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Magnetite nanoparticles (MNPs) grafted with poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) and their use as anionic nano-adsorbents for positively charged antibody were herein presented. PAMPS grafted on MNP surface provided good water dispersibility and high negatively charged surface for electrostatic adsorption with positively charged entities, and MNPs provided a good magnetic responsiveness to facilitate the separation process. From transmission electron microscopy results, the size of the nanoclusters ranged between 50 and 200 nm in diameter with ca. 50–150 particles/cluster. Degree of the negative charge of PAMPS-grafted MNPs increased when increasing pH of the dispersion, indicating the pH-responsive properties of the MNPs. These MNPs were successfully used as nano-adsorbents for adsorption with anti-rabbit IgG through ionic interaction between negative charge of PAMPS-grafted MNP and positive charge of the antibody. In addition, the MNPs also provided the reusable ability by adsorption-desorption cycling process with higher than 80% adsorption ability after five consecutive reusing cycles. These hybrid materials should be alternative nano-adsorbents for other positively charged entities with high adsorption efficiency and reusable supports in magnetic separation applications. [ABSTRACT FROM AUTHOR]

This novel nano-adsorbent offers high selectivity and rapid screening of Hg2+ through visual detection. The process involved coating the magnetic nanoparticle (MNP) with alginate, followed by immobilization of a DNA aptamer specific to Hg2+, resulting in the formation of Apt@Alg@MNP. It was utilized as a nano-adsorbent for rapid screening tests to qualitatively detect Hg2+ on the particles by observing the color change in the Hg2+-adsorbed Apt@Alg@MNP dispersion. The nano-adsorbent exhibited high specificity toward Hg2+ and demonstrated strong anti-interference capability. It was successfully employed as a nano-adsorbent for the determination of Hg2+ in various real water samples. [ABSTRACT FROM AUTHOR]

Glycidyl-functionalized poly( N -isopropylacrylamide) (PNIPAAm), synthesized via a reversible addition-fragmentation transfer polymerization (RAFT), was used for controlling degree of nanoclustering of magnetite nanoparticle (MNP). The polymer was grafted onto MNP via the ring-opening reaction between glycidyl groups at the PNIPAAm chain terminal and amino groups on the MNP surface to obtain thermo-responsive MNP nanocluster. Hydrodynamic size (D h ) and colloidal stability of the nanocluster, corresponding to the degree of nanoclustering reaction, can be regulated either by adjusting the ratio of MNP to the polymer in the reaction or by introducing glycidyl groups to the polymers. The size of the nanocluster ranged between 20 and 150 nm in diameter with about 10–120 particles/cluster. Thermogravimetric analysis (TGA) and vibrating sample magnetometry (VSM) were used to confirm the presence of the polymer in the nanocluster. A study showing indomethacin controlled release of these MNP nanoclusters was also performed. This stable nanocluster with magnetically guidable properties might be potentially used for entrapment of other bio-entities or therapeutic drugs with temperature-responsive properties for controlled release applications. [ABSTRACT FROM AUTHOR]

Multi-responsive composite microspheres were synthesized via an in situ free radical polymerization of thermo-responsive poly( N -isopropylacrylamide) (poly(NIPAAm)) in the presence of carboxymethylchitosan (CMC) and magnetite nanoparticles (MNPs) followed by glutaraldehyde crosslinking. Formulation conditions of the composite microspheres were tuned such that spherical microspheres with narrow size distributions were obtained (30.0 ± 1.0 μm in diameter). They responded well to an applied magnetic field and showed water swelling responses to the change in solution pH and temperature. The release of an entrapped indomethacin model drug was accelerated when the solution temperature was above its lower critical solution temperature (LCST) (50 °C) or when the solution pH was in basic conditions (pH 11). These responsive properties can be used as triggering mechanisms for releases of the entrapped drugs from the microspheres, indicating their great potentials for use in controlled release applications. [ABSTRACT FROM AUTHOR]

This work presented the synthesis of magnetite nanoparticle (Fe3O4) coated with carboxymethyl chitosan (CMC)-based polymers with/without amino-rich poly(2-(diethyl amino)ethyl methacrylate (PDEAEMA) for the coordination with Pd and its use as a reusable catalyst for the reduction of 4-nitrophenol (4NP) and methylene blue (MB). The amino and hydroxy groups in CMC provided good water dispersibility and served as good ligands for coordination with Pd, while the abundant amino groups in PDEAEMA increased the immobilizing stability of Pd in the nanocomposite. It was found that the average diameter of Fe3O4 was 11.73 ± 2.12 nm in diameter and those of Pd was 5.91 ± 1.07 nm with the Pd contents of 0.06–7.62 wt%. The catalyst without PDEAEMA exhibited high catalytic activity for the reduction of both 4NP and MB than those having PDEAEMA. Interestingly, the catalyst containing PDEAEMA showed more recycling durability for the 4NP reduction than the other and these corresponded well to the Pd leaching results. [ABSTRACT FROM AUTHOR]

Magnetite nanoparticles coated with quaternized poly(diethylamino)ethyl methacrylate (PDEAEMA) (PQDEA@MNP) and functionalized with bisphenol A (BPA)-specific peptide aptamer (CKSLENSYC) were synthesized and used as nano-adsorbents for selective adsorption with BPA. The polymer coated on the particles provided their good stability and dispersibility in water, and the aptamer provided selective adsorption with BPA targets. Fourier transformed infrared spectrophotometry (FTIR), thermogravimetric analysis (TGA) and vibrating sample magnetometry (VSM) techniques confirmed the presence of the polymer on the particle surface. From transmission electron microscopy (TEM) study, the particle size was ca.6 - 10 nm in diameter with some nanoclustering (30 - 60 nm in diameter of the nanoclusters). The selective adsorption of BPA on the particles was predominant over the non-specific adsorption when performed in PBS buffer (pH 10) in the presence of NaCl and tween-20. The nano-adsorbents had a good linearity range for the detection of BPA between 0.04 and 0.20 ppm with limit of detection (LOD) of 0.0145 ppm. They retained good BPA adsorption efficiency even when other interfering molecules were present. This simple measurement with the use of these nano-adsorbents without molecular labelling might be promising solid supports for use in various applications with good tolerance towards interfering molecules. [ABSTRACT FROM AUTHOR]

Abstract: Poly(acrylic acid) (poly(AA))-grafted magnetite nanoparticles (MNPs) prepared via surface-initiated atom transfer radical polymerization (ATRP) of t-butyl acrylate, followed by acid-catalyzed deprotection of t–butyl groups, is herein presented. In addition to serve as both steric and electrostatic stabilizers, poly(AA) grafted on MNP surface also served as a platform for conjugating folic acid, a cancer cell targeting agent. Fourier transform infrared spectroscopy (FTIR) was used to monitor the reaction progress in each step of the syntheses. The particle size was 8 nm in diameter without significant aggregation during the preparation process. Photocorrelation spectroscopy (PCS) indicated that, as increasing pH of the dispersions, their hydrodynamic diameter was decreased and negatively charge surface was obtained. According to thermogravimetric analysis (TGA), up to 14 wt% of folic acid (about 400 molecules of folic acid per particle) was bound to the surface-modified MNPs. This novel nanocomplex is hypothetically viable to efficiently graft other affinity molecules on their surfaces and thus might be suitable for use as an efficient drug delivery vehicle particularly for cancer treatment. [Copyright &y& Elsevier]

Abstract: We are herein reporting a synthesis of indomethacin-loaded bilayer-surface magnetite nanoparticles and their releasing behavior. The particles were first stabilized with oleic acid as a primary surfactant, followed by poly(ethylene glycol) methyl ether-poly(ɛ-caprolactone) (mPEG–PCL) amphiphilic block copolymer as a secondary surfactant to form nanoparticles with hydrophobic inner shell and hydrophilic corona. mPEG–PCL copolymers with systematically varied molecular weights of each block (2000–2000, 2000–10,000, 5000–5000 and 5000–10,000g/mol, respectively) were synthesized via a ring-opening polymerization of ɛ-caprolactone using mPEG as a macroinitiator. The particles were 9nm in diameter and exhibited superparamagnetic behavior at room temperature with saturation magnetization (M s) about 35emu/g magnetite. Percent of magnetite and the copolymers in the complexes were determined via thermogravimetric analysis (TGA). The effect of mPEG and PCL block lengths in the copolymer–magnetite complex on the properties of the particles, e.g. particle size, magnetic properties, stability in water, drug entrapping and loading efficiency and its releasing behavior were investigated. This novel magnetic nanocomplex might be suitable for use as an efficient drug delivery vehicle with tunable drug-released properties. [Copyright &y& Elsevier]

Abstract: Poly(ethylene glycol)–polydimethylsiloxane (PEG–PDMS) block copolymers were prepared via a condensation reaction between PEG diacid and PDMS diol. PEG diacid was synthesized from the reaction between hydroxy-terminated PEG and succinic anhydride. PDMS diol was prepared from the ring-opening polymerization of octamethylcyclotetrasiloxane (D4) followed by hydrosilylation with allyl alcohol. The copolymers were incorporated into chitosan in order that good water swellability and wettability of chitosan were retained due to hydrophilic PEG blocks, whereas PDMS block in the copolymers functioned as a toughening modifier. Percent crosslinking of 66–84 was observed once 5–10wt% of the copolymers was incorporated. As compared to the unmodified sample, the copolymer-containing chitosan exhibited the decreases in both water contact angles and the rate of water vapor permeability. The studies on tensile properties indicated that incorporation of copolymers into chitosan improved the flexibility of the films. [Copyright &y& Elsevier]

Abstract: Preparation and properties of polydimethylsiloxane (PDMS)-modified chitosan are discussed herein. A series of PDMS with systematically varied molecular weights were first prepared via acid-catalyzed ring opening polymerization of octamethylcyclotetrasiloxane (D4) to obtain PDMS prepolymers. They were subsequently functionalized with allyl glycidyl ether to obtain epoxy functional groups at PDMS terminals. Their chemical structures and molecular weights were characterized using1H NMR,13C NMR and FTIR, and thermal properties were determined by DSC. The reaction of the epoxidized PDMS and chitosan was carried out in an acidic aqueous solution. Increasing the molecular weights of PDMS and/or its concentrations improved flexibility and water swellability due to the formation of PDMS microphase. Water contact angle and water vapor permeability measurements indicated that incorporation of the PDMS enhanced its hydrophobicity as compared to the unmodified one. [Copyright &y& Elsevier]

Abstract: Synthesis of poly(ethylene glycol)-polydimethylsiloxane amphiphilic block copolymers is discussed herein. Siloxane prepolymer was first prepared via acid-catalyzed ring-opening polymerization of octamethylcyclotetrasiloxane (D4) to form polydimethylsiloxane (PDMS) prepolymers. It was subsequently functionalized with hydroxy functional groups at both terminals. The hydroxy-terminated PDMS can readily react with acid-terminated poly(ethylene glycol) (PEG diacid) to give PEG–PDMS block copolymers without using any solvent. The PEG diacid was prepared from hydroxy-terminated PEG through the ring-opening reaction of succinic anhydride. Their chemical structures and molecular weights were characterized using 1H NMR, FTIR and GPC, and thermal properties were determined by DSC. The PEG–PDMS copolymer was incorporated into chitosan in order that PDMS provided surface modification and PEG provided good water swelling properties to chitosan. Critical surface energy and swelling behavior of the modified chitosan as a function of the copolymer compositions and contents were investigated. [Copyright &y& Elsevier]

Abstract: Synthesis of the statistical epoxidized polycyanopropylmethylsiloxane-co-polydimethylsiloxanes (PCPMS-co-PDMS) has been demonstrated. The modified polysiloxanes were prepared via a two-step method; (1) the ring-opening polymerization of octamethylcyclotetrasiloxane (D4) and tetramethylcyclotetrasiloxane (D4H), (2) hydrosilylation reaction of the polysiloxane prepolymers with allyl cyanide and allyl glycidyl ether. Molar ratios of D4H and D4 were varied to produce the modified polysiloxanes with differences in polarity. 1H-NMR, 29Si-NMR, 13C-NMR and FTIR were used to monitor the formation of the modified polysiloxanes and DSC was used to study their thermal behaviors (T g, −118 to −68°C). The use of the modified polysiloxanes as an elastomeric component in epoxy–novolac networks was also investigated. TEM and their transition temperatures suggested that the epoxy–novolac networks with high content of PDMS modifiers exhibited microphase separation. The fracture toughness properties of the networks with the polysiloxane modifiers were improved over the controls without polysiloxanes. [Copyright &y& Elsevier]

Cellulose filter paper (CFP) was modified with poly(acrylic acid) (PAA) and/or poly(ethylene glycol)methacrylate (PEGMA), followed by Cu immobilization for 4-nitrophenol (4NP) reduction. Among these samples, Cu-immobilized CFP modified with PEGMA polymer (CFP@PEGMA-Cu) exhibited the highest Cu incorporation of 2.21%. Those having the copolymer (CFP@PAA-co-PEGMA-Cu) demonstrated the highest efficiency, completing 4NP reduction in 3 min with an impressive 99.45% conversion, a high-rate constant (k) of 27.5 × 10−3 s−1, and turnover frequency (TOF) of 18.36 h−1. Notably, the catalysts containing PAA maintained good reusability, preserving 97% conversion upon 9 cycles. These results suggest their promising applications in sustainable catalysis, offering the catalytic potential with simple preparation and low cost required. [ABSTRACT FROM AUTHOR]

This work presents the synthesis of magnetite nanoparticle (MNP) coated with poly(N,N-diethylaminoethyl methacrylate)-b-poly(N-isopropyl acrylamide-st-thiolactone acrylamide) (PDEAEMA-b-P(NIPAAm-st-TlaAm) copolymer and its use in controlled drug release and bio-conjugation. TlaAm units in the copolymer were ring-opened with various alkyl amines to form thiol groups (-SH), followed by thiol-ene coupling reactions with acrylamide-coated MNP and then quaternized to obtain cationic copolymer-MNP assemblies (the size < 200 nm/cluster). The use of alkyl amines having various chain lengths (e.g., 1-propylamine, 1-octylamine, or 1-dodecylamine) in the nucleophilic ring-opening reactions of the thiolactone rings affected their magnetic separation ability, water dispersibility, and release rate of doxorubicin model drug. In all cases, when increasing the temperature, they showed a thermo-responsive behavior as indicated by the decrease in hydrodynamic size and the accelerated drug release rate. These copolymer-MNP assemblies could be used as a novel platform with thermal-triggering controlled drug release and capability for adsorption with any negatively charged biomolecules.MNP coated with multi-functional PDEAEMA-b-P(NIPAAm-st-TlaAm) copolymer and its proposed drug release [ABSTRACT FROM AUTHOR]

• Peptide nucleic acid coated on magnetic support had high selectivity to maize DNA. • Enrichment of zein gene of maize in cereal product using peptide nucleic acid probe. • Unlike conventional methods, contaminated maize can be detected after this process. • Useful for testing of the trace of corn or other causes for allergic diagnostics. Here, we describe DNA enrichment of the zein gene from maize using pyrrolidinyl peptide nucleic acid (PNA) immobilized on a magnetic solid support as a capture element. Magnetite nanoparticles (MNP) with a capacity of 373 pmol PNA/mg and coated with poly(N -acryloylglycine) (PNAG) showed a good response to magnetic field. The PNA probe immobilized on the MNP discriminated between non-complementary and complementary DNA using fluorophore-tagged DNA as a model. We applied this system for the enrichment of the zein gene from maize in eight cereal product samples. After DNA desorption from the MNP, and its amplification via polymerase chain reaction (PCR), gel electrophoresis indicated that only cereal samples containing the zein gene from maize yielded positive results, indicating a high binding specificity between the PNA used and the complementary DNA. This PNA-functionalized MNP is potentially useful as an effective nano-solid support for DNA enrichment from other samples. [ABSTRACT FROM AUTHOR]

pH- and thermoresponsive nanocomposite composed of poly(N-acryloyl glycine) (PNAG) matrix and magnetite nanoparticle (MNP) was synthesized and then used for drug controlled release application. The effects of crosslinkers, e.g., ethylenediamine and tris(2-aminoethyl)amine, and their concentrations (1 and 10 mol%) on the size, magnetic separation ability, and water dispersibility of the nanocomposite were investigated. The nanocomposite crosslinked with tris(2-aminoethyl)amine (size ranging between 50 and 150 nm in diameter) can be rapidly separated by a magnet while maintaining its good dispersibility in water. It can respond to the pH and temperature change as indicated by the changes in its zeta potential and hydrodynamic size. From the in vitro release study, theophylline as a model drug was rapidly released when the pH changed from neutral to acidic/basic conditions or when increasing the temperature from 10°C to 37°C. This novel nanocomposite showed a potential application as a magnetically guidable vehicle for drug controlled release with pH- and thermotriggered mechanism. [ABSTRACT FROM AUTHOR]

Magnetite nanoparticle conjugated with pyrrolidinyl peptide nucleic acid (MNP@PNA) was synthesized for use as both a magnetic nano-support and a probe for specific adsorption with complementary deoxyribonucleic acid (DNA). MNP@PNA with the size ranging between 120 and 170 nm in diameter was prepared via a free radical polymerization of acrylic acid in the presence of acrylamide-grafted MNP to obtain negatively charged magnetic nanoclusters, followed by ionic adsorption with PNA. According to fluorescence spectrophotometry and gel electrophoresis, this MNP@PNA can differentiate between fully matched, single - base mismatched and fully mismatched synthetic DNAs tagged with different fluorophores. UV–vis spectrophotometry and gel electrophoresis indicated that MNP@PNA can be used for specific adsorption with real DNA (zein gene of maize) having complementary sequence with the PNA probe. This novel anionic MNP conjugated with the PNA probe might be potentially applicable for use as a magnetic support for DNA base discrimination and might be a promising tool for testing genetic modification. [ABSTRACT FROM AUTHOR]

Surface modification of magnetic nanoparticle (MNP) with poly(ethylene oxide)- block -poly(2-vinyl-4,4-dimethylazlactone) (PEO- b- PVDM) diblock copolymers and its application as recyclable magnetic nano-support for adsorption with antibody were reported herein. PEO- b -PVDM copolymers were first synthesized via a reversible addition-fragmentation chain-transfer (RAFT) polymerization using poly(ethylene oxide) chain-transfer agent as a macromolecular chain transfer agent to mediate the RAFT polymerization of VDM. They were then grafted on amino-functionalized MNP by coupling with some azlactone rings of the PVDM block to form magnetic nanoclusters with tunable cluster size. The nanocluster size could be tuned by adjusting the chain length of the PVDM block. The nanoclusters were successfully used as efficient and recyclable nano-supports for adsorption with anti-rabbit IgG antibody. They retained higher than 95% adsorption of the antibody during eight adsorption-separation-desorption cycles, indicating the potential feasibility in using this novel hybrid nanocluster as recyclable support in cell separation applications. [ABSTRACT FROM AUTHOR]

Synthesis and drug controlled release properties of thermo-responsive magnetic nanoclusters grafted with poly(N-isopropylacrylamide) (poly(NIPAAm)) and poly(NIPAAm-co-poly(ethylene glycol) methyl ether methacrylate) (PEGMA) copolymers were described. These magnetic nanoclusters were synthesized via an in situ radical polymerization in the presence of acrylamide-grafted magnetic nanoparticles (MNPs). Poly(NIPAAm) provided thermo-responsive properties, while PEGMA played a role in good water dispersibility to the nanoclusters. The ratios of PEGMA to NIPAAm in the (co)polymerization in the presence of the MNPs were fine-tuned such that the nanoclusters with good water dispersibility, good magnetic sensitivity and thermo responsiveness were obtained. The size of the nanoclusters was in the range of 50–100 nm in diameter with about 100–200 particles/cluster. The nanoclusters were well dispersible in water at room temperature and can be suddenly agglomerated when temperature was increased beyond the lower critical solution temperature (LCST) (32 °C). The release behavior of an indomethacin model drug from the nanoclusters was also investigated. These novel magnetic nanoclusters with good dispersibility in water and reversible thermo-responsive properties might be good candidates for the targeting drug controlled release applications. [ABSTRACT FROM AUTHOR]

Carboxymethylchitosan (CMC) hydrogels containing thermo-responsive poly( N -isopropylacrylamide) (poly(NIPAAm)) and pH-responsive poly(acrylic acid) (poly(AA)) were prepared via a free radical polymerization in the presence of hexamethylene-1,6-di-(aminocarboxysulfonate) crosslinking agents. A proper ratio of CMC to NIPAAm and AA used in the reaction was investigated such that the thermo- and pH-responsive properties of the hydrogels were obtained. Water swelling of the hydrogels was improved when the solution pH was in basic conditions (pH 10) or the temperature was below its lower critical solution temperature (LCST). Effects of the change in solution temperature and pH on water swelling properties of the hydrogel as well as the releasing rate of an entrapped drug were also investigated. The hydrogels were not toxic and showed antibacterial activity against Straphylococcus aureus ( S. aureus ). The pH- and thermo-responsive properties of this novel “smart” hydrogel might be efficiently used as dual triggering mechanisms in controlled drug release applications. [ABSTRACT FROM AUTHOR]

This work presented the surface modification of magnetite nanoparticle (MNP) with poly[(t-butyl acrylate)-stat-(poly(ethylene glycol) methyl ether methacrylate)] copolymers (P[(t-BA)-stat-PEGMA]) via a surface-initiated “grafting from” atom transfer radical polymerization (ATRP). Loading molar ratio of t-BA to PEGMA was systematically varied (100 : 0, 75 : 25, 50 : 50, and 25 : 75, resp.) such that the degree of hydrophilicity of the copolymers, affecting the particle dispersibility in water, can be fine-tuned. The reaction progress in each step of the synthesis was monitored via Fourier transform infrared spectroscopy (FTIR). The studies in the reaction kinetics indicated that PEGMA had higher reactivity than that of t-BA in the copolymerizations. Gel permeation chromatography (GPC) indicated that the molecular weights of the copolymers increased with the increase of the monomer conversion. Transmission electron microscopy (TEM) revealed that the particles were spherical with averaged size of 8.1 nm in diameter. Dispersibility of the particles in water was apparently improved when the copolymers were coated as compared to P(t-BA) homopolymer coating. The percentages of MNP and the copolymer in the composites were determined via thermogravimetric analysis (TGA) and their magnetic properties were investigated via vibrating sample magnetometry (VSM). [ABSTRACT FROM AUTHOR]

Magnetite nanoparticles (MNPs) grafted with positively charged poly(2-(diethylamino) ethyl methacrylate (PDEAEMA) were prepared via a combination of atom transfer radical polymerization (ATRP) and 'click' reaction and used as recyclable nanosupports for adsorption with DNA. Alkyne-terminated PDEAEMA was synthesized via ATRP and then 'grafted to' azide-functionalized MNPs. Quaternized PDEAEMA-grafted MNPs were used as recyclable nanosupports for adsorption with negatively charged DNA via electrostatic interactions. The particles with the size of 3-8 nm in diameter were well dispersible in water. They responded to the change in their solution pH as observed by a consistent decrease in hydrodynamic size when solution pH changed from basic to acidic pH. Recycling efficiency of the MNPs was investigated by determining the percent adsorption of the particles after multiple cycles of the adsorption-separation-desorption process. Adsorption ability of the MNPs to T DNA tagged with fluorescein at 5′-position (FAM-dT) retained higher than 80 % after 5-recycling process, indicating that these novel positively charged MNPs might be efficiently used as magnetic nanosupports for any negative biomolecules with good recycling efficiency. [ABSTRACT FROM AUTHOR]

Herein, we report the synthesis of magnetite nanoparticles (MNPs) grafted with poly(poly(ethylene glycol) methyl ether methacrylate- stat-2-vinyl-4,4-dimethylazlactone) copolymers (poly(PEGMA- stat-VDM)) prepared via a surface-initiated atom transfer radical polymerization (ATRP) and used for the immobilization of folic acid (FA). The MNPs were synthesized using a thermal decomposition method and surface functionalized to obtain ATRP-initiating sites. The particle size was in the range of 5-10 nm with the average of 8.0 ± 1.2 nm in diameter. Molar ratio of PEGMA to VDM was systematically varied (0/100, 30/70, 50/50, and 70/30, respectively) in the copolymerization to obtain water dispersible MNP with various amounts of azlactone rings, an electrophilic moiety, on its surface. Grafting density of VDM on the particle surface increased with increased VDM loading in the copolymerization reaction. These copolymer-coated MNPs were well dispersible in water with some nano-scale aggregation after FA functionalization due to hydrophobic character of FA. Since FA is a cancer cell targeting agent, it is anticipated that these novel FA-functionalized MNPs could be used as magnetically guidable vehicle for drug delivery, particularly for cancer treatment. The results of this study warrant a future investigation of this promising system. [ABSTRACT FROM AUTHOR]

In this article, we report the synthesis of magnetite nanoparticles (Fe 3O 4) coated with methoxy poly(ethylene glycol) (mPEG)–polyester amphiphilic block copolymers. The coating polymer layer contains a hydrophobic inner layer of polyester and a hydrophilic corona of mPEG. The copolymers were first prepared via a direct condensation between diacid, diol compounds and mPEG oligomer to obtain a hydrophobic polyester block and hydrophilic mPEG block and then “grafted onto” a magnetite nanoparticle surface. The copolymer composition was varied by changing the structure of the diacid, diol, and the molecular weight ( $$ \overline{M}_{n} $$ M ¯ n ) of the mPEG such that particles with good dispersibility and stability in water were obtained. It was found that the copolymer prepared from 1,6-hexanediol can effectively stabilize the particles in water regardless of the types of diacid and $$ \overline{M}_{n} $$ M ¯ n of mPEG used. The particle size was approximately 10 nm in diameter, and the particle dispersibility in water was quite dependent on the type and concentration of the copolymer used. Thermogravimetric analysis revealed the presence of less than 37 % Fe 3O 4 and about 48–53 % of the copolymer in the complexes. The percent entrapment efficiency and loading efficiency of indomethacin model drug in the copolymer-coated magnetite nanoparticles were 19 and 77 %, respectively. [ABSTRACT FROM AUTHOR]

We are here reporting the surface modification of magnetite nanoparticle (MNP) with amphiphilic steric stabilizer of polydimethylsiloxane (PDMS) and poly(poly(ethylene glycol) methacrylate) (PPEGMA). The main purpose of this work is to obtain the polymeric bilayer surfactant of hydrophobic PDMS inner shell and hydrophilic PPEGMA brush corona on MNP core. Functionalized PDMS was first synthesized and then covalently grafted on the functionalized MNP surface. The PDMS-coated MNP served as a reactive macroinitiator for atom transfer radical polymerization (ATRP) of PPEGMA. Kinetics studies indicated the constant consumption of PEGMA during first 7 h of the ATRP. Transmission electron microscopy showed the average particle size of 7 nm in diameter. Fourier transform infrared spectrophotometry, thermogravimetric analysis, and vibrating sample magnetometry indicated the increase of the percentage of the copolymer in the complex when the ATRP was prolonged. The decrease in its hydrodynamic size from 446 to 162 nm when the ATRP was extended indicated the improvement in its dispersibility in water. In addition, it was found that percent entrapment efficiency and loading efficiency of indomethacin model drug in the PPEGMA-coated MNP was 62 and 27 %, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Surface modification of magnetite nanoparticle (MNP) with poly(poly(ethylene glycol) methyl ether methacrylate-stat-2-vinyl-4,4-dimethylazlactone) copolymers (Poly(PEGMA-stat-VDM)) via atom transfer radical polymerization (ATRP) and its application to anchor thymine peptide nucleic acid (PNA) monomer are reported. ATRP of PEGMA and VDM was first performed in a solution system to optimize the reaction condition and the optimal condition was then applied in the surface-initiated ATRP of MNP. Fourier transform infrared spectroscopy (FTIR) indicated the presence of the copolymer in the MNP complexes. After immobilization of thymine PNA monomer, thermogravimetric analysis (TGA) results indicated that there were 4wt% of the PNA monomer in the complex (1.2μmol/g complex). The existence of the PNA monomer in the complex was also confirmed via FTIR and vibrating sample magnetometry (VSM). The MNP complex with active surface might be efficiently used as magnetically guidable nanosolid support for PNA oligomers and other molecules containing affinity functional groups. [Copyright &y& Elsevier]

Surface modification of magnetite nanoparticles (MNP) with a covalently bonded poly(4-vinylpyridine) (P4VP) by surface-initiated atom transfer radical polymerization (ATRP) is reported in this article. MNP was first prepared via thermal decomposition of Fe(acac) and grafted with an ATRP initiator on its surface. ATRP of 4-vinylpyridine was then initiated from the MNP surface in the presence of CuBr/PMDETA (1,1,4,7,7-pentamethyldiethylenetriamine) catalytic complex in dioxane. FTIR in combination with photocorrelation spectroscopy (PCS), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM) techniques indicated the growth of P4VP on the particle surface with increasing ATRP reaction time. Transmission electron microscopy (TEM) disclosed that the average particle size was 8 nm in diameter with some nanoaggregation observed. The PCS results revealed that decreasing the solution pH enhanced the particle dispersibility because of the positive charge repulsion of the protonated P4VP on the particle surface. TGA was also performed to elucidate the composition of P4VP shell and magnetite core in the hybrid material. [ABSTRACT FROM AUTHOR]

We here report the synthesis of magnetite nanoparticle (MNP) grafted with poly (ethylene glycol) methyl ether methacrylate (PEGMA)-azobenzene acrylate (ABA) statistical copolymer via atom transfer radical polymerization (ATRP) for drug entrapment and photocontrolled release. MNP was synthesized via thermal decomposition of iron (III) acetylacetonate in benzyl alcohol and surface functionalized to obtain ATRP initiating sites. Molar compositions of the copolymer on MNP surface were systematically varied (100:0, 90:10, 70:30, and 50:50 of PEGMA:ABA, respectively) to obtain water dispersible particles with various amounts of azobenzene. The presence of polymeric shell on MNP core was evidenced by transmission electron microscopy (TEM). Drug loading and entrapment efficiencies as well as drug release behavior of the copolymer-MNP complexes were investigated. It was found that when percent of ABA in the copolymers was increased, entrapment and loading efficiencies of prednisolone model drug were enhanced. Releasing rate and percent of the released prednisolone of the complex exposed in UV light were slightly enhanced as compared to the system without UV irradiation. This copolymer-MNP complex with photocontrollable drug release and magnetic field-directed properties is warranted for further studies for potential uses as a novel drug delivery vehicle. [ABSTRACT FROM AUTHOR]

We herein describe a facile synthesis of superparamagnetic magnetite ferrofluids having long-term stability in aqueous dispersions. A single-step thermal decomposition reaction of iron (III) acetylacetonate (Fe(acac)3) was carried out in the presence of poly(ethylene glycol) methyl ether (mPEG) to serve both as a reducing agent and reaction solvent. The role of number average molecular weight ( [image omitted]) of mPEG (350 and 750 g/mol) on the size and properties of the particles was investigated. Fourier-transform infrared spectrophotometry (FTIR) indicated the presence of mPEG in the polymer-magnetite complexes. According to thermogravimetric analysis (TGA), the complexes consisted of 40-66% Fe3O4, depending on the molecular weights of mPEG used. According to the transmission electron micrographs (TEM), the particles prepared in 350 g/mol mPEG exhibited the average diameter of 7.8 ± 1.4 nm, while those in 750 g/mol mPEG were 5.3 ± 1.1 nm. From photocorrelation spectroscopy (PCS) experiments, the size of 350 g/mol mPEG-magnetite complex and 750 g/mol mPEG-magnetite complex were 37.1 ± 1.0 nm and 35.1 ± 0.4 nm, respectively. According to the calculation by the Debye-Scherrer equation, the sizes of 350 g/mol mPEG-magnetite complex and 750 g/mol mPEG-magnetite complex were 7.7 and 6.6 nm, respectively. They were highly crystalline and exhibited superparamagnetic properties. They were stable in aqueous dispersions with insignificant aggregation after 6 weeks of preparing. These stable, non-toxic dispersions might be potentially used in magnetically targeted biomedical applications. [ABSTRACT FROM AUTHOR]

Abstract: Synthesis and properties of semi-interpenetrating polymer networks (semi-IPNs) based on polydimethylsiloxane (PDMS)/poly(ethylene glycol) (PEG)-modified chitosan were studied. 1–20wt% of PDMS or PEG was interpenetrated into chitosan hydrogels having 10wt% of hexamethylene-1,6-di-(aminocarboxysulfonate) (HDA) as a water-soluble crosslinker. PDMS prepolymer was synthesized via acid-catalyzed ring-opening polymerization of octamethylcyclotetrasiloxane (D4), followed by hydrosilylation reaction with allyl alcohol to obtain hydroxyl-terminated PDMS. Effect of PDMS/PEG contents (1–20wt%) and their molecular weights (2000 and 8000g/mol) in chitosan semi-IPNs on percent crosslinking, water swelling properties, thermal stability, surface properties, water vapor permeability and tensile properties were investigated. Percent crosslinking of the PDMS/PEG-chitosan semi-IPNs ranged between 42% and 74% depending on molecular weight and percent of PDMS/PEG added. PDMS and PEG in the semi-IPNs enhanced water swellability and water vapor permeability of the films. Also, PDMS/PEG in chitosan semi-IPNs enhanced their thermal stability and surface hydrophobicity, while their tensile properties were sacrificed. [Copyright &y& Elsevier]

Abstract: Preparation and properties of carboxymethylchitosan (CMC) modified with polyurethane (PU) containing poly(ethylene adipate) (PEA) as a soft segment is described. Urethane prepolymer was first synthesized by the reaction of PEA with an excess of 1,6-hexamethylene diisocyanate (HDI) to terminate its ends with isocyanate functional groups, followed by chain extension reaction using ethylene glycol as a chain extender. Its chemical structure was characterized by 1H NMR and FTIR, molecular weight by GPC, and thermal behavior by DSC. To prepare PU-modified CMC (CMC-PU), 1–60wt% of PU were introduced into the CMC solution of THF:H2O mixture (50:50 v/v) in the presence of 10wt% of hexamethylene-1,6-di-(aminocarboxysulfonate) (HDA) to increase network density. Formation of the network structure was confirmed by investigating percent crosslinking and water swelling properties of CMC-PU compared to CMC network without PU. When percent of PU increased from 1 to 60wt%, percent crosslinking of CMC-PU gradually increased up to 82%, whereas equilibrium water content (EWC) dropped and retained at 1000%. SEM showed microphase separation of PU (10–50μm) thoroughly dispersed in CMC surface and in the bulk. In addition, CMC-PU exhibited a slight enhancement in toughness properties. Cytotoxicity and biocompatibility tests indicated that CMC-PU was non-toxic. [Copyright &y& Elsevier]

Abstract: In this work, we report a synthetic method of water dispersible magnetite nanoparticles having oleic acid and poly(ethylene glycol) methyl ether–poly(ɛ-caprolactone) (mPEG–PCL) amphiphilic block copolymer as polymeric stabilizers. The particles were prepared by coprecipitation of Fe(II) and Fe(III) in NH4OH and had bilayer surface with hydrophobic inner layer and hydrophilic corona. mPEG–PCL copolymer was synthesized by a ring-opening polymerization of ɛ-caprolactone using mPEG as a macroinitiator in the presence of stannous octoate catalyst. FTIR and thermogravimetric analysis (TGA) indicated the presence of the copolymer on the particle surface. Roles of reaction parameters, such as stabilizer concentrations and time of ultrasonicating treatment, on percent of magnetite in the complex and its magnetic properties were investigated. Transmission electron microscopy (TEM) showed the average particle size about 9.0±1.1nm in diameter. Vibrating sample magnetometry (VSM) measurement indicated that the magnetite nanoparticles were superparamagnetic at room temperature. Approximately 6.8±0.5% of indomethacin model drug (68μg/mg of magnetite) was effectively entrapped on the particles. [Copyright &y& Elsevier]

Abstract: In the present contribution, successful preparation of ultrafine fibers of poly(ethylene glycol)–polydimethylsiloxane–poly(ethylene glycol) (PEG–PDMS–PEG) triblock copolymer in its blends with poly(ethylene oxide) (PEO) via electrospinning process was reported for the first time. Chloroform was used as the solvent, the compositional weight ratios between the copolymer and PEO were 80/20, 70/30, and 60/40 and the total concentration of the solutions was either 4 or 6% w/v. While pure PEG–PDMS–PEG solutions in chloroform were not electrospinnable into fibers, the solutions that contained PEO were. The improvement in the electrospinnability of the PEG–PDMS–PEG solutions in the presence of PEO was thought to be due to the increase in the viscosity of the resulting solutions. The average diameter of the fibers obtained ranged between 2.3 and 2.8 μm. Fourier-transformed infrared spectroscopy measurements confirmed the existence of the copolymer within the as-spun blend fibers. [Copyright &y& Elsevier]