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Updated: Jun 2, 2026
Radiosynthesis, Quality Control, and Small Animal Positron Emission Tomography Imaging of 68Ga-Labelled Nano Molecules
Published on: October 4, 2024
Development of 68Ga-labeled mannosylated human serum albumin (MSA) as a lymph node imaging agent for positron
Jae Yeon Choi1, Jae Min Jeong, Byong Chul Yoo
1Department of Nuclear Medicine, Institute of Radiation Medicine, Seoul National University College of Medicine, Seoul, South Korea.
Introduction:
Although many sentinel lymph node (SLN) imaging agents labeled with (99m)Tc have been developed, no positron-emitting agent has been specifically designed for SLN imaging. Furthermore, the development of the beta probe and the requirement for better image resolution have increased the need for a positron-emitting SLN imaging agent. Here, we describe the development of a novel positron-emitting SLN imaging agent labeled with (68)Ga.
Methods:
A mannosylated human serum albumin (MSA) was synthesized by conjugating α-d-mannopyranosylphenyl isothiocyanate to human serum albumin in sodium carbonate buffer (pH 9.5), and then 2-(p-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid was conjugated to synthesize NOTA-MSA. Numbers of mannose and NOTA units conjugated in NOTA-MSA were determined by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. NOTA-MSA was labeled with (68)Ga at room temperature. The stability of (68)Ga-NOTA-MSA was checked in labeling medium at room temperature and in human serum at 37°C. Biodistribution in normal ICR mice was investigated after tail vein injection, and micro-positron emission tomography (PET) images were obtained after injecting (68)Ga-NOTA-MSA into a tail vein or a footpad.
Results:
The numbers of conjugated α-d-mannopyranosylphenyl isothiocyanate and 2-(p-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid units in NOTA-MSA were 10.6 and 6.6, respectively. The labeling efficiency of (68)Ga-NOTA-MSA was greater than 99% at room temperature, and its stability was greater than 99% at 4 h. Biodistribution and micro-PET studies of (68)Ga-NOTA-MSA showed high liver and spleen uptakes after intravenous injection. (68)Ga-NOTA-MSA injected into a footpad rapidly migrated to the lymph node.
Conclusions:
(68)Ga-NOTA-MSA was successfully developed as a novel SLN imaging agent for PET. NOTA-MSA is easily labeled at high efficiency, and subcutaneously administered (68)Ga-NOTA-MSA was found to migrate rapidly to the lymph node.
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