Reactor production and electrochemical purification of (169)Er: a potential step forward for its utilization in in vivo therapeutic applications.

Abstract

INTRODUCTION:

The aim of the present study was to develop and demonstrate a viable method for the reactor production of (169)Er with acceptable specific activity using moderate flux reactor and its purification from (169)Yb following electrochemical pathway based on mercury-pool cathode to avail (169)Er in radionuclidically pure form essential for its therapeutic use.

METHODS:

Erbium-169 was produced in reactor by neutron bombardment of isotopically enriched (98.2% in (168)Er) erbium target at a thermal neutron flux of ~8×10(13) n.cm(-2).s(-1) for 21 d. A thorough optimization of irradiation parameters including neutron flux, irradiation time and target cooling time was carried out. The influence of different experimental parameters for the quantitative removal (169)Yb from (169)Er was investigated, optimized and based on the results; a two-cycle electrochemical separation procedure was adopted. The suitablility of purified (169)Er for application in radiation synovectomy and bone pain palliation was ascertained by carrying out radiolabeling studies with hydroxypaptite (HA) particles and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraaminomethylene phosphonic acid (DOTMP), respectively.

RESULTS:

Thermal neutron irradiation of 10mg of isotopically enriched (98.2% in (168)Er) erbium target at a flux of ~8×10(13) n.cm(-2).s(-1) for 21 d followed by a two-step electrochemical separation of (169)Yb impurity yielded ~3.7GBq (100mCi) of (169)Er with a specific activity of ~370MBq/mg (10mCi/mg) and radionuclidic purity of >99.99%. The reliability of this approach was amply demonstrated by performing several production batches, where the performance of each batch remained consistent. The utility of the purified (169)Er was demonstrated in the radiolabeling studies with HA particles and DOTMP, wherein both the radiolabeled products were obtained with high radiolabeling yield (>99%).

CONCLUSIONS:

A viable strategy for the batch production and purification of (169)Er, suitable for therapeutic applications, has been developed and demonstrated.

• Authors: Rubel Chakravarty, Sudipta Chakraborty, Viju Chirayil, Ashutosh Dash
• Journal: Nuclear medicine and biology (Nucl Med Biol) Vol. 41 Issue 2 Pg. 163-70 (Feb 2014) ISSN: 1872-9614 [Electronic] United States
• PMID: 24480267 (Publication Type: Journal Article)
• Copyright: Copyright © 2014 Elsevier Inc. All rights reserved.

Chemical References

• Organophosphorus Compounds
• Radioisotopes
• 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetrakis(methylenephosphonic acid)
• Erbium
• Mercury
• Ytterbium

Topics

• Electrochemistry (methods)
• Erbium (chemistry, therapeutic use)
• Hydrogen-Ion Concentration
• Kinetics
• Mercury (isolation & purification)
• Neutrons
• Organophosphorus Compounds (chemistry)
• Radiochemistry (methods)
• Radioisotopes (chemistry, therapeutic use)
• Ytterbium (isolation & purification)