Magnetic poly(glycidyl methacrylate)-based microspheres prepared by suspension polymerization in the presence of modified La0.75Sr0.25MnO3 nanoparticles

Magnetic poly(glycidyl methacrylate) microspheres for protein capture

The efficient isolation and concentration of protein antigens from complex biological samples is a critical step in several analytical methods, such as mass spectrometry, flow cytometry and immunochemistry. These techniques take advantage of magnetic microspheres as immunosorbents. The focus of this study was on the development of new superparamagnetic polymer microspheres for the specific isolation of the tumor suppressor protein p53. Monodisperse macroporous poly(glycidyl methacrylate) (PGMA) microspheres measuring approximately 5 μm and containing carboxyl groups were prepared by multistep swelling polymerization of glycidyl methacrylate (GMA), 2-[(methoxycarbonyl)methoxy]ethyl methacrylate (MCMEMA) and ethylene dimethylacrylate (EDMA) as a crosslinker in the presence of cyclohexyl acetate as a porogen. To render the microspheres magnetic, iron oxide was precipitated within their pores; the Fe content in the particles received ∼18 wt%. Nonspecific interactions between the magnetic particles and biological media were minimized by coating the microspheres with poly(ethylene glycol) (PEG) terminated by carboxyl groups. The carboxyl groups of the magnetic PGMA microspheres were conjugated with primary amino groups of mouse monoclonal DO-1 antibody using conventional carbodiimide chemistry. The efficiency of protein p53 capture and the degree of nonspecific adsorption on neat and PEG-coated magnetic microspheres were determined by western blot analysis.

Facile Synthesis of Magnetic Copolymer Microspheres Based on Poly(glycidyl methacrylate-co-N-isopropylacrylamide)/Fe3O4by Suspension Photopolymerization

Magnetic copolymer based on poly(glycidyl methacrylate-co-N-isopropylacrylamide) microspheres was prepared by 2,2-dimethoxy-2-phenylacetophenone- (DMPP-) photo initiated and poly(vinyl alcohol)- (PVA-) stabilized single step suspension photopolymerization. The effect of chemical interaction, morphology, and thermal properties by adding 0.1% w/v Fe3O4in the copolymer was investigated. Infrared analysis (FTIR) showed that (C=C) band disappeared after copolymerization, indicating that the magnetic copolymer microspheres were successfully synthesized and two important bands at 908 cm−1and 1550 cm−1appear. These are associated with the epoxy group stretching of GMA and secondary amide (N–H/C–H) deformation vibration of NIPAAm in magnetic microspheres. The X-ray diffraction (XRD) result proved the incorporation of Fe3O4nanoparticles with copolymer microspheres as peak of Fe3O4was observed. Morphology study revealed that magnetic copolymer exhibited uniform spheres and smoother appearance when entrapped with Fe3O4nanoparticles. The lowest percentage of Fe3O4nanoparticles leached from the copolymer microspheres was obtained at pH 7. Finally, thermal property of the copolymer microspheres was improved by adding a small amount of Fe3O4nanoparticles that has been shown from the thermogram.

Reactive magnetic poly(divinylbenzene-co-glycidyl methacrylate) colloidal particles for specific antigen detection using microcontact printing technique

Epoxy-functionalized magnetic poly(divinylbenzene-co-glycidyl methacrylate) colloidal particles (mPDGs) were prepared by co-polymerization of 1,4-divinylbenzene and glycidyl methacrylate monomers. The reaction was conducted by batch emulsion polymerization in the presence of an oil in water magnetic emulsion as a seed. The chemical composition, morphology, iron oxide content, magnetic properties, particle size and colloidal stability of the prepared magnetic polymer particles were characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, thermal gravimetric analysis, vibrating sample magnetometry, dynamic light scattering, and zeta potential determination, respectively. The prepared mPDGs were immobilized on a self-assembled monolayer of 3-aminopropyltriethoxysilane (APTES)/octadecyltrichlorosilane (OTS), which were patterned on glass using microcontact printing technique, forming mPDGs-APTES/OTS reactive surface. This construction (mPDGs-APTES/OTS) was used as a solid support for immunoassay. The immobilized magnetic particles were bioconjugated with monoclonal anti-human IL-10 antibody to provide specific and selective recognition sites for the recombinant human IL-10 protein (antigen). Fluorescence microscopic examination was carried out to follow this immunoassay using fluorescently labeled anti-human IL-10 antibody. The results obtained proved the successful use of mPDGs-APTES/OTS microcontact printed surfaces in an immunoassay, which can be exploited and integrated into microsystems in order to elaborate medical devices (e.g. biosensors) which could provide rapid analysis at high sensitivity with low volumes of analyte.

New monodisperse magnetic polymer microspheres biofunctionalized for enzyme catalysis and bioaffinity separations

Magnetic macroporous PGMA and PHEMA microspheres containing carboxyl groups are synthesized by multi-step swelling and polymerization followed by precipitation of iron oxide inside the pores. The microspheres are characterized by SEM, IR spectroscopy, AAS, and zeta-potential measurements. Their functional groups enable bioactive ligands of various sizes and chemical structures to couple covalently. The applicability of these monodisperse magnetic microspheres in biospecific catalysis and bioaffinity separation is confirmed by coupling with the enzyme trypsin and huIgG. Trypsin-modified magnetic PGMA-COOH and PHEMA-COOH microspheres are investigated in terms of their enzyme activity, operational and storage stability. The presence of IgG molecules on microspheres is confirmed.