Magnetic nanoparticles (MNPs) show great potential for many technological applications due to their superparamagnetic properties. Finding a green approach to producing biocompatible magnetic nanoparticles is of the utmost importance, especially for biomedical purposes. In the present study, the iron oxide nanoparticles were synthesized by a simple green coprecipitation method at a mild temperature, using natural rubber latex (NRL) extracted from Hevea brasiliensis as the capping agent. X-ray diffraction (XRD) patterns revealed a spinel structure of the magnetic nanoparticles (Fe 3 O 4 ). Transmission electron microscopy (TEM) images showed that the core size of MNPs can be controlled by the NRL concentration. The zeta potential measurement of the NRL-coated and uncoated MNPs revealed higher colloidal stability for the NRL-coated MNPs. Fourier transform infrared spectroscopy (FTIR) suggested the presence of hydroxyl groups in the uncoated MNPs, probably due to residual water at the MNP surface. Absence of hydroxyl groups in the NRL-coated samples suggests that the binding of the MNPs to NRL molecules protects the magnetic cores from water, preventing hydration of the nanoparticle surface. Hall magnetometer measurements revealed that the iron oxide nanoparticles are superparamagnetic and that the NRL-coated magnetic nanoparticles have higher magnetization compared to the bare magnetic nanoparticles. Therefore, these results indicate that the NRL is an effective stabilizing agent to cover magnetic nanoparticles for biomedical applications.

engineering involving imaging of magnetization and current distributions. Applications have spanned many disciplines, from applied physics and materials science [1-6] to paleomagnetism and rock magnetism [7-11], biophysics [12-20], and nondestructive testing [21-26]. Instruments based on superconducting quantum interference device (SQUID) sensors currently yield the best field sensitivity but are bulky,

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In this paper we discuss the results obtained with an in-fiber Fabry-Perot interferometer (FPI) used in strain and magnetic field (or force) sensing. The intrinsic FPI was constructed by splicing a small section of a capillary optical fiber between two pieces of standard telecommunication fiber. The sensor was built by attaching the FPI to a magnetostrictive alloy in one configuration and also by attaching the FPI to a small magnet in another. Our sensors were found to be over 4 times more sensitive to magnetic fields and around 10 times less sensitive to temperature when compared to sensors constructed with Fiber Bragg Grating (FBG).