Metha Rutnakornpituk

Multi-responsive magnetic microsphere of poly(N-isopropylacrylamide)/carboxymethylchitosan hydrogel for drug controlled release

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±1.0μm 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.

Recyclable magnetite nanoparticle coated with cationic polymers for adsorption of DNA

Abstract Magnetite nanoparticle (MNP) grafted with a cationic copolymer between poly(2-(N,N-diethylamino) ethyl methacrylate) and poly(poly(ethylene glycol) methyl ether methacrylate)) for efficient and recyclable adsorption of 5’-fluorescein-tagged DNA (FAM-dT9) was prepared. MNP having highest degree of positive charge (+32.1 ± 1.9 mV) retained 100% adsorption of FAM-dT9 during eight adsorption–separation–desorption cycles. The MNP having lower degree of positive charge showed a slight decrease in adsorption percentages (94–98% adsorption) after multiple recycling processes. This biocompatible hybrid material with charged surface and magnetic-responsive properties might be applicable for use as a nanosolid support for efficient and facile separation of various bioentities.

Recyclable magnetic nanocluster crosslinked with poly(ethylene oxide)-block-poly(2-vinyl-4,4-dimethylazlactone) copolymer for adsorption with antibody

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.

Poly(acrylic acid)-grafted magnetite nanoparticle conjugated with pyrrolidinyl peptide nucleic acid for specific adsorption with real DNA

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.

Stable dispersions of poly(ethylene glycol) methyl ether–magnetite complexes in water

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 ( ) 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.