Characterization of a heptapeptide-modified microsphere for oriented antibody immobilization

Oriented immobilization of antibodies is important for the effective recognition of target antigens. In this paper, a heptapeptide ligand, HWRGWVC (HC7), was modified onto non-porous mono-sized poly (glyceryl methacrylate) (pGMA) microspheres (named pGMA-HC7) to explore the antibody immobilization behaviors. Characterization of the microspheres by particle size analyzer, scanning electron microscopy, Fourier transform infrared spectroscopy, and reversed-phase chromatography proved the success of each fabrication step. The capacity and activity of antibody immobilization through HC7 were studied using immunoglobulin G (IgG) as a model antibody and horseradish peroxidase (HRP) as a model antigen. Additionally, IgG immobilizations on pGMA microspheres by nonspecific adsorption and covalent coupling through carbodiimide chemistry were conducted for comparison. pGMA-HC7 exhibited an IgG adsorption capacity of 3-4 mg/g in 10 min by the specific binding of HC7 without nonspecific interactions. Notably, the ligand HC7 showed a by two orders of magnitude stronger affinity for IgG than its original hexapeptide ligand HWRGWV. Moreover, the capacity and activity of the immobilized anti-HRP antibody on pGMA-HC7 were 1.6-fold and 3-fold higher than those of the covalent coupling, respectively. The results proved the superior role of HWRGWVC in the affinity binding of antibody and the potential of pGMA-HC7-25 in immunoassay and immunodiagnostic applications.

Mechanistic Investigation of Surfactant-Free Emulsion Polymerization Using Magnetite Nanoparticles Modified by Citric Acid as Stabilizers

Fe₃O₄-armored latexes were successfully synthesized by using modified Fe₃O₄ (IO) nanoparticles as stabilizers without a surfactant. The particle size, conversion, and particle number density of latex particles during the formation process were studied in detail. The surface charge density and the particle size evolutions of latexes were studied by dynamic light scattering. The use of scanning electron microscopy confirmed that IO nanoparticles were adsorbed on the polymer particle surface. Furthermore, the efficiency of iron oxide incorporation (IE) was evaluated by thermogravimetric analysis. The effect of pH, solid content, and zeta potential of IO nanoparticles on the results of polymerization was also discussed in detail. Attempts were made to explain the change of latex particle surface charge density by using Guy-Chapman-Stern's electric double layer theory. In addition, the effect of ionic strength of ammonium sulfate on particle number density of latex particles was described using P. John Feeney's equation. Finally, the mechanistic insights were discussed by studying polymerization kinetics.

Molecular mechanisms for delicately tuning the morphology and properties of Fe3O4 nanoparticle clusters

After being oxidized, dihydric alcohols drive the formation of monodisperse Fe₃O₄ particle clusters.

Mangiferin loaded magnetic PCEC microspheres: preparation, characterization and antitumor activity studies in vitro

Mangiferin is a promising effective chemopreventive agent against various tumors. However, its clinical use is limited by poor water solubility and low bioavailability. In this article, mangiferin loaded magnetic PCEC microspheres (MG-MS) were designed, characterized and the antitumor activity of MG-MS was evaluated in vitro. The magnetic nanoparticles (MNP) were synthesized via the high-temperature reaction of iron acetylacetonate in phenyl ether in the presence of oleic acid and oleylamine. Poly (ε-caprolactone)-poly (ethyleneglycol)-poly (ε-caprolactone) (PCL-PEG-PCL, PCEC) copolymers were formed by ring-opening copolymerization of ε-CL initiated by PEG-diol using Sn(Oct)₂ as a catalyst and MG-MS were prepared by solvent diffusion method. MNP, PCEC copolymer, and MG-MS were characterized by GPC, TEM, XRD, FT-IR, ¹H-NMP and Malvern Laser Particle Sizer. Meanwhile, the antiproliferative activity in vitro and in vitro release behavior of this microspheres were studied in detail. The results indicate that the obtained magnetic microspheres might have great potential as an effective carrier for mangiferin used in cancer chemotherapy.

Fabrication of magnetic-antimicrobial-fluorescent multifunctional hybrid microspheres and their properties

Novel magnetic-antimicrobial-fluorescent multifunctional hybrid microspheres with well-defined nanostructure were synthesized by the aid of a poly(glycidyl methacrylate) (PGMA) template. The hybrid microspheres were fully characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and digital fluorescence microscope. The as-synthesized microspheres PGMA, amino-modified PGMA (NH₂-PGMA) and magnetic PGMA (M-PGMA) have a spherical shape with a smooth surface and fine monodispersity. M-PGMA microspheres are super-paramagnetic, and their saturated magnetic field is 4.608 emu·g⁻¹, which made M-PGMA efficiently separable from aqueous solution by an external magnetic field. After poly(haxemethylene guanidine hydrochloride) (PHGH) functionalization, the resultant microspheres exhibit excellent antibacterial performance against both Gram-positive and Gram-negative bacteria. The fluorescence feature originating from the quantum dot CdTe endowed the hybrid microspheres with biological functions, such as targeted localization and biological monitoring functions. Combination of magnetism, antibiosis and fluorescence into one single hybrid microsphere opens up the possibility of the extensive study of multifunctional materials and widens the potential applications.

Monodispersed magnetic polystyrene beads with excellent colloidal stability and strong magnetic response

Monodispersed polystyrene beads incorporated with Fe(3) O(4) nanoparticles are prepared via dispersion polymerization. The resultant magnetic beads present well-defined composite structures, excellent colloidal stability, and strong magnetic response. The formation mechanism for the monodispersed composite beads, incorporated with preformed Fe(3) O(4) nanocrystals, was investigated. The potential applications of the monodispersed magnetic beads in bacteria capturing were demonstrated. After being coated with anti-Salmonella CSA-1 antibody, the magnetic beads show capturing efficiencies of >99.4% in isolating Salmonella sp.

Synthesis of cross-linked carboxyl poly(glycerol methacrylate) and its application for the controlled release of doxorubicin

A series of polymers were synthesized by cross-linking carboxyl poly(glycerol methacrylate) (PGOHMA) using hexamethylene diisocyanate (HDI). The structures and molecular weight were characterized by ¹H NMR and gel permeation chromatography (GPC). Nanoparticles were then fabricated for encapsulation of doxorubicin hydrochloride (DOX). The encapsulation and release were affected by the chemical structure and degree of cross-linking of the polymers. The polymers were quite effective in the encapsulation of DOX, and exhibited pH-dependent drug release. Specifically, the stability of nanoparticles in neutral pH was significant enhanced and the release rate was enhanced at acidic pH after cross-linking, which could be potential useful as a controlled drug release carrier, especially for anti-cancer drug.

High-capacity adsorption of hexavalent chromium from aqueous solution using magnetic microspheres by surface dendrimer graft modification

The magnetic poly-(methyl acrylate-divinyl benzene) (MA-DVB) microspheres with micron size were synthesized by modified suspension polymerization method. Through stepwise reaction with methyl acrylate (MA) and ethylenediamine (EDA), the magnetic poly-(MA-DVB) microspheres with surface dendrimer containing amino groups were obtained. The above mentioned magnetic microspheres were applied for the adsorption of hexavalent chromium from aqueous solution. The effects of solution pH value, adsorption temperature, and adsorption and desorption of Cr(VI) were studied. The results showed that the optimum pH value for Cr(VI) adsorption was found at pH=3, and the adsorption capacity increased with the increase in adsorption temperature. The adsorption equilibrium of Cr(VI) was obtained in about 12 min and more than 98% of adsorbed Cr(VI) were desorbed from the magnetic microspheres in about 30 min using Na(2)SO(4) solution. By fitting the experimental data to Langmuir equation, the maximum capacity for Cr(VI) of magnetic poly-(MA-DVB) microspheres was estimated at 231.8 mg/g.

Facile synthesis of monodisperse superparamagnetic Fe3O4/PMMA composite nanospheres with high magnetization

Monodisperse superparamagnetic Fe(3)O(4)/polymethyl methacrylate (PMMA) composite nanospheres with high saturation magnetization were successfully prepared by a facile novel miniemulsion polymerization method. The ferrofluid, MMA monomer and surfactants were co-sonicated and emulsified to form stable miniemulsion for polymerization. The samples were characterized by DLS, TEM, FTIR, XRD, TGA and VSM. The diameter of the Fe(3)O(4)/PMMA composite nanospheres by DLS was close to 90 nm with corresponding polydispersity index (PDI) as small as 0.099, which indicated that the nanospheres have excellent homogeneity in aqueous medium. The TEM results implied that the Fe(3)O(4)/PMMA composite nanospheres had a perfect core-shell structure with about 3 nm thin PMMA shells, and the core was composed of many homogeneous and closely packed Fe(3)O(4) nanoparticles. VSM and TGA showed that the Fe(3)O(4)/PMMA composite nanospheres with at least 65% high magnetite content were superparamagnetic, and the saturation magnetization was as high as around 39 emu g(-1) (total mass), which was only decreased by 17% compared with the initial bare Fe(3)O(4) nanoparticles.

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%.

Preparation of monodisperse magnetic polymer microspheres by swelling and thermolysis technique

A novel process for the preparation of monodisperse magnetic polymer microspheres by uniquely combining swelling and thermolysis technique was reported. The monodisperse polystyrene microspheres were first prepared by dispersion polymerization and swelled in chloroform. Then, ferric oleate was dispersed in chloroform as a precursor and impregnated into the swollen polymer microspheres. Subsequently, the iron oxide nanoparticles were formed within the polymer matrix by thermal decomposition of ferric oleate. The morphology, inner structure, and magnetic properties of the magnetic polymer microspheres were studied with a field emission scanning electron microscope (SEM), transmission electron microscope (TEM), and superconducting quantum interference device (SQUID) magnetometer. The results showed that the average diameter of the magnetic polymer microspheres was 5.1 microm with a standard deviation of 0.106, and the magnetic polymer microspheres with saturation magnetization of 12.6 emu/g exhibited distinct superparamagnetic characteristics at room temperature. More interestingly, the magnetite nanoparticles with a spinel structure are evenly distributed over the whole area of the polymer microspheres. These magnetic polymer microspheres have potential applications in biotechnology.

Magnetic PECA nanoparticles as drug carriers for targeted delivery: Synthesis and release characteristics

Magnetic poly(ethyl-2-cyanoacrylate) (PECA) nanoparticles containing anti-cancer drugs (Cisplatin and Gemcitabine) were prepared by inter-facial polymerization. The spherical nanoparticles (d = 250 +/- 15 nm) with smooth surfaces and moderately uniform size distributions were obtained. The amount of magnetite encapsulated inside the polymer matrix was increased up to 14.26% (w/w) by controlling the initial weight ratio of monomer/magnetite. It was found that the amount of Cisplatin encapsulated in the magnetic nanoparticle is much higher than that of Gemcitabine because Cisplatin (hydrophobic) is highly soluble in the oil phase and encapsulated easier inside nanoparticles compared to Gemcitabine (hydrophilic). The presence of magnetite and its super-paramagnetic characteristic were confirmed by FTIR spectra and VSM. In-vitro experiments of drug release and magnetic mobility under external magnetic field demonstrated that magnetic poly(ethyl-2-cyanoacrylate) (PECA) nanoparticles can be a highly versatile magnetic drug carrier with sustained release behaviour and sufficient magnetic susceptibility.