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The application of nanomaterials in the treatment of various types of diseases continues to increase, including the use of silver nanoparticles (AgNPs). However, there still limitation in terms of the research on labelling AgNPs using radioactive compound such as 131I. The aim of this study is to carry out a method on 131I radiolabelling of AgNPs by using Iodogen as an iodination reagent. The radiolabelled 131I-AgNPs were then purified by using Sephadex-25 column chromatography with 0,05 M phosphate buffer solution as mobile phase for the first purification and HEPES solution for the second purification. The radiochemical purity of radiolabelled 131I-AgNPs was then determined by using autoradiography scanner. 131I-AgNPs with a purity 94,5±0,2121% were obtained after the purification. Stability test of the 131I-AgNPs was carried out by determining the radiochemical purity of the 131I-AgNPs on the first day until the fifth day of storage in the room temperature and refrigerator. The best stability of the 131I-AgNPs after purification resulted in radiochemical purity >90% until the fourth day and <90% on the fifth and subsequent days in both storages. This result shows that storage in the refrigerator can be a better choice rather than in the room temperature.

This research is related to the preparation and initial characterization of gadolinium nanoparticles as a Magnetic Resonance Imaging (MRI) contrast agent. Nanomaterial-based contrast agents aim to improve clearer imaging, longer examination retention times with lower toxicity than gadolinium ion-based contrast agents, and evaluate the potential use of MRI contrast agents for early detection of cancer. Gadolinium nanoparticles were synthesized using polyol method with stabilizer and chemical reaction process at high temperature. The stabilizers used are diethylene glycol (DEG) and triethylene glycol (TEG). The reaction process was carried out at 180°C for 4 hours to obtain gadolinium nanoparticles with uniform size and shape. The results of hydrodynamic and visual measurements using DLS and HRTEM instruments on the gadolinium nanoparticles produced were 50 nm and 18 nm, respectively. The results of the characterization of the crystal structure obtained the X-ray diffraction pattern in the crystal plane (222), which is a typical for the Gd2O3 crystal phase. Characterization of chemical bonds using FTIR showed absorption at 1438-1627 cm−1, 1000-1138 cm−1 and 450-795 cm−1 indicated the presence of Gd-O bond vibrations, while absorption at 1310-1466 cm−1 indicated the presence of Gd-O-Gd bonds. This is evidenced by the similarity with the absorption peak of commercial Gd2O3. The content of free Gd3+ ions found in the synthesized products detected was only about 0.99% of the Gd3+ precursors used.

Telah dilakukan penelitian mengenai degradasi zat warna lithol sebagai studi awal penghilangan tinta pada pembuatan kertas recycle dengan menggunakan radiasi gamma dalam medium air. Penelitian ini bertujuan menentukan pH efektif degradasi, menentukan dosis efektif dan menetukan persamaan kinetika degradasi. Proses iradiasi untuk penentuan pH efektif menggunakan dosis 3 kGy dengan variasi pH awal 7, 8, 9 dan 10. Sedangkan untuk penentuan dosis efektif dan penentuan persamaan laju degradasi diiradiasi pada dosis 1, 2, 3, 4, dan 5 kGy dengan pH awal 8. Pengaturan pH diatur dengan meneteskan NaOH 0,1 M. Penentuan pH dan dosis efektif ditentukan dengan menghitung efisiensi degradasi. Efisiensi degradasi dihitung dengan mengukur pengurangan intensitas warna sampel setelah iradiasi menggunakan spektrofotometer UV-VIS. Analisis kualitatif dilakukan dengan mereaksikan cuplikan sampel dengan CaCl2. Hasil penelitian ini menunjukkan,  pH efektif untuk mendegradasi zat warna lithol adalah 7 dengan rerata efisiensi degradasi 97,40%. Tetapi, untuk aplikasi industri kertas recycle pH awal tidak berpengaruh. Dosis efektif untuk mendegradasi zat warna lithol konsentrasi 10 – 200 ppm adalah 4 kGy dengan rerata efisiensi 99,08% dan waktu yang lebih singkat. Untuk aplikasi dalam industri kertas recycle, dosis efektif diperoleh pada 1 kGy dengan konsentrasi zat warna di bawah 20 ppm. Persamaan kinetika degradasi untuk zat warna lithol adalah -(dCA)/dt= -rA=7,2556CA1. Kata kunci: degradasi warna, iradiasi gamma kertas recycle, zat warna lithol