The application of atomic layer deposition in the production of sorbents for 99Mo/99mTc generator.

New production routes for 99Mo are steadily gaining importance. However, the obtained specific activity is much lower than currently produced by the fission of U-235. To be able to supply hospitals with 99Mo/99mTc generators with the desired activity, the adsorption capacity of the column material should be increased. In this paper we have investigated whether the gas phase coating technique Atomic Layer Deposition (ALD), which can deposit ultra-thin layers on high surface area materials, can be used to attain materials with high adsorption capacity for 99Mo. For this purpose, ALD was applied on a silica-core sorbent material to coat it with a thin layer of alumina. This sorbent material shows to have a maximum adsorption capacity of 120 mg/g and has a99mTc elution efficiency of 55 ± 2% based on 3 executive elutions.

Measurement of reaction kinetics of [177Lu]Lu-DOTA-TATE using a microfluidic system.

Microfluidic synthesis techniques can offer improvement over batch syntheses which are currently used for radiopharmaceutical production. These improvements are, for example, better mixing of reactants, more efficient energy transfer, less radiolysis, faster reaction optimization, and overall improved reaction control. However, scale-up challenges hinder the routine clinical use, so the main advantage is currently the ability to optimize reactions rapidly and with low reactant consumption. Translating those results to clinical systems could be done based on calculations, if kinetic constants and diffusion coefficients were known. This study describes a microfluidic system with which it was possible to determine the kinetic association rate constants for the formation of [177Lu]Lu-DOTA-TATE under conditions currently used for clinical production. The kinetic rate constants showed a temperature dependence that followed the Arrhenius equation, allowing the determination of Arrhenius parameters for a Lu-DOTA conjugate (A = 1.24 ± 0.05 × 1019 M-1 s-1, EA = 109.5 ± 0.1 × 103 J mol-1) for the first time. The required reaction time for the formation of [177Lu]Lu-DOTA-TATE (99% yield) at 80 °C was 44 s in a microfluidic channel (100 µm). Simulations done with COMSOL Multiphysics® indicated that processing clinical amounts (3 mL reaction solution) in less than 12 min is possible in a micro- or milli-fluidic system, if the diameter of the reaction channel is increased to over 500 µm. These results show that a continuous, microfluidic system can become a viable alternative to the conventional, batch-wise radiolabelling technique.