A simplified one-pot automated synthesis of [18F]FHBG for imaging reporter gene expression.
BACKGROUND
9-(4-[F]fluoro-3-hydroxymethylbutyl) guanine ([F]FHBG) has been used as a reporter probe to image the expression of the herpes simplex virus type 1 thymidine kinase (TK) reporter gene in living organisms with positron emission tomography (PET). However, the routine production of [F]FHBG presents many challenging laboratory requirements.


OBJECTIVE
To develop a simple one-pot fully-automated synthesis procedure of [F]FHBG amenable for its routine use in reporter gene expression PET imaging studies.


METHODS
A TRACERlab FXF-N synthesizer was substantially modified and adapted to the synthesis of [F]FHBG through the two-step one-pot procedure. After the fluorination reaction of the tosylate precursor and the hydrolysis of the intermediate product in the same reaction vessel, the final product was purified by Sep-Pak cartridges instead of the high performance liquid chromatography system.


RESULTS
The fully automated synthesis of [F]FHBG with Sep-Pak purification was performed within a short synthesis time. The decay-uncorrected radiochemical yield of [F]FHBG was 8-14% (n=10), the radiochemical purity was more than 99%, and the entire synthesis time was less than 40 min. In addition, the PET image of theTK-transfected nude mice model indicated a much higher uptake of [F]FHBG in the TK-transfected tumor region than in the control tumor region.


CONCLUSIONS
The automated synthesis of [F]FHBG is very easy to carry out using one-pot reactions combined with Sep-Pak purification. The synthetic [F]FHBG can be used for PET imaging and monitoring of in vivo herpes simplex virus type 1 TK gene expression.
Tang
Ganghua
G
Department of Nuclear Medicine, PET-CT Center, The First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China. gtang0224@yahoo.com.cn
Tang
Xiaolan
X
Li
Hongsheng
H
Wang
Mingfang
M
Li
Baoyuan
B
Liang
Mingquan
M
Wu
Hubing
H
Wang
Quanshi
Q
D000818:Animals; D001331:Automation; D002625:Chemistry, Organic / Q000379:methods*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003952:Diagnostic Imaging / Q000379:methods; D005786:Gene Expression Regulation; D017930:Genes, Reporter; D006147:Guanine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D049268:Positron-Emission Tomography / Q000379:methods*; D019275:Radiopharmaceuticals / Q000138:chemical synthesis*; D018139:Simplexvirus / Q000201:enzymology*; D013937:Thymidine Kinase / Q000235:genetics*
C113308:9-(4-fluoro-3-hydroxymethylbutyl)guanine; D019275:Radiopharmaceuticals; D006147:Guanine; D013937:Thymidine Kinase