Hydroxyapatite based materials including nanoparticles (HAp-NPs) are widely used in medicine because of their stability in various biological media . The HAp-NPs also belong to promising drug carrier systems for medicinal radionuclides such as F-18 as the part of multipurpose theranostic system with other therapeutic and diagnostic radionuclides . HAp-NPs can show uptake by cancer tissue due to EPR effect, therefore diagnostic and therapy of the diseases are expected to be very accurate and beneficial.
Fluorine-18 was obtained in a form of irradiated water for medicinal purposes and was used without further purification. The labelling was performed with ready-made HAp-NPs (5 mg) in 0.9% NaCl solution. Labelling was carried out with pristine NPs and NPs decorated with selected ligands: NPMIDA and IDMP (0.05 mg). Experiments with pristine HAp-NPs have shown F-18 uptake with maximal yield of about 93% (15 min incubation), while NPMIDA-HAp-NPs and IDMP-HAp-NPs have shown yields 99% and 98% respectively. Further experiments have shown that uptake kinetics is quite fast (over 90% yield within 5 minutes). In vitro stability experiments have shown good stability of 18F-HAp-NPs nanoconstruct in a bovine blood serum and plasma (more than 90% of activity remained bound to the NPs in 7,5 hours), and slightly worth results in 5% albumin solution and physiological saline (under 90%). NPMIDA and IDMP decorated nanoparticles have shown good stability in a physiological saline (over 95% of bound activity in 6 hours), between 65 – 80% in serum and 40 – 50% in 5% albumin solution.
Acknowledgment: AZV ČR - 16-30544A.
 E. M. Rivera-Munoz, in Biomedical Engineering – Frontiers and Challenges, (Ed: R. Fazel), Rijeka, Croatia, 2011, pp. 75-98.
 B. Sandhöfer, M. Meckel et al, Appl. Mater. Interfaces. 2015; 7, 19.