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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]

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]