding and dissociation of COOH groups to produce of mobile ions. The alcogels absorb ethanol and methanol up to 14.8 and 17.4 g/g, respectively. TG analysis shows that increasing AA content caused an increase of thermal stability of alcogels.

High performance ultrafiltration membrane composed of PVDF blended with its derivative copolymer PVDF-g-PEGMA

Amphiphilic graft copolymers were fabricated from a poly(vinylidene fluoride) (PVDF) backbone that was grafted with poly(ethylene glycol) methyl ether methacrylate (PEGMA) (PVDF-g-PEGMA) using atom transfer radical polymerization (ATRP) method. An intriguing membrane of periodic pillar-like or sphere structures was formed using PVDF/PVDF-g-PEGMA block copolymer mixtures that were dissolved in suitable solvents. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle measurement, and flux performance tests were conducted to determine the membrane characteristics. The results show that the defect-free high performance ultrafiltration membrane can be fabricated by adding 10wt% or 15wt% PVDF-g-PEGMA to the PVDF backbone material using the phase inversion method. The permeate fluxes of the fabricated membrane with 10wt% and 15wt% PVDF534K-g-PEGMA are 5110 (L/m2hbar) and 5170 (L/m2hbar), respectively, for deionized water under 0.07MPa. The TOC (sodium alginate) removal efficiencies of PVDF membranes with 10wt%, and 15wt% PVDF534K-g-PEGMA are 90.97%, and 87.19%, respectively. Furthermore, the removals of Suwannee River humic acid that contained 2mM CaCl2 and 10mM Ca(OH)2 for the PVDF membrane with 10wt% PVDF534K-g-PEGMA are 72.11% and 77.69%, respectively. This defect-free high-performance membranes show good potential for water treatment applications.

Biofouling-resistance control of expanded poly(tetrafluoroethylene) membrane via atmospheric plasma-induced surface PEGylation

In this work, the research focus is laid on the preparation of biofouling-resistant expanded poly(tetrafluoroethylene) (ePTFE) membranes via a facile process of atmospheric plasma-induced surface PEGylation. After surface coating of poly(ethylene glycol) methyl ether methacrylate (PEGMA), plasma-induced copolymerization was performed by a new atmospheric plasma treatment process over a short period ranging from 0 to 120s. Controllable grafting and growth of PEGylated copolymer segments with treatment time was ascertained by FT-IR, contact angle, surface roughness, and grafting yield analysis. The grafting yield was enhanced with the plasma treatment duration, evidencing a very good process control. The surface roughness increased until a 60s treatment time, before decreasing owed to saturation of surfaces with grafted copolymer and the obtaining of homogeneous PEGylated layer. The water contact angle dropped from 105±1° for the virgin membrane to 9±1° for the PEGylated ePTFE membrane obtained at a 120s plasma treatment, evidencing superhydrophilic surfaces. The PEGylated ePTFE membranes effectively reduced the adsorption of fibrinogen, a sticky protein, up to 18% the limitation of the virgin membrane. Bacterial attachment owed to Gram-positive bacteria (Staphylococcus epidermidis) and Gram-negative bacteria (Escherichia coli) was also effectively inhibited even after a 24h incubation time from a 60s treatment time, corresponding to a grafting yield of 0.10mg/cm2. This work suggests that the anti-baterial ePTFE membranes grafted with PEGylated layer in sufficient surface coverage, high hydration capability, and efficient grafting time via atmospheric plasma treatment present potential for use in membrane bioreactor applications, for which biofouling is a major issue.

Amphiphilic poly(vinyl chloride)‐g‐poly[poly(ethylene glycol) methylether methacrylate] copolymer for the surface hydrophilicity modification of poly(vinylidene fluoride) membrane

AbstractIn this study, a comblike amphiphilic graft copolymer containing poly(vinyl chloride) (PVC) backbones and poly(oxyethylene methacrylate) [poly(ethylene glycol) methylether methacrylate (PEGMA)] side chains was facilely synthesized via an atom transfer radical polymerization method. Secondary chlorines in PVC were used as initial sites to graft a poly[poly(ethylene glycol) methylether methacrylate] [P(PEGMA)] brush. The synthesized PVC‐g‐P(PEGMA) graft copolymer served as an efficient additive for the hydrophilicity modification of the poly(vinylidene fluoride) (PVDF) membrane via a nonsolvent‐induced phase‐inversion technique. A larger pore size, higher porosity, and better connectivity were obtained for the modified PVDF membrane; this facilitated the permeability compared to the corresponding virgin PVDF membrane. In addition, the modified PVDF membrane showed a distinctively enhanced hydrophilicity and antifouling resistance, as suggested by the contact angle measurement and flux of bovine serum albumin solution tests, respectively. Accordingly, the PVC‐g‐P(PEGMA) graft copolymer was demonstrated as a successful additive for the hydrophilicity modification, and this study will likely open up new possibilities for the development of efficient amphiphilic PVC‐based copolymers for the excellent hydrophilicity modification of PVDF membranes. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Effect of shell-crosslinking of micelles on endocytosis and exocytosis: acceleration of exocytosis by crosslinking.

Uptake of drug-loaded micelles by tumour cell lines can be the crucial step in the creation of an efficient drug delivery system. Crosslinking of micelles has increasingly been proposed as a pathway to create stable nanoparticles. So far, little is known how crosslinking can affect the interaction of these nanocarriers with cells. The aim of this study is therefore to investigate the effect of crosslinking on exo- and endocytosis. RAFT (reversible addition fragmentation chain transfer) polymerization has been used to synthesize the block copolymer poly(methyl methacrylate)-block-poly(polyethylene glycol methyl ether methacrylate) PMMA-b-P(PEGMEMA), which was subsequently self-assembled into micelles of 20 nm. For comparison, the micelles were shell-crosslinked by incorporating methacrylic acid into the shell, which was used as a reactive group for crosslinking with 1,8-diaminooctane. The hydrodynamic diameter of the shell-crosslinked micelle was with 25 nm similar to that of the non-crosslinked one. Endocytosis of both micelles was significantly reduced by the presence of NaN3 or at 4 °C suggesting an energy dependent process. The internalization pathways of the block copolymer micelles in OVCAR-3 cells were elucidated using endocytosis inhibitors. Both nanoparticles, micelles and shell-crosslinked micelles, were internalized by caveolae mediated endocytosis while clathrin mediated endocytosis did not play a noticeable role. Shell-crosslinking therefore did not have an effect on endocytosis. However, a considerable difference was found in the exocytosis of both particles. While the micelle was lodged inside the cell for an extended period of time with less than 3% released in two hours, the shell-crosslinked micelle quickly exited the OVCAR-3 cells (25% in two hours). For comparison, a small molecule (Lucifer yellow) was found to be only marginally faster than the crosslinked micelles (40% in 2 h). These results could have implications on the use polymer-drug conjugates or drug carriers where the drug needs to be released before the polymer undergoes exocytosis.

Magnetite Nanoparticle with Positively Charged Surface for Immobilization of Peptide Nucleic Acid and Deoxyribonucleic Acid

We herein report the surface modification of magnetite nanoparticle (MNP) with the (co)polymer of poly(ethylene glycol) methyl ether methacrylate (PEGMA) and/or diethylamino ethyl methacrylate (DEAEMA) via atom transfer radical polymerization (ATRP) for use as anion exchanger solid support for detection of DNA sequence using peptide nucleic acid (PNA) probe. Molar ratio of the PEGMA:DEAEMA (co)polymer was systematically varied to tune the positive charges on the particle surface. Kinetic studies of the (co)polymerizations were investigated via 1HNMR to disclose the relative reactivity of the (co)polymers in the reaction. Zeta potential of the (co)polymer-grafted MNP was analyzed by photo correlation spectroscopy (PCS). Transmission electron microscopy (TEM) and PCS indicated an improvement in the particle dispersibility in water upon quaternization of the DEAEMA entities grafted on the particle surface. From the preliminary results, these (co)polymer-grafted MNPs can be used as a nanosolid support to differentiate between full match and single-base mismatch DNA sequences using an acpcPNA probe. These novel cationic MNPs might be efficiently applicable for use as a magnetically guidable tool for detection of DNA sequences.