Oligo Ethylene Glycol Methyl Ether Research Articles

Application of Redox-Responsive Hydrogels Based on 2,2,6,6-Tetramethyl-1-Piperidinyloxy Methacrylate and Oligo(Ethyleneglycol) Methacrylate in Controlled Release and Catalysis.

Hydrogels have reached momentum due to their potential application in a variety of fields including their ability to deliver active molecules upon application of a specific chemical or physical stimulus and to act as easily recyclable catalysts in a green chemistry approach. In this paper, we demonstrate that the same redox-responsive hydrogels based on polymer networks containing 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) stable nitroxide radicals and oligoethylene glycol methyl ether methacrylate (OEGMA) can be successfully used either for the electrochemically triggered release of aspirin or as catalysts for the oxidation of primary alcohols into aldehydes. For the first application, we take the opportunity of the positive charges present on the oxoammonium groups of oxidized TEMPO to encapsulate negatively charged aspirin molecules. The further electrochemical reduction of oxoammonium groups into nitroxide radicals triggers the release of aspirin molecules. For the second application, our hydrogels are swelled with benzylic alcohol and tert-butyl nitrite as co-catalyst and the temperature is raised to 50 °C to start the oxidation reaction. Interestingly enough, benzaldehyde is not miscible with our hydrogels and phase-separate on top of them allowing the easy recovery of the reaction product and the recyclability of the hydrogel catalyst.

Reversible Stimuli-Dependent Aggregation-Induced Emission from a "Nonfluorescent" Amphiphilic PVDF Graft Copolymer.

A poly(vinylidine fluoride) graft random copolymer of t-butyl aminoethyl methacrylate (tBAEMA) and oligo(ethylene glycol) methyl ether methacrylate (OEGMA, Mn = 300) [PVDF-g-P(tBAEMA-ran-OEGMA), PVBO] is synthesized by atom transfer radical polymerization (ATRP), and PVBO is fractionated to get a highly water-soluble fraction (PVBO-1) showing a reversible on/off fluorescence behavior with gradual increase and decrease in pH, respectively, achieving a maximum quantum yield of 0.18 at pH = 12. PVBO-1 dissolved in water shows large multimicellar aggregates (MMcA), but at pH 12, crumbling of larger aggregates to much smaller micelles occurs, forming nonconjugated polymer dots (NCPDs), as supported by transmission electron microscopy and dynamic light scattering study. The reversible fluorescence on/off behavior also occurs with the decrease and increase of temperature. Theoretical study indicates that, at high pH, most of the amino groups become neutral and exhibit a strong tendency to form aggregates from crowding of a large number of carbonyl and amine groups, minimizing the HOMO-LUMO gap, showing an absorption peak at the visible region, and generating aggregation-induced emission.

Nano-Assemblies from Amphiphilic PnBA-b-POEGA Copolymers as Drug Nanocarriers.

The focus of this study is the development of highly stable losartan potassium (LSR) polymeric nanocarriers. Two novel amphiphilic poly(n-butyl acrylate)-block-poly(oligo(ethylene glycol) methyl ether acrylate) (PnBA-b-POEGA) copolymers with different molecular weight (Mw) of PnBA are synthesized via reversible addition fragmentation chain transfer (RAFT) polymerization, followed by the encapsulation of LSR into both PnBA-b-POEGA micelles. Based on dynamic light scattering (DLS), the PnBA30-b-POEGA70 and PnBA27-b-POEGA73 (where the subscripts denote wt.% composition of the components) copolymers formed micelles of 10 nm and 24 nm in water. The LSR-loaded PnBA-b-POEGA nanocarriers presented increased size and greater mass nanostructures compared to empty micelles, implying the successful loading of LSR into the inner hydrophobic domains. A thorough NMR (nuclear magnetic resonance) characterization of the LSR-loaded PnBA-b-POEGA nanocarriers was conducted. Strong intermolecular interactions between the biphenyl ring and the butyl chain of LSR with the methylene signals of PnBA were evidenced by 2D-NOESY experiments. The highest hydrophobicity of the PnBA27-b-POEGA73 micelles contributed to an efficient encapsulation of LSR into the micelles exhibiting a greater value of %EE compared to PnBA30-b-POEGA70 + 50% LSR nanocarriers. Ultrasound release profiles of LSR signified that a great amount of the encapsulated LSR is strongly attached to both PnBA30-b-POEGA70 and PnBA27-b-POEGA73 micelles.

ABC Triblock Copolymers Antibacterial Materials Consisting of Fluoropolymer and Polyethylene Glycol Antifouling Block and Quaternary Ammonium Salt Sterilization Block.

Due to their various applications in human healthcare and industrial fields, engineering surfaces with antiadhesion and antibacteria properties is still a challenging task. In this work, the fluoropolymer with low surface energy and poly(poly(ethylene glycol) methyl ether methacrylate) (PEGMA) with electrostatic repulsion and interfacial hydration was chosen as a common antiadhesion block and quaternary ammonium salt with bactericide properties as a sterilization block. The triblock copolymers of poly(2-(dimethylamino)ethyl methacrylate)-b-poly(poly(oligo ethylene glycol) methyl ether methacrylate)-b-poly(dodecafluoroheptyl methacrylate) (PDMAEMA-b-PEGMA-b-PDFHMA) were synthesized by the reversible addition-fragmentation chain transfer (RAFT) polymerization method. Then, the synthesized triblock copolymers were quaternized to obtain the antibacterial materials (QPDMAEMA-b-PEGMA-b-PDFHMA). It has been found that the QPDMAEMA-b-PEGMA-b-PDFHMA triblock copolymer coating has excellent antiadhesion and antibacterial properties against S. aureus and E. coli. The synergistic effects of fluoropolymer and PEGMA can enhance the antifouling properties of the coating. At the same time, it has a good antifouling effect on platelets and red blood cells. In addition, the triblock copolymer coating has long-term stability in high ionic strength solution of PBS in dynamic conditions. These kind of materials with antifouling and antibacterial properties may have potential applications on the surface of various public utilities and medical equipment.

Hydration in thermo-responsive oligoether methacrylate hydrogels studied by FT-IR spectroscopy

Hydration in thermo-responsive polymer hydrogels, such us poly(oligo(ethylene glycol) methyl ether methacrylates) (POEGMAs) is a key factor in understanding their thermo-responsivity. The hydration of POEGMAs with different length of side groups was comprehensively studied for the first time. The comparative studies have shown that hydration of different hydrophilic centres in various POEGMAs is similar and independent of oligoether chain length. Only some quantitative differences in bound water structure, especially at the first stage of hydration have been found. However, the crystallinity (if it occurs) significantly impacts on the hydration process. Finally, the water structure is the closer to the bulk water structure in the fully swollen PMEO2MA hydrogel than in other POEGMA systems with longer oligoether side groups.

Amphiphilic Perfluoropolyether Copolymers for the Effective Removal of Polyfluoroalkyl Substances from Aqueous Environments

Effective removal of per- and polyfluoroalkyl substances (PFAS) from the environment has become a major focus of a number of research groups due to their high stability and persistence in the environment. In this study, we report a fundamental study of the removal of one of the most extensively produced PFAS, perfluorooctanoic acid (PFOA), using amphiphilic perfluoropolyether (PFPE)-containing block copolymers as effective sorbents. The results demonstrate interactions between PFOA and the PFPE blocks and that the extent of sorption is higher for the block copolymer with the shorter poly(oligo(ethylene glycol)methyl ether acrylate) segments. High selectivity of sorption was further confirmed by the addition of 10% (v/v) fetal bovine serum to phosphate-buffered saline. The presence of dissolved proteins and other biomolecules did not interfere with the removal of PFOA from solution. Overall, the results provide important design parameters and a potential platform for preparing efficient sorbents for treating PFAS samples at environmentally relevant concentrations.

An intracellular enzyme-responsive polymeric prodrug with synergistic effect of chemotherapy and two-photon photodynamic therapy

The combination of chemotherapy/photodynamic therapy (PDT) has shown synergistically enhanced anticancer efficacies. However, precise delivery of therapeutic agents to the site-of-action and activation of PDT in deep tissues are still challenging. Herein, a poly [oligo (ethylene glycol) methyl ether methacrylate] (polyOEGMA)-functionalized dendritic polymer-paclitaxel prodrug with a hydrophobic core was designed and prepared to encapsulate pyropheophorbide a (PPa) and an imidazole derivative, two-photon (TP) absorption compound T1. As a short peptide GFLG that was sensitive to intracellular cathepsin B was inserted into the branches of the dendritic polymer and also used as a linker to conjugate paclitaxel (PTX) to the polymer, the nanosystem released PTX in a tumor microenvironment-responsive manner and was partially degraded. The TP compound T1 had a high energy-transfer efficiency and displayed an enhanced two-photon photodynamic therapy (TP-PDT) effect, thus resulting in an increased anticancer efficacy, which was confirmed with the results of in situ TP-PDT anti-tumor efficiencies and apoptosis assays. The synergistic effect on inhibition of tumor growth in the 4T1 xenograft mice was achieved due to the combination of chemotherapy (PTX) and PDT (PPa or TP-PDT compound T1). Importantly, the chemo/TP-PDT combined system achieved a much higher tumor growth inhibition (TGI, 67.23%) in the tissue surrounded with thick swine muscle as compared to the group treated with PTX and PPa (48.92%). The prodrug-based nanosystem loaded with PTX and TP-PDT agents could overcome the challenge of conventional one-photon PDT with a short penetration depth into tissues to achieve a notably enhanced synergistic anticancer efficacy.

Poly(oligo(ethylene glycol) methyl ether methacrylate) Capped pH-Responsive Poly(2-(diethylamino)ethyl methacrylate) Brushes Grafted on Mesoporous Silica Nanoparticles as Nanocarrier.

In this paper, a new pH-responsive nanosystem based on mesoporous silica nanoparticles (MSNs) was developed for cancer therapy. Poly(2-(diethylamino) ethyl methacrylate) (PDEAEMA) was grafted on their outer surface and acts as a gatekeeper, followed by subsequent modification of the polymer by cysteine (MSN-PDEAEMA-Cys) and poly(oligo(ethylene glycol) methyl ether methacrylate) (MSN-PDEAEMA-Cys-POEGMEMA). The physicochemical properties of these nanocarriers were characterized using scanning and transmission electron microscopies (SEM and TEM), Fourier-transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and dynamic light scattering (DLS). The synthesized nanoparticles were well-dispersed with a diameter of ca. 200 nm. The obtained XPS results confirm the successful modification of MSN-PDEAEMA with Cys and POEGMEMA by increasing the peak intensity of C–O and C=O groups at 286.5 and 288.5 eV, respectively. An anti-cancer drug, doxorubicin (DOX), was encapsulated into the fabricated nanoplatform. The DOX release amount at physiological pH of 7.4 was limited (10%), while an accumulation drug release of ca. 35% was accomplished after 30 h in acidic media. The MTT cell line was used to assess the cytotoxicity of the unloaded and DOX-loaded fabricated nanoplatforms. Upon loading of DOX on these nanomaterials, they showed significant toxicity to human liver cancer cells. These results suggest that the prepared nano-structured materials showed good biocompatibility as well, and they can serve as nanocarriers for the delivery of anti-cancer drugs.

Synthesis of bio‐based poly(methacrylates) using SG1‐containing amphiphilic macroinitiators by nitroxide mediated miniemulsion polymerization

AbstractSG1‐based amphiphilic macroinitiators were synthesized from oligoethylene glycol methyl ether methacrylate and 10 mol% acrylonitrile or styrene (as the controlling comonomer) to conduct the nitroxide mediated polymerization of bio‐based methacrylic monomers (isobornyl methacrylate (IBOMA) and C13 alkyl methacrylate (C13MA)) in miniemulsion. The effect of the addition of surfactant (DOWFAX 8390), co‐stabilizer (n‐hexadecane) and different reaction temperatures (80, 90 and 100°C) on polymerization kinetics was studied. We found that the NMP of IBOMA/C13MA using amphiphilic macroalkoxyamines were most effective during miniemulsion polymerization (linear trend of Mn versus conversion and high latex stability) in presence of 2 wt% surfactant and 0.8 wt% co‐stabilizer (relative to monomer) at 90°C. The effect of surfactant, co‐stabilizer and temperature on particle size during the polymerization was studied and suggested a decrease in initial particle size with the addition of surfactant and co‐stabilizer. Finally, the thermal properties of IBOMA/C13MA polymers, prepared by amphiphilic macroinitiators, were examined thoroughly, indicating a Tg in the range of −44°C < Tg < 109°C.

Multifaceted pH and Temperature Induced Self‐Assembly of P(DMAEMA‐co‐LMA)‐b‐POEGMA Terpolymers and Their Cationic Analogues in Aqueous Media

AbstractThis work focuses on the synthesis of novel amphiphilic block terpolymers of the type poly[(2‐(N,N‐dimethylamino) ethyl methacrylate)‐co‐(lauryl methacrylate)]‐b‐poly[(oligo ethylene glycol) methyl ether methacrylate] (P(DMAEMA‐co‐LMA)‐b‐POEGMA)) by reversible addition‐fragmentation chain transfer polymerization. The cationic amphiphilic polyelectrolyte analogs P(QDMAEMA‐co‐LMA)‐b‐POEGMA are obtained through quantitative quaternization of the DMAEMA segments. Molecular characterization by size exclusion chromatography, nuclear magnetic resonance, and Fourier Transform Infrared spectroscopies indicates the successful synthesis of these novel series of block terpolymers. The amine forms of the block copolymers respond to pH and temperature changes in aqueous solutions by forming unimolecular or multichain nanoaggregates of varying size, micropolarity, and internal structure, as indicated by light scattering and fluorescence spectroscopy techniques. At neutral and basic pH, the existence of micellar like nanoassemblies is observed in the solutions of P(DMAEMA‐co‐LMA)‐b‐POEGMA terpolymers, while aggregation into micellar‐like clusters take place at temperature values above room temperature due to the presence of the hydrophobic LMA segments. Unexpectedly, the cationic polyelectrolytes P(QDMAEMA‐co‐LMA)‐b‐POEGMA counterparts show temperature responsiveness as a consequence of the amphiphilicity of the polymeric system.

An acid-triggered porphyrin-based block copolymer for enhanced photodynamic antibacterial efficacy

Bacterial infection, especially multidrug-resistant (MDR) bacterial infection has threatened public health drastically. Here, we fabricate an “acid-triggered” nanoplatform for enhanced photodynamic antibacterial activity by reducing the aggregation of photosensitizers (PSs) in bacterial acidic microenvironment. Specifically, a functional amphiphilic block copolymer was first synthesized by using a pH-sensitive monomer, 2-(diisopropylamino) ethyl methacrylate (DPA) and porphyrin-based methacrylate (TPPC6MA) with poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) as the macromolecular chain transfer agent, and POEGMA-b-[PDPA-co-PTPPC6MA] block copolymer was further self-assembled into spherical nanoparticles (PDPA-TPP). PDPA-TPP nanoparticles possess an effective electrostatic adherence to negatively charged bacterial cell membrane, since they could rapidly achieve positive charge in acidic bacterial media. Meanwhile, the acid-triggered dissociation of PDPA-TPP nanoparticles could reduce the aggregation caused quenching (ACQ) of the photosensitizers, leading to around 5 folds increase of the singlet oxygen (1O2) quantum yield. In vitro results demonstrated that the “acid-triggered” PDPA-TPP nanoparticles could kill most of MDR S. aureus (Gram-positive) and MDR E. coli (Gram-negative) by enhanced photodynamic therapy, and they could resist wound infection and accelerate wound healing effectively in vivo. Furthermore, PDPA-TPP nanoparticles could well disperse the biofilm and almost kill all the biofilm-containing bacteria. Thus, by making use of the bacterial acidic microenvironment, this “acid-triggered” nanoplatform in situ will open a new path to solve the aggregation of photosensitizers for combating broad-spectrum drug-resistant bacterial infection.

Phase transition characterization of poly(oligo(ethylene glycol)methyl ether methacrylate) brushes using the quartz crystal microbalance with dissipation.

Heterogeneous non-linear poly(ethylene glycol) analogs, like poly(oligo(ethylene glycol)methyl ether methacrylate) (POEGMA), are of particular interest in the fabrication of smart biocompatible coatings as they undergo a reversible macromolecular rearrangement in response to external heat stimuli. The phase transition dynamics of POEGMA coatings in response to external temperature stimuli have been poorly investigated. The quartz crystal microbalance with dissipation (QCM-D) can be used to investigate the phase transition of these functional coatings as polymer brushes in a dynamic and noninvasive in situ measurement. POEGMA brushes with different thickness are synthesized from the surface of a QCM-D sensor following a living radical polymerization technique by varying the monomer molecular weight. Investigations on the thermoresponsive collapse and swelling of POEGMA brushes grafted from the surface of a QCM-D sensor reveal the reversible phase transition nature of these coatings. Furthermore, the potential of these smart coatings in the field of biotechnology was explored by investigating the absorption and desorption of a model drug. A pulsatile drug release profile triggered by an increase in temperature is observed from POEGMA brushes. POEGMA brushes have the potential to be utilized as polymer coatings for controlled and programable drug release.

Abnormal fast dehydration and rehydration of light- and thermo-dual-responsive copolymer films triggered by UV radiation.

Abnormal fast dehydration and rehydration of light- and thermo-dual-responsive copolymer films of poly(oligo(ethylene glycol) methyl ether methacrylate-co-6-(4-phenylazophenoxy)hexyl acrylate), abbreviated as P(OEGMA300-co-PAHA), are triggered by UV radiation. Both rapid kinetic processes are probed by in situ neutron reflectivity (NR). The transition temperatures (TTs) of P(OEGMA300-co-PAHA) are 53.0 (ambient conditions) and 52.5 °C (UV radiation, λ = 365 nm). Thin P(OEGMA300-co-PAHA) films show a random distribution of OEGMA300 and PAHA segments. They swell in a D2O vapor atmosphere at 23 °C (below TT) to a swelling ratio d/das-prep of 1.61 ± 0.01 and exhibit a D2O volume fraction φ(D2O) of 39.3 ± 0.5%. After being exposed to UV radiation for only 60 s, d/das-prep and φ(D2O) significantly decrease to 1.00 ± 0.01 and 13.4 ± 0.5%, respectively. Although the UV-induced trans-cis isomerization of the azobenzene in PAHA induces increased hydrophilicity, the configuration change causes a breaking of the intermolecular hydrogen bonds between OEGMA300 and D2O molecules and unexpected film shrinkage. As compared to thermal stimulus-induced dehydration, the present dehydration rate is 100 times faster. Removal of the UV radiation causes immediate rehydration. After 200 s, d/das-prep and φ(D2O) recover to their hydrated states, which is also 30 times faster than the initial hydration. At 60 °C (above TT), thin P(OEGMA300-co-PAHA) films switch to their collapsed state and are insensitive to UV radiation. Thus, the UV-induced fast dehydration and rehydration depend on the existence of hydrogen bonds.

Pyridine-2,6-dicarboxaldehyde-Enabled N-Terminal In Situ Growth of Polymer-Interferon α Conjugates with Significantly Improved Pharmacokinetics and In Vivo Bioactivity.

Polymer-protein conjugates are a class of biohybrids with unique properties that are highly useful in biomedicine ranging from protein therapeutics to biomedical imaging; however, it remains a considerable challenge to conjugate polymers to proteins in a site-specific, mild, and efficient way to form polymer-protein conjugates with uniform structures and properties and optimal functions. Herein we report pyridine-2,6-dicarboxaldehyde (PDA)-enabled N-terminal modification of proteins with polymerization initiators for in situ growth of poly(oligo(ethylene glycol)methyl ether methacrylate) (POEGMA) conjugates uniquely at the N-termini of a range of natural and recombinant proteins in a mild and efficient fashion. The formed POEGMA-protein conjugates showed highly retained in vitro bioactivity as compared with free proteins. Notably, the in vitro bioactivity of a POEGMA-interferon α (IFN) conjugate synthesized by this new chemistry is 8.1-fold higher than that of PEGASYS that is a commercially available and Food and Drug Administration (FDA) approved PEGylated IFN. The circulation half-life of the conjugate is similar to that of PEGASYS but is 46.2 times longer than that of free IFN. Consequently, the conjugate exhibits considerably improved antiviral bioactivity over free IFN and even PEGASYS in a mouse model. These results indicate that the PDA-enabled N-terminal grafting-from method is applicable to a number of proteins whose active sites are far away from the N-terminus for the synthesis of N-terminal polymer-protein conjugates with high yield, well-retained activity, and considerably improved pharmacology for biomedical applications.

Physicochemical Properties and Biological Performance of Polymethacrylate Based Gene Delivery Vector Systems: Influence of Amino Functionalities.

Physicochemical characteristics and biological performance of polyplexes based on two identical copolymers bearing tertiary amino or quaternary ammonium groups are evaluated and compared. Poly(2-(dimethylamino)ethyl methacrylate)-b-poly(oligo(ethylene glycol) methyl ether methacrylate) block copolymer (PDMAEMA-b-POEGMA) is synthesized by reversible addition fragmentation chain transfer polymerization. The tertiary amines of PDMAEMA are converted to quaternary ammonium groups by quaternization with methyl iodide. The two copolymers spontaneously formed well-defined polyplexes with DNA. The size, zeta potential, molar mass, aggregation number, and morphology of the polyplex particles are determined. The parent PDMAEMA-b-POEGMA exhibits larger buffering capacity, whereas the corresponding quaternized copolymer (QPDMAEMA-b-POEGMA) displays stronger binding affinity to DNA, yielding invariably larger in size and molar mass particles bearing greater number of DNA molecules per particle. Experiments revealed that QPDMAEMA-b-POEGMA is more effective in transfecting pEGFP-N1 than the parent copolymer, attributed to the larger size, molar mass, and DNA cargo, as well as to the effective cellular traffic, which dominated over the enhanced ability for endo-lysosomal escape of PDMAEMA-b-POEGMA.

Effect of Molecular Architecture and Composition on the Aggregation Pathways of POEGMA Random Copolymers in Water.

Understanding of the temperature-induced phase transition of poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA) random copolymers with varied composition remains largely incomplete. Upon heating they can form either macroscopically phase-separated aggregates or micelles. We examined the effect of polymer architecture by rationally designing and synthesizing various POEGMA copolymer structures via atom transfer radical polymerization using OEGMA monomers of different EO lengths. Micelle formation occurred for copolymers with a small fraction of long side chains counterbalanced by an appropriate number of short side chains, while macroscopic phase separation occurred for other copolymer compositions. In some copolymer compositions and architectures, micelle formation followed by macroscopic phase separation occurred, and the temperature of these phase transitions could be tailored accordingly. This new strategy allows the control over the microstructure and specific transition temperatures enabling, for instance, the preparation of nanocarriers for encapsulating hydrophobic compounds.

Phase transitions of poly(oligo(ethylene glycol) methyl ether methacrylate)-water systems

The phase diagrams for poly (oligo (ethylene glycol) methyl ether methacrylate) (POEGMA) hydrogels with varying side chain lengths over broad temperature and composition ranges are shown for the first time. It is also shown that the ability of water to crystallize is strictly correlated with the occurrence of a volume phase transition in hydrogels, as both phenomena require the continuous water pathways in the system. A discontinuity in the water phase appears above wp = 0.83 for PMEO2MA and wp = 0.56 for other POEGMAs. In contrast to PMEO2MA, POEGMA hydrogels with longer oligoether chains are characterized by two distinct regimes for the glass transition as a function of polymer content. It was also confirmed that crystallization of the polymer network can be observed for POEGMA networks with suitably long oligoether chain lengths, namely, n ≥ 7. Moreover, the range of the polymer crystalline phase occurrence was found to increase with the length of the oligoether chain.

Trisulfide-Bearing PEG Brush Polymers Donate Hydrogen Sulfide and Ameliorate Cellular Oxidative Stress.

A potential approach to combat cellular dysfunction is to manipulate cell communication and signaling pathways to restore physiological functions while protecting unaffected cells. For instance, delivering the signaling molecule H2S to certain cells has been shown to restore cell viability and re-normalize cell behavior. We have previously demonstrated the ability to incorporate a trisulfide-based H2S-donating moiety into linear polymers with good in vitro releasing profiles and demonstrated their potential for ameliorating oxidative stress. Herein, we report two novel series of brush polymers decorated with higher numbers of H2S-releasing segments. These materials contain two trisulfide-based monomers co-polymerized with oligo(ethylene glycol methyl ether methacrylate) via reversible addition-fragmentation chain-transfer polymerization. The macromolecules were characterized to have a range of trisulfide densities with similar, well-defined molecular weight distribution, good H2S-releasing profiles, and high cellular tolerance. Using an amperometric technique, the H2S liberated and total sulfide release were found to depend on concentrations and chemical nature of triggering molecules (glutathione and cysteine) and, importantly, the position of reactive groups within the brush structure. Notably, when introduced to cells at well-tolerated doses, two macromolecular donors which have the same proportion as of the H2S-donating monomer (30%) but differ in releasing moiety location show similar cellular H2S-releasing kinetics. These donors can restore reactive oxygen species levels to baseline values, when polymer pretreated cells are exposed to exogenous oxidants (H2O2). Our work opens up a new aspect in preparing H2S macromolecule donors and their application to arresting cellular oxidative cascades.

Synthesis of Block Copolymer Brush by RAFT and Click Chemistry and Its Self-Assembly as a Thin Film.

A well-defined block copolymer brush poly(glycidyl methacrylate)-graft-(poly(methyl methacrylate)-block- poly(oligo(ethylene glycol) methyl ether methacrylate)) (PGMA-g-(PMMA-b-POEGMA)) is synthesized via grafting from an approach based on a combination of click chemistry and reversible addition-fragmentation chain transfer (RAFT) polymerization. The resulting block copolymer brushes were characterized by 1H-NMR and size exclusion chromatography (SEC). The self-assembly of the block copolymer brush was then investigated under selective solvent conditions in three systems: THF/water, THF/CH3OH, and DMSO/CHCl3. PGMA-g-(PMMA-b-POEGMA) was found to self-assemble into spherical micelle structures as analyzed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The average size of the particles was much smaller in THF/CH3OH and DMSO/CHCl3 as compared with the THF/water system. Thin film of block copolymer brushes with tunable surface properties was then prepared by the spin-coating technique. The thickness of the thin film was confirmed by scanning electron microscopy (SEM). Atom force microscopy (AFM) analysis revealed a spherical morphology when the block copolymer brush was treated with poor solvents for the backbone and hydrophobic side chains. The contact angle measurements were used to confirm the surface rearrangements of the block copolymer brushes.

Amphiphilic QP(DMAEMA-co-LMA)-b-POEGMA Random-Block Terpolymers as Nanocarriers for Insulin.

We report on the utilization of the amphiphilic poly[quaternized (2-(N,N-dimethylamino) ethyl methacrylate)]-co-(lauryl methacrylate))-b-poly[(oligo ethylene glycol) methyl ether methacrylate] QP(DMAEMA-co-LMA)-b-POEGMA cationic diblock terpolymer aggregates as nanocarriers for insulin delivery applications. QP(DMAEMA-co-LMA)-b-POEGMA random diblock terpolymer is derived from the chemical modification of the precursor amino diblock copolymer via quaternization, producing permanent positive charges on the macromolecular chain. The QP(DMAEMA-co-LMA)-b-POEGMA diblock terpolymer as well as its amino precursor investigated self-assemble in aqueous media, forming aggregates. In vitro cytotoxicity and in vivo biocompatibility studies on QP(DMAEMA-co-LMA)-b-POEGMA and its amino precursor aggregates, showed good cytocompatibility and biocompatibility. QP(DMAEMA-co-LMA)-b-POEGMA aggregates were chosen to be complexed with insulin due to their self-assembly features and the permanent positive charge in each amino group. QP(DMAEMA-co-LMA)-b-POEGMA aggregates were complexed with insulin through electrostatic interactions. Light scattering techniques were used in order to study the ability of the polymer aggregates to complex with insulin, to determine critical physicochemical parameters such as size, mass, and surface charge of the stable complexes and study the effect of salt addition on their properties. The results showed that in both cases, the complexation process was successful and as the insulin concentration increases, nanosized complexes of different physicochemical characteristics (mass, size, surface charge) and spherical morphology are formed. UV-Vis and fluorescence spectroscopy studies showed that no conformational changes of insulin occurred after the complexation.