We synthesized magnetic nanoparticles (MNPs) by mixing aqueous solutions of 3d transition metal chlorides ( ) and a sodium metasilicate nonahydrate ( ) in order to produce monodispersed MNPs in a single step. The particle size can be controlled by adjusting the annealing temperature. We characterized the MNPs by X-ray diffraction (XRD), superconducting quantum interference device (SQUID), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR), and zeta-potential measurement. Paramagnetic and superparamagnetic behaviors were found for the obtained samples depending on the particle size ( ？nm). The synthesized MNPs could be modified with the amino-, phenyl-, and carboxy- groups on MNPs' surface by silanization procedure, respectively. The purpose of functionalizing the surface of the nanoscale magnetic particles was to realize subsequent capture and detection with desired other molecules by nanoparticle assisted laser ionization/desorption mass spectrometry. 1. Introduction Nanoscale magnetic particles have attracted much attention because they are able to be transported to targeted locations [1–4] by means of an external magnetic field as well as to be used for data storage [5] and magnetic resonance imaging [6, 7]. Synthesis methods of magnetic nanoparticles (MNPs) have been developed for composing various kinds of MNPs and controlling the sizes in the range of 1–100？nm [8–10]. Coprecipitation method is the most convenient way to synthesize MNPs from metal chloride solution (i.e., iron, manganese, nickel, etc.) by the addition of base solution. MNPs are precipitated under optimum temperature, pH, and ionic strength [11–13] due to solubility change. Nanometer-scale spheres show very interesting characteristic phenomena such as quantum size effect or magnetic quantum tunneling and have intrinsic instability over longer haul for the morphology. To stabilize MNP character, chemical coating on naked MNP surface was developed [14–16]. For example, MNP with 10–20？nm can be stabilized in 2-aminoethanethiol (0.5？M) [14]. Polymer or surfactant coating is also used to protect the MNP configuration and avoid aggregation [17–21]. These techniques can be applied to protection of MNP morphology although we should pay attention to synthesis conditions under the complicated method. We have developed a method for synthesizing MNPs by mixing aqueous solutions of 3d transition metal chlorides (MCL2·nH2O) and a sodium metasilicate nonahydrate (Na2SiO3·9H2O) to obtain monodispersed and bite-sized MNPs in a single step. The particle size depended on the
References
[1]
S. Moritake, S. Taira, Y. Sugiura, M. Setou, and Y. Ichiyanagi, “Magnetic nanoparticle-based mass spectrometry for the detection of biomolecules in cultured cells,” Journal of Nanoscience and Nanotechnology, vol. 9, no. 1, pp. 169–176, 2009.
[2]
S. Moritake, S. Taira, Y. Ichiyanagi et al., “Functionalized nano-magnetic particles for an in vivo delivery system,” Journal of Nanoscience and Nanotechnology, vol. 7, no. 3, pp. 937–944, 2007.
[3]
S. Taira, Y. Z. Du, Y. Hiratsuka, T. Q. P. Uyeda, N. Yumoto, and M. Kodaka, “Loading and unloading of molecular cargo by DNA-conjugated microtubule,” Biotechnology and Bioengineering, vol. 99, no. 3, pp. 734–739, 2008.
[4]
C. Chen, J. Geng, F. Pu, X. Yang, J. Ren, and X. Qu, “Polyvalent nucleic acid/mesoporous silica nanoparticle conjugates: dual stimuli-responsive vehicles for intracellular drug delivery,” Angewandte Chemie, vol. 50, no. 4, pp. 882–886, 2011.
[5]
A. Zentko, V. Kave？ansky, M. Mihalik et al., “Magnetic relaxation and memory effect in nickel-chromium cyanide nanoparticles,” Acta Physica Polonica A, vol. 113, no. 1, pp. 511–514, 2008.
[6]
T. Skajaa, D. P. Cormode, P. A. Jarzyna et al., “The biological properties of iron oxide core high-density lipoprotein in experimental atherosclerosis,” Biomaterials, vol. 32, no. 1, pp. 206–213, 2011.
[7]
Y. M. Huh, Y. W. Jun, H. T. Song et al., “In vivo magnetic resonance detection of cancer by using multifunctional magnetic nanocrystals,” Journal of the American Chemical Society, vol. 127, no. 35, pp. 12387–12391, 2005.
[8]
Z. Wang, P. Xiao, B. Shen, and N. He, “Synthesis of palladium-coated magnetic nanoparticle and its application in Heck reaction,” Colloids and Surfaces A, vol. 276, no. 1–3, pp. 116–121, 2006.
[9]
Y. Ichiyanagi and Y. Kimishima, “Structural, magnetic and thermal characterizations of Fe2O3 nanoparticle systems,” Journal of Thermal Analysis and Calorimetry, vol. 69, no. 3, pp. 919–923, 2002.
[10]
Y. Ichiyanagi and Y. Kimishima, “Magnetic and structural studies of Ni(OH)2 monolayered nanoclusters,” Japanese Journal of Applied Physics, Part 1, vol. 35, no. 4, pp. 2140–2144, 1996.
[11]
Y. Ichiyanagi, T. Uehashi, and S. Yamada, “Magnetic properties of Ni-Zn ferrite nanoparticles,” physica Status Solidi C, vol. 12, pp. 3485–3488, 2004.
[12]
Y. Ichiyanagi, H. Kondoh, T. Yokoyama, K. Okamoto, K. Nagai, and T. Ohta, “X-ray absorption fine-structure study on the Ni(OH)2 monolayer nanoclusters,” Chemical Physics Letters, vol. 379, no. 3-4, pp. 345–350, 2003.
[13]
I. Robinson, L. D. Tung, S. Maenosono, C. W？lti, and N. T. K. Thanh, “Synthesis of core-shell gold coated magnetic nanoparticles and their interaction with thiolated DNA,” Nanoscale, vol. 2, no. 12, pp. 2624–2630, 2010.
[14]
Y. Tanaka and S. Maenosono, “Amine-terminated water-dispersible FePt nanoparticles,” Journal of Magnetism and Magnetic Materials, vol. 320, no. 19, pp. L121–L124, 2008.
[15]
A. H. Latham and M. E. Williams, “Versatile routes toward functional, water-soluble nanoparticles via trifluoroethylester-PEG-thiol ligands,” Langmuir, vol. 22, no. 9, pp. 4319–4326, 2006.
[16]
H. G. Bagaria, E. T. Ada, M. Shamsuzzoha, D. E. Nikles, and D. T. Johnson, “Understanding mercapto ligand exchange on the surface of FePt nanoparticles,” Langmuir, vol. 22, no. 18, pp. 7732–7737, 2006.
[17]
P. C. Scholten and J. A. P. Felius, “The magnetical and rheological behavior of aggregating magnetic suspensions,” Journal of Magnetism and Magnetic Materials, vol. 85, no. 1–3, pp. 107–113, 1990.
[18]
M. De Cuyper and M. Joniau, “Mechanistic aspects of the adsorption of phospholipids onto lauric acid stabilized Fe3O4 nanocolloids,” Langmuir, vol. 7, no. 4, pp. 647–652, 1991.
[19]
A. Wooding, M. Kilner, and D. B. Lambrick, ““Stripped” magnetic particles. Applications of the double surfactant layer principle in the preparation of water-based magnetic fluids,” Journal of Colloid And Interface Science, vol. 149, no. 1, pp. 98–104, 1992.
[20]
E. E. Carpenter, C. T. Seip, and C. J. O'Connor, “Magnetism of nanophase metal and metal alloy particles formed in ordered phases,” Journal of Applied Physics, vol. 85, no. 8, pp. 5184–5186, 1999.
[21]
M. H. Sousa, F. A. Tourinho, J. Depeyrot, G. J. Da Silva, and M. C. F. L. Lara, “New electric double-layered magnetic fluids based on copper, nickel, and zinc ferrite nanostructures,” Journal of Physical Chemistry B, vol. 105, no. 6, pp. 1168–1175, 2001.
[22]
S. Santra, C. Kaittanis, J. Grimm, and J. M. Perez, “Drug/dye-loaded, multifunctional iron oxide nanoparticles for combined targeted cancer therapy and dual optical/magnetic resonance imaging,” Small, vol. 5, no. 16, pp. 1862–1868, 2009.
[23]
P. A. Johnson, H. J. Park, and A. J. Driscoll, “Enzyme nanoparticle fabrication: magnetic nanoparticle synthesis and enzyme immobilization,” Methods in Molecular Biology, vol. 679, pp. 183–191, 2011.
[24]
S. Moritake, S. Taira, T. Hatanaka, M. Setou, and Y. Ichiyanagi, “Preparation of amino acid conjugated nano-magnetic particles for delivery systems,” e-Journal of Surface Science and Nanotechnology, vol. 5, pp. 60–66, 2007.
[25]
S. Taira, Y. Sahashi, S. Shimma, T. Hiroki, and Y. Ichiyanagi, “Nanotrap and mass analysis of aromatic molecules by phenyl group-modified nanoparticle,” Analytical Chemistry, vol. 83, no. 4, pp. 1370–1374, 2011.
[26]
S. Taira, Y. Sahashi, S. Shimma, T. Hiroki, and Y. Ichiyanagi, “Nanotrap and mass analysis of aromatic molecules by phenyl group-modified nanoparticle,” Analytical Chemistry, vol. 83, no. 4, pp. 1370–1374, 2011.
[27]
T. Hiroki, S. Taira, H. Katayanagi et al., “Functional magnetic nanoparticles for use in a drug delivery system,” Journal of Physics, vol. 200, no. 12, Article ID 122003, 2010.
[28]
K. Tanaka, Y. Ido, S. Akita, Y. Yoshida, and T. Yoshida, “Detection of high mass molecules by laser desorption time-of-flight mass spectrometry,” in Proceedings of the 2nd Japan-China Joint Symposium on Mass Spectrometry, p. 185, 1987.
[29]
S. Taira, K. Kitajima, H. Katayanagi, E. Ichiishi, and Y. Ichiyanagi, “Manganese oxide nanoparticle-assisted laser desorption/ionization mass spectrometry for medical applications,” Science and Technology of Advanced Materials, vol. 10, no. 3, Article ID 034602, 2009.
[30]
S. Taira, Y. Sugiura, S. Moritake, S. Shimma, Y. Ichiyanagi, and M. Setou, “Nanoparticle-assisted laser desorption/ionization based mass imaging with cellular resolution,” Analytical Chemistry, vol. 80, no. 12, pp. 4761–4766, 2008.
[31]
S. Taira, I. Osaka, S. Shimma, et al., “Oligonucleotide analysis by nanoparticle-assisted laser desorption/ionization mass spectrometry,” Analyst, vol. 137, no. 9, pp. 2006–2010, 2012.
[32]
D. Cunningham, R. E. Littleford, W. E. Smith et al., “Practical control of SERRS enhancement,” Faraday Discussions, vol. 132, pp. 135–145, 2006.
