Innovation in radiolabeling methods: iodine adsorption characteristics on porous silica nanoparticles

Investigation of NaI adsorption on Porous Silica Nanoparticles (PSN-blank) and functionalized PSN (PSN-NH₂) was conducted to study the possibility of PSN radiolabeling using adsorption techniques. This research aims to study the radiolabeling of ¹³¹I compounds with porous material nanoparticles using the adsorption method. The study began with the adsorption study of NaI (non-radioactive) to understand the initial adsorption behavior on two types of nanoparticles: PSN-Blank and PSN-NH₂. Adsorption parameters such as temperature, time, pH, initial concentration of adsorbate, and functional groups were studied to predict the most influential parameters in the radiolabeling process. The adsorption kinetics were evaluated to determine whether they tended to be pseudo-first or pseudo-second order. The NaI adsorption isotherms on PSN-Blank and PSN-NH₂ at different temperatures were also tested using the Langmuir and Freundlich models. The investigation results showed that the adsorption of NaI on PSN-Blank and PSN-NH₂ was spontaneous, endothermic, tended to obey pseudo-second-order adsorption kinetics, and the adsorption isotherm of the Langmuir model. The activation energy of NaI adsorption on PSN-NH₂ was higher than that on PSN-Blank. After the adsorption characteristics of NaI by PSN and PSN-NH₂ were comprehended, actual radiolabeling experiments using the ¹³¹INaI adsorption were carried out. The radiolabeling results showed, the presence of amine groups increases the adsorption rate of PSN and makes the PSN bond with the labeled compound more stable. The presence of amine groups increases the radiochemical yield and stability of ¹³¹I-labeled PSN compounds.