Effect of lanthanoid shrinkage on surface adsorption of astatine on gold

抄録

Astatine-211 has been touted as a promising radionuclide for cancer treatment, and experiments have been done to show is effectiveness in treating cancer [1,2]. Many experiments bind ²¹¹At to a carrier, most notably gold nanoparticles, to allow the targeting of cancerous areas via cancer-specific targeting molecules. In our previous works, we have studied the adsorption of astatine on gold and found that astatine absorbs stronger to gold than iodine [3]. This is interesting since generally, adsorption of elements of the same group lower down in the periodic table yields smaller adsorption energy [4].

An interesting note is that since astatine is almost at the bottom of the halogen group, it has electrons in the 4f orbital. Unlike the lighter halogens, the presence of 4f orbital induces lanthanoid shrinkage, causing the atomic radius of elements with electtrons in the orbital to become smaller. The effect is noted to go beyond the lanthanoid series, as the subsequent elements also have smaller atomic radii. This lanthanoid shrinkage is also responsible for the difference in adsorption trend of astatine on gold compared to iodine on gold. Iodine, which has no electrons in the 4f orbital, does not get the shrinking effect. More details will be presented in the meeting.

References

[1] L Dziawer, P. Kozminski, S. Mecznska-Wielgosz, M. Pruszynski, M. Lyczko, B. Was, G. Celichowski, J. Grobelny, J. Jastrzebski, A. Bilewicz, RSC Adv. 7, 41024 (2017).

[2] H. Kato, X. Huang, Y. Kadonaga, D. Katayama, K. Ooe, A. Shimoyama, K. Kabayama, A. Toyoshima, A. Shinohara, J. Hatazawa, K. Fukase, J. Nanobiotechnol 19, 223 (2021).

[3] J. Tanudji, S. M. Aspera, H. Kasai, e-J. Surf. Sci. Nanotech. 21 (2023).

[4] I. A. Pasti, S. V. Mentos, Electrochemical Acta 55, 1995 (2010).