CONTROLLED GROWTH OF IRON OXIDE MAGNETIC NANOPARTICLES VIA COPRECIPITATION METHOD AND NaNO 3 ADDITION. Size controlled magnetic nanoparticle (MNPs) of iron oxide were prepared in the presence of NaNO 3 via co-precipitation method followed by HNO 3 peptizing according to Massart's method. The MNPs size were reduced by addition of NaNO 3 in varied molarity and at different stage of process. As an end product, stable water-base colloids were formed. XRD pattern analysis using Rietveld method confirmed Fe 3 O 4 /-Fe 2 O 3 phase formation with nanoscale crystallite size. This crystallite size significantly decrease with NaNO 3 addition from 12 nm to smaller than 8 nm, and give end-result of decreasing magnetization as measured by VSM. Langevin fitting of magnetic hysteresis curve also revealed the magnetic core size of nearly the same behaviour. TEM results show bigger value for single magnetic nanoparticle of > 10 nm and < 10 nm for MNPs without and with NaNO 3 addition, respectively. However, PSA measurement still trace a low nanoparticle agglomeration of~20 nm, even after surface peptization using HNO 3 . A possible mechanism is proposed to explain these characteristics formation especially of the MNP's size. ABSTRAK PENGENDALIAN PENUMBUHAN NANOPARTIKEL MAGNETIK OKSIDA BESI DENGANMETODA KO-PRESIPITASI DAN PENAMBAHAN NaNO 3 . Nanopartikel magnetik oksida besi dengan ukuran terkendali telah dipreparasi dengan metoda ko-presipitasi dan penambahan NaNO 3 serta peptisasi HNO 3 mengikuti metoda Massart. Pengendalian ukuran nanopartikel magnetik dilakukan dengan memvariasikan nilai molaritas serta tahapan proses penambahan NaNO 3 . Hasil analisis pola difraksi sinar-X dengan metoda Rietveld mengkonfirmasi terbentuknya fasa Fe 3 O 4 /-Fe 2 O 3 dengan penurunan ukuran kristalit dari 12 nm untuk sampel tanpa penambahan NaNO 3 menjadi 8 nm setelah penambahan NaNO 3 . Pengecilan ukuran ini juga teranalisis pada hasil fitting kurva magnetisasi dengan persamaan Langevin serta pengamatan dengan TEM. Namun hasil pengukuran PSA tetap mendeteksi adanya aglomerasi nanopartikel dengan ukuran aglomerat terkecil~20 nm meski telah dilakukan upaya peptisasi dengan HNO 3 . Mengacu pada berbagai data karakteristik dan hasil analisis ini, mekanisme pengendalian pertumbuhan ukuran partikel ini dicoba dijelaskan dalam artikel ini.

This article discusses the performance of Vibrating Sample Magnetometer (VSM) Oxford 1.2 H in characterizing the magnetic samples in liquid form. Samples of water-based ferrofluid placed in a capillary tube pipe. Measurement of samples with varied position, volume and concentration as well as repeated measurements are carried out to evaluate the performance. From these series of measurements, it brings that optimal volume range with measurement results that can still be accounted for is 10 µL, with samples being in equilibrium position within the pick-up coil. The smallest sample concentration which still can be observed quantitatively is 0.332 mg/mL. Repeatability test gives the value of the magnetic moment deviation of ~ 4%. The accuracy of the sample preparation and positioning of the samples is analyzed being a major factor which causes this measurement error. In general it can be concluded that the liquid sample measurement will give better results when using reverse pipetting mode when putting the liquid samples within capillary tube using a micropipette. The measurement should be done as soon as possible after preparation. Keywords: Vibrating sampel magnetometer (VSM), ferrofluid, volume, concentration, repeatibility Abstrak Artikel ini membahas tentang unjuk kerja Vibrating Sample Magnetometer (VSM) Oxford 1.2H dalam mengkarakterisasi sampel magnetik dalam bentuk cair. Sampel cair berupa ferrofluid berbasis air ditempatkan dalam pipa kapiler tertutup. Posisi, volume dan konsentrasi sampel divariasikan serta dilakukan pengukuran berulang untuk menguji kedapat-ulangan (repeatibility). Dari serangkaian pengukuran yang dilakukan diperoleh bahwa range volume optimal dengan hasil pengukuran yang masih bisa dipertanggungjawabkan adalah 10 µL dengan posisi sampel setimbang serta berada dalam daerah antara pick-up coil. Sedangkan konsentrasi terkecil yang masih dapat diamati secara kuantitatif adalah sampel dengan konsentrasi 0,332 mg/mL. Uji kedapat-ulangan memberikan nilai penyimpangan momen magnetik total ~4%. Keakuratan penyiapan sampel dan penempatan sampel merupakan faktor utama penyebab penyimpangan. Secara umum dapat disimpulkan bahwa pengukuran sampel cair akan memberikan hasil yang lebih baik bila digunakan mode tekanan positif (reverse pipetting) pada saat memasukkan sampel cair dengan micropipette serta sampel sesegera mungkin diukur setelah preparasi Kata Kunci: Vibrating sampel magnetometer (VSM), ferrofluid, volume, konsentrasi, kedapat-ulangan. PendahuluanPenggunaan bahan magnetik dalam bentuk cair/koloid (ferrofluid) makin meningkat pada berbagai bidang. Secara umum ferrofluid didefinisikan sebagai suspensi koloid stabil dari nanopartikel magnetik yang tersebar dalam medium cair. Bahan ini mempunyai aplikasi yang luas mulai dari aplikasi sebagai pelumas pada sistem mekanis hingga aplikasi di bidang biomedis sebagai bahan pengontras MRI serta sebagai agen hipertermi [1] [2]. Berbagai aplikasi ini mengeksplor beberapa sifat ferrofluid terutama sifat mudah-alir dan mudah-kendali nya dengan m...

No abstract

SYNTHESIS AND CHARACTERIZATION OF HPMC/HAp/Fe3O4 COMPOSITE FOR HYPERTHERMIA APPLICATION. Magnetic material become subject of intense research for hyperthermia application, and injectable magnetic hyperthermia for bone cancer is one of this research interest. In this study, composite of hydroxyapatite (HAp) and Fe3O4 in Hydroxypropyl-methyl cellulose (HPMC) matrix (HPMC/HAp/Fe3O4) has been synthesized in gel form that are expected can be applied for injectable bone substitute (IBS) in hyperthermia therapy. Composites were made using conventional methods by mixing HAp powder with ferrofluid Fe3O4 in HPMC solution. The composition of the composites were varied with the mass comparison of HPMC: HAp: Fe3O4 was 1: 0: 0; 1: 3: 0; 1: 2: 0.5; 1: 1: 0.25; and 1: 0: 3. The physical, chemical, and magnetic properties of the composites were characterized using X-Ray Diffractometer (XRD), Fourier Transform Infrared Spectrometry (FT-IR), Particle Size Analyzer (PSA), and Vibrating Sample Magnetometer (VSM). The XRD characterization results of the HPMC/HAp/Fe3O4 composite showed the crystalline phase of the constituent components. Saturation magnetization of the HPMC/HAp/Fe3O4 composite was 2.72 emu/g and 1.79 emu/g for the composition of 1: 2: 0.5 and 1:1:0.25 respectively. HPMC/HAp/Fe3O4 composite has superparamagnetic and biocompatible properties, so that can be applied as IBS in hyperthermia therapy for bone cancer.

SYNTHESISAND CHARACTERIZATION OF MAGNETIC-HYDROXYAPATITE COMPOSITE USING ONE SPOT COPRECIPITATION METHOD. Nanocomposite of magnetic-hydroxyapatite (MHAP) has the potential to be developed as a biocompatible-biodegradable material for bone cancer diagnosis and therapy. In this study, such composite materials have been successfully synthesized by one-spot coprecipitation method and ultrasonic dispersion. The mass ratio between magnetic and hydroxyapatite fraction were varied to 30:70 (K30), 40:60 (K40) and 50:50 (K50). X-Ray Diffractometer, Transmission Electron Microscope, Fourier Transform-Infrared Spectrometer and Vibrating Sample Magnetometer were used for characterizing the properties of MHAP composite. X-Ray Diffraction pattern reveals the presence of magnetic and HAP phases, confirm the establishment of MHAP composite system. TEM image and FT-IR spectra shows the spherical morphology of magnetic nanoparticles with a size of~10 nm entrapped within HAP nanorod structure without any chemical bonding between the two phase. With such physical composite mechanism and higher energy induce by ultrasonic dispersion process, magnetic fraction of even 50% mass fraction could still be loaded into HAP matrix and provide maximum magnetisation value of 34.6 emu/g. This magnetization value is higher than the result of another study of MHAP synthesis, giving better prospect for bone cancer diagnosis and therapy.