High-throughput radio-TLC analysis

Jia Wang; Alejandra Rios; Ksenia Lisova; Roger Slavik; Arion F Chatziioannou; R Michael van Dam

doi:10.1016/j.nucmedbio.2019.12.003

High-throughput radio-TLC analysis

Nucl Med Biol. 2020 Mar-Apr:82-83:41-48. doi: 10.1016/j.nucmedbio.2019.12.003. Epub 2019 Dec 17.

Authors

Jia Wang¹, Alejandra Rios², Ksenia Lisova², Roger Slavik³, Arion F Chatziioannou⁴, R Michael van Dam⁵

Affiliations

¹ Crump Institute for Molecular Imaging, University of California Los Angeles, Los Angeles, CA 90095, USA; Department of Bioengineering, University of California Los Angeles, Los Angeles, CA 90095, USA.
² Crump Institute for Molecular Imaging, University of California Los Angeles, Los Angeles, CA 90095, USA; Physics in Biology and Medicine Interdepartmental Graduate Program, University of California Los Angeles, Los Angeles, CA 90095, USA.
³ Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA; Ahmanson Translational Imaging Division, University of California Los Angeles, Los Angeles, CA 90095, USA.
⁴ Crump Institute for Molecular Imaging, University of California Los Angeles, Los Angeles, CA 90095, USA; Physics in Biology and Medicine Interdepartmental Graduate Program, University of California Los Angeles, Los Angeles, CA 90095, USA; Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA.
⁵ Crump Institute for Molecular Imaging, University of California Los Angeles, Los Angeles, CA 90095, USA; Department of Bioengineering, University of California Los Angeles, Los Angeles, CA 90095, USA; Physics in Biology and Medicine Interdepartmental Graduate Program, University of California Los Angeles, Los Angeles, CA 90095, USA; Department of Molecular & Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA 90095, USA. Electronic address: mvandam@mednet.ucla.edu.

Abstract

Introduction: Radio thin layer chromatography (radio-TLC) is commonly used to analyze purity of radiopharmaceuticals or to determine the reaction conversion when optimizing radiosynthesis processes. In applications where there are few radioactive species, radio-TLC is preferred over radio-high-performance liquid chromatography due to its simplicity and relatively quick analysis time. However, with current radio-TLC methods, it remains cumbersome to analyze a large number of samples during reaction optimization. In a couple of studies, Cerenkov luminescence imaging (CLI) has been used for reading radio-TLC plates spotted with a variety of isotopes. We show that this approach can be extended to develop a high-throughput approach for radio-TLC analysis of many samples.

Methods: The high-throughput radio-TLC analysis was carried out by performing parallel development of multiple radioactive samples spotted on a single TLC plate, followed by simultaneous readout of the separated samples using Cerenkov imaging. Using custom-written MATLAB software, images were processed and regions of interest (ROIs) were drawn to enclose the radioactive regions/spots. For each sample, the proportion of integrated signal in each ROI was computed. Various crude samples of [¹⁸F]fallypride, [¹⁸F]FET and [¹⁷⁷Lu]Lu-PSMA-617 were prepared for demonstration of this new method.

Results: Benefiting from a parallel developing process and high resolution of CLI-based readout, total analysis time for eight [¹⁸F]fallypride samples was 7.5 min (2.5 min for parallel developing, 5 min for parallel readout), which was significantly shorter than the 48 min needed using conventional approaches (24 min for sequential developing, 24 min for sequential readout on a radio-TLC scanner). The greater separation resolution of CLI enabled the discovery of a low-abundance side product from a crude [¹⁸F]FET sample that was not discernable using the radio-TLC scanner. Using the CLI-based readout method, we also observed that high labeling efficiency (99%) of [¹⁷⁷Lu]Lu-PSMA-617 can be achieved in just 10 min, rather than the typical 30 min timeframe used.

Conclusions: Cerenkov imaging in combination with parallel developing of multiple samples on a single TLC plate proved to be a practical method for rapid, high-throughput radio-TLC analysis.

Keywords: High-throughput analysis; Quality control testing; Radiochemical purity; Radiopharmaceutical analysis; Radiosynthesis optimization; Thin-layer chromatography.

High-throughput radio-TLC analysis

Authors

Affiliations

Abstract

Publication types

MeSH terms

Grants and funding