Effect of the reaction parameters on the particle size in the dispersion polymerization of 2-hydroxyethyl and glycidyl methacrylate in the presence of a ferrofluid

Development of Cotton Fabrics via EVA/SiO2/Al2O3 Nanocomposite Prepared by γ-Irradiation for Waterproof and Fire Retardant Applications

Development of cotton fabric (CF) properties using nanocomposites via coating method was of considerable interest for wide applications. This article aims at developing CF properties by coating treatment using ethylene–vinyl-acetate (EVA), silicon dioxide (SiO2), aluminum oxide (Al2O3) nanoparticles and γ-irradiation widely used in waterproof and flame retardant applications. EVA-based nanocomposites, EVA/SiO2, EVA/Al2O3, and EVA/SiO2/Al2O3, were synthesized by γ-irradiation and the highest gel content of 81.2–95.3% was achieved at 30 kGy. The physicochemical properties of EVA-based nanocomposites were characterized by FT-IR, XRD, DSC and SEM techniques. Usage of irradiated EVA and EVA-based nanocomposites for treatment of CF by coating technique was successfully achieved. This technique provides a simple and versatile method leading to excellent uniform and smooth surface morphology without aggregation. The weight gain, mechanical properties, thermal properties, water vapor permeability and flame-retardant properties of the modified CF were evaluated. Moreover, compared with control CF, the resistivity of water absorptivity and hydrophobic property and the thermal stability were gained. The flame retardant properties of CF samples were performed using limited oxygen index (LOI) and vertical burning flame tests. LOI percentages of CF/EVA/SiO2, CF/EVA/Al2O3 and CF/EVA/SiO2/Al2O3 increased to 25.3, 27.5, and 29.3%, respectively. Untreated CF ignited and burned rapidly after 5 s. Meanwhile, the treated CF hold flame resistance properties and the burning time prolonged to 25 s. The results of the treated CF providing revealed hydrophobic and protective capability of the fabrics from being destroyed by burning, and support their further use in waterproof and flame retardant applications of fabrics.

Click chemical assembly and validation of bio-functionalized superparamagnetic hybrid microspheres

Surface derivatized magnetic nanoparticles have been commonly used for magnetic separation. Facile mechanisms are needed to be developed for the design of bio-functionalized magnetic hybrid materials, where the surfaces can be re-generated for the re-use of the developed platforms. Superparamagnetic iron oxide nanoparticles with a diameter below 10 nm were synthesized via a novel microwave-assisted hydrothermal method in the presence of citrate ions, which allowed to obtain uniform and negatively charged nanoparticles. These were then coupled with Poly-l-lysine (PLL), forming micrometer-sized self-assembled spherical entities. Cross-linking the PLL within these microspheres with glutaraldehyde stabilized them chemically and mechanically. The active bio-functionality was introduced by a protein grafting methodology, using m-maleimidobenzoyl-N-hydroxysulfosuccinimide ester (SMBS). The Moringa oleifera Coagulant Protein (MOCP) from a seed extract was employed for its characteristic coagulation activity. The performance of the MOCP functionalized microspheres was evaluated as a function of turbidity removal of problematic colloidal clay from water via magnetic separation, resulting in over 80% of activity within 15 min. Surface of these hybrid materials can be re-generated by treatment with alcohol, allowing their easy magnetic separation and re-use. The rapid and strong response with tunable magnetic property makes these hybrid microspheres a powerful tool for many potential applications, due to the general applicability of the developed methodology.

Synthesis of magnetic nanoparticles with an IDA or TED modified surface for purification and immobilization of poly-histidine tagged proteins

Magnetic nanoparticles (MNPs) chelating with metal ions can specifically interact with poly-histidine peptides and facilitate immobilization and purification of proteins with poly-histidine tags. Fabrication of MNPs is generally complicated and time consuming. In this paper, we report the preparation of Ni(ii) ion chelated MNPs (Ni-MNPs) in two stages for protein immobilization and purification. In the first stage, organic ligands including pentadentate tris (carboxymethyl) ethylenediamine (TED) and tridentate iminodiacetic acid (IDA) and inorganic Fe₃O₄–SiO₂ MNPs were synthesized separately. In the next stage, ligands were grafted to the surface of MNPs and MNPs with a TED or IDA modified surface were acquired, followed by chelating with Ni(ii) ions. The Ni(ii) ion chelated forms of MNPs (Ni-MNPs) were characterized including morphology, surface charge, structure, size distribution and magnetic response. Taking a his-tagged glycoside hydrolase DspB (Dispersin B) as the protein representative, specific interactions were confirmed between DspB and Ni-MNPs. Purification of his-tagged DspB was achieved with Ni-MNPs that exhibited better performance in terms of purity and activity of DspB than commercial Ni-NTA. Ni-MNPs as enzyme carriers for DspB also exhibited good compatibility and reasonable reusability as well as improved performance in various conditions.

This article reports a novel approach for synthesizing magnetic nanoparticles with a modified surface for purification and immobilization of histidine-tagged proteins.

Highly Durable and Thermally Conductive Shell-Coated Phase-Change Capsule as a Thermal Energy Battery

Robust and thermally conductive phase-change capsules (PCCs) can be effectively used as dispersoids for heat transfer fluids (HTFs) to utilize waste heat. Here, we demonstrate PCCs encapsulated with a cross-linked poly(2-hydroxyethyl methacrylate) shell that showed high durability and low thermal hysteresis for effective heat uptake and release. The circulation system was manufactured by mimicking the 4th Generation District Heating (4GDH) system to confirm the heat delivery efficiencies of PCC-dispersed slurries (PCSs) as the HTFs. The enthalpy change of water after it received heat from the PCS improved by up to 41.1% on increasing the amount of PCCs in the PCS. Furthermore, a high PCC recovery of 92 wt % was achieved after 1500 cycles, which accompanied a phase transition. The PCC developed by us can thus enable effective storage/delivery of waste heat-driven energy for zero-energy buildings and a 4GDH system, as well as thermal management of electronics.

Amine functional magnetic nanoparticles via waterborne thiol-ene suspension photopolymerization for antibody immobilization

The modification of magnetic nanoparticles (MNPs) via different routes for biomolecule binding is an attractive area of research. Waterborne thiol-ene suspension photopolymerization (TESP) can be a useful method for preparing functional MNPs. In this study, for the very first time waterborne TESP was performed in the presence of MNPs. Neat MNPs were coated and in situ functionalized with amine groups by using thiol-ene chemistry. Engrailed-2 (EN2) protein, a potential biomarker for various cancers such as prostate cancer, bladder cancer, breast cancer and ovarian cancer, is known to be a strong binder to a specific DNA sequence (50-TAATTA-30) to regulate transcription. Anti-EN2 antibodies were immobilized onto these MNPs by physical adsorption and covalent bonding methods, respectively. The amount of the physically immobilized antibodies (0.54 mg/g) were found to be lower than the loading of the covalently bonded antibodies (1.775 mg/g). The biomarker level in the artificial solutions prepared was determined by enzyme-linked immunosorbent assay. Coated MNPs were characterized by FTIR, TGA, SEM and STEM. After TESP, the average diameter of the neat magnetite nanoparticles increased from ∼15 nm to ∼32 nm.

Thionine-Modified Poly(glycidyl methacrylate) Nanospheres as Labels of Antibodies for Biosensing Applications

Monodisperse poly(glycidyl methacrylate) (PGMA) nanospheres were obtained by emulsifier-free emulsion polymerization and characterized by physicochemical methods. The effects of various reaction parameters on the particle properties were investigated. The particle size was controlled in the range of 350-420 nm. To introduce carboxyl groups, the PGMA nanospheres were hydrolyzed and oxidized with KMnO4. Subsequently, the enzyme horseradish peroxidase (HRP) and the electron mediator thionine were covalently attached to the PGMA nanospheres to obtain an antibody indicator suitable for enzyme-based electrochemical immunosensors. Combined HRP and thionine binding to the nanospheres had beneficial effects for the labeling efficiency and at the same time prevented the formation of soluble electron mediators.

Visualisation of dual radiolabelled poly(lactide-co-glycolide) nanoparticle degradation in vivo using energy-discriminant SPECT

The determination of nanoparticle (NP) stability and degradation in vivo is essential for the accurate evaluation of NP biodistribution in medical applications and for understanding their toxicological effects. Such determination is particularly challenging because NPs are extremely difficult to detect and quantify once distributed in a biological system. Radiolabelling with positron or gamma emitters and subsequent imaging studies using positron emission tomography (PET) or single-photon emission computerised tomography (SPECT) are some of the few valid alternatives. However, NPs that degrade or radionuclides that detach or are released from the NPs can cause artefact. Here, submicron-sized poly(lactide-co-glycolide) nanoparticles (PLGA-NPs) stabilised with bovine serum albumin (BSA) were dual radiolabelled using gamma emitters with different energy spectra incorporated into the core and coating. To label the core, ¹¹¹In-doped iron oxide NPs were encapsulated inside PLGA-NPs during NP preparation, and the BSA coating was labelled by electrophilic substitution using ¹²⁵I. After intravenous administration into rats, energy-discriminant SPECT resolved each radioisotope independently. Imaging revealed different fates for the core and coating, with a fraction of the two radionuclides co-localising in the liver and lungs for long periods of time after administration, suggesting that NPs are stable in these organs. Organ harvesting followed by gamma counting corroborated the SPECT results. The general methodology reported here represents an excellent alternative for visualising the degradation process of multi-labelled NPs in vivo and can be extended to a wide range of engineered NPs.

Co-encapsulation of human serum albumin and superparamagnetic iron oxide in PLGA nanoparticles: part II. Effect of process variables on protein model drug encapsulation efficiency

This study investigates encapsulation efficiency of model drug, encapsulated by magnetic poly d,l-lactic-co-glycolic acid (PLGA) nanoparticles (NPs). This is the following part of our preceding paper, which is referred in this paper as Part I. Magnetic nanoparticles and model drug human serum albumin (HSA)-loaded PLGA NPs were prepared by the double emulsion solvent evaporation method. Among five important process variables, concentration of PLGA and concentration of HSA in the inner aqueous phase along with their cross-effect had the strongest influence on the encapsulation efficiency. Encapsulation efficiency of nanoparticles ranged from 18% to 97% depending on the process conditions. Higher encapsulation efficiencies can be achieved by using low HSA and high PLGA concentrations. The optimization process, carried out by exact mathematical tools using GAMSTM/MINOS software makes it easier to find out optimum process conditions to achieve comparatively high encapsulation efficiency (e.g. 92.3%) for relatively small-sized PLGA NPs (e.g. 155 nm).

Tailoring Magnetic Microspheres with Controlled Porosity

The synthesis of organic and inorganic nano- and microspheres has attracted much interest for a variety of applications ranging from drug delivery to chemical storage and catalysis. We recently demonstrated the assembly of magnetic nanoparticles and polycations into hybrid microspheres in a single-step synthesis via complex coacervation. These microspheres showed viability for bio-applications as indicated by toxicity tests, and are therefore potential targeted drug delivery devices, as they can be directed magnetically. This work reports the recent progress on the potential use of these assemblies in drug release by controlling their porosity. Fluorescein tagged dextran molecules with different MW have been infiltrated into these entities to determine critical pore size by confocal fluorescence microscopy. Different physicochemical characterization results are also presented.

Preparation and characterization of chitosan poly(acrylic acid) magnetic microspheres

Spherical microparticles, capable of responding to magnetic fields, were prepared by encapsulating dextran-coated Fe3O4 nanoparticles into chitosan poly(acrylic acid) (PAA) microspheres template. The obtained magnetic microspheres were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and thermogravimetry (TG). The results showed that the microspheres were formed and demonstrated magnetic behavior in an applied magnetic field. In addition, magnetite particles were well encapsulated and the composite particles have high magnetite content, which was more than 40%.

The Model of Metal Oxide Particle Formation from Water Solutions of Salts

The model describing the formation of metal oxide particles from water solutions of salts was suggested. Dependence of instability constants of metal complexes and ionization constants of oxygen containing inorganic acids on the electron density upon the central ion or atom allows to calculate these values for metal hydroxides. Equations describing the number of metal ions in polyion, the concentration of polyions in solution, the number of metal ions in primary metal oxide particles and their concentration in the system were suggested.

Hydrogels Penetration and Sorption Properties in the Substances Release Controlled Processes

The crosslinked copolymers of 2-hydroxyethylmethacrylate with polyvinylpyrrolidone as granules and membranes have been synthesized and their penetration and sorption-desorption properties have been investigated. The model of mass-transfer from the solid soluble surface through the hydrogel shell has been suggested. The developed materials are able to create encapsulated and granular polymer forms of drugs prolonged release.

Extraction of PCR-ready DNA from Staphylococcus aureus bacteriophages using carboxyl functionalized magnetic nonporous microspheres

Magnetic microspheres P(HEMA-co-EDMA) were used for PCR-ready phage DNA isolation from lysogenic strains of Staphylococcus aureus, including two new clinical isolates. The conditions of phage particle lysis were optimized. The quality of eluted phage DNA was evaluated by PCR. It was demonstrated that PCR-ready phage DNA can be isolated from small volumes of phage lysates (150 microl) by magnetic microspheres. The reported method is very expeditious without using toxic compounds such as phenol or chloroform. It can be used for phage identification and phage gene detection.

Synthesis of magnetic chelating resins functionalized with tetraethylenepentamine for adsorption of molybdate anions from aqueous solutions

Magnetic resins were synthesized through polymerization of glycidyl methacrylate (GMA) in the presence of divinylbenzene (DVB) or N,N'-methylenebisacrylamide (MBA) as hydrophobic or hydrophilic crosslinker, respectively and in presence of suspended magnetite particles. The resins containing (DVB or MBA) as crosslinker were immobilized with tetraethylenepentamine (TEP) to give the amino resins, GMA/DVB/TEP (R1-en) and GMA/MBA/TEP (R2-en), respectively. The uptake behavior of the two resins was studied towards molybdate anions and uptake capacities of 4.24 and 6.18 mmol/g [as (Mo(VI)] were obtained using (R1-en) and (R2-en). Kinetic studies showed that the adsorption followed the pseudo-second-order model pointing the influence of the textural properties of the resin on the rate of adsorption. Thermodynamic data indicated an endothermic adsorption process. The uptake of Mo(VI) and regeneration of the resins were also studied using the column method. Regeneration efficiency up to 90-96% was reached using ammonia buffer.

Continuous production of water dispersible carbon–iron nanocomposites by laser pyrolysis: Application as MRI contrasts

Carbon encapsulated iron/iron-oxide nanoparticles were obtained using laser pyrolysis method. The powders were processed to produce stable and biocompatible colloidal aqueous dispersions. The synthesis method consisted in the laser decomposition of an aerosol of ferrocene solution in toluene. This process generated, in a continuous way and in a single step, a nanocomposite formed by amorphous carbon nanoparticles of 50-100 nm size in which isolated iron based nanoparticles of 3-10 nm size are located. The effect of using different carriers and additives was explored in order to improve the efficiency of the process. The samples after purification by solid-liquid extraction with toluene, were oxidised in concentrated nitric acid solution of sodium chlorate, washed and finally ultrasonically dispersed in 1 mM tri-sodium citrate solutions. The dispersions obtained have hydrodynamic particle size less than 150 nm and are stable in the pH range of 2-11. Finally the shortening of the transversal relaxation time of water protons produced by the dispersed particles was studied in order to test the feasibility of these systems to be traced by magnetic resonance imaging techniques.

Fabrication and characterization of rigid magnetic monodisperse microspheres for protein adsorption

This article describes the fabrication of a rigid magnetic monodisperse bead (M-PGMA-TRI, 4.92 microm) with polyglycidyl methacrylate (PGMA) cross-linked by trimethylolpropane trimethacrylate (TRI). This was realized by adding a proper amount (2%, w/w) of TRI after 3 h of the dispersion-polymerization reaction with the monomer of GMA. The mono-sized microspheres were further processed to introduce magnetic granules by sulfonation and penetration-deposition approaches. The monodisperse bead (M-PGMA) without TRI addition was also fabricated for comparison. The morphology, size and magnetic characteristics of the microspheres were extensively characterized. The M-PGMA-TRI microspheres were nonporous, of smooth surface and superparamagnetic with a saturation magnetization of 13.0 emicro/g. Recycled use of the material for protein adsorption exhibited stability of the magnetic properties of the M-PGMA-TRI, as compared to the significant loss of the saturation magnetization of the M-PGMA. The chemical stability of the M-PGMA-TRI was also confirmed by examining its protein adsorption and magnetic properties after incubation in various solutions such as acidic buffer (pH 2.2) for 24 h. The adsorption capacity of gamma-globulin reached 287.2 mg/g and kept stable in the repeated adsorption/desorption/regeneration cycles. The results indicated that the introduction of 2% TRI was promising for producing rigid magnetic mono-sized microspheres for protein adsorption.