Chemical and Physical Characterisation of Human Serum Albumin Nanocolloids: Kinetics, Strength and Specificity of Bonds with 99mTc and 68Ga

Manuela Marenco; Letizia Canziani; Gianluca De Matteis; Giorgio Cavenaghi; Carlo Aprile; Lorenzo Lodola

doi:10.3390/nano11071776

Chemical and Physical Characterisation of Human Serum Albumin Nanocolloids: Kinetics, Strength and Specificity of Bonds with ^99mTc and ⁶⁸Ga

Nanomaterials (Basel). 2021 Jul 8;11(7):1776. doi: 10.3390/nano11071776.

Authors

Manuela Marenco¹, Letizia Canziani¹, Gianluca De Matteis¹, Giorgio Cavenaghi¹, Carlo Aprile², Lorenzo Lodola¹

Affiliations

¹ Fondazione IRCCS Policlinico San Matteo, Nuclear Medicine Unit, 27100 Pavia, Italy.
² National Center for Oncological Hadrontherapy (CNAO), 27100 Pavia, Italy.

Abstract

Nanoparticles of Human Serum Albumin (NC) labelled with ^99mTc are widely used in Nuclear Medicine and represent the gold-standard for the intraoperative detection of the sentinel lymph node in many kinds of cancer, mainly breast cancer and melanoma. A significant amount of radionuclides can be incorporated into the HSA particle, due to the multiple binding sites, and HSA-based nanocolloid catabolism is a fast and easy process that results in innocuous degradation products. NCs labelled with different isotopes represent an interesting radiopharmaceutical for extending diagnostic accuracy and surgical outcome, but the knowledge of the chemical bond between NCs and isotopes has not been fully elucidated, including information on its strength and specificity. The aim of this study is to investigate and compare the physicochemical characteristics of the bond between NCs and ^99mTc and ⁶⁸Ga isotopes. Commercial kits of HSA-based nanocolloid particles (NanoAlbumon^®) were used. For this purpose, we have primarily studied the kinetic orders of NC radiolabelling. Langmuir isotherms and pH effect on radiolabelling were tested and the stability of the radiometal complex was verified through competition reactions carried out in presence of different ligands. The future goal of our research is the development of inexpensive and instant kits, easily labelled with a wide spectrum of diagnostic and therapeutic isotopes, thus facilitating the availability of versatile and multipurpose radiopharmaceuticals.

Keywords: 68Ga; 99mTc; PET (positron emission tomography); SPECT (single-photon emission computed tomography); human serum albumin; nanocolloids; radiopharmaceutical.