Characterization of 18 F-dipicolylamine (DPA) derivatives in cells infected with influenza virus

Junling Li, Rachael L. Gerlach, Colleen Jonsson, Brian D. Gray, Koon Y. Pak, Chin K. Ng

Research output: Contribution to journalArticle

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Abstract

Objective: Bis(Zn-dipicolylamine (Zn-DPA)) coordination complexes represent a new class of synthetic small molecules that can target anionic phosphatidylserine (PS) in the apoptotic cells with high affinity and specificity. In this study, we labeled Zn-DPA and Cy7-Zn-DPA with different 18 F-prosthetic groups and characterized their uptake in A549 cells infected with influenza A virus from the 2009 pandemic (H1N1pdm). Methods: DPA was labeled with N-succinimidyl 4- 18 F-fluorobenzoate ( 18 F-SFB), 4-nitrophenyl 2- 18 F-fluoropropionate ( 18 F-NFP), 2- 18 F-Fluoroethyl toslyate ( 18 F-FET), and 18 F-aluminum (Al 18 F), respectively. Cy7-DPA was labeled with 18 F-SFB and 18 F-NFP only. The tracers were reconstituted with zinc nitrate before use. Apoptosis in A549 cells was induced by infection with the H1N1pdm virus for 48h. Three μCi of each tracer was added to each well and incubated at 37°C. The effect of different prosthetic groups, different MOI, and incubation time on percent cellular uptake was studied. Cell internalization and efflux was evaluated within 2h of incubation. The competitive binding assay was performed with increasing concentration (10 -12 -10 -5 M) of Zn-DPA or Cy7-Zn-DPA prior to the addition of either 18 F-FB-Zn-DPA or 18 F-FB-Cy7-Zn-DPA into each well. IC 50 values for the two Zn-DPA analogues were estimated by GraphPad Prism 6.0. Results: Among all the four prosthetic groups, the 18 F-SFB method provided the highest conjugation yield for DPA and the highest uptake ratio between the infection cells and the control when both Zn-DPA and Cy7-Zn-DPA were present in the complex. The uptake ratio was similar for 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA. Uptake of 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA was proportional to the degree of apoptosis with a plateau at MOI 3. Uptake of 18 F-FB-Cy7-Zn-DPA also increased over incubation time and reached a plateau at 1h, whereas uptake of 18 F-FB-Zn-DPA did not show any significant change over time. Cell internalization studies showed that more than 70% of 18 F-FB-Zn-DPA remained on the cell surface over a time course of 2hr in the cell media, but over 90% of 18 F-FB-Cy7-Zn-DPA was internalized within 15min of incubation. IC 50 values were estimated to be 1.5±0.3 nM and 26.2±5.1 nM for Zn-DPA and Cy7-Zn-DPA, respectively. Conclusions: 18 F-SFB was the optimal labeling method for Zn-DPA and Cy7-Zn-DPA with respect to radiochemistry and provided complexes with high target-to-background ratios. 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA appeared to have a completely different internalization mechanism, while Zn-DPA showed higher binding affinity than Cy7-Zn-DPA. Based on these favorable characteristics, 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA should be further evaluated as potential imaging agents for viral infection.

Original languageEnglish (US)
Pages (from-to)283-291
Number of pages9
JournalNuclear Medicine and Biology
Volume42
Issue number3
DOIs
StatePublished - Mar 1 2015
Externally publishedYes

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Orthomyxoviridae
2,2'-dipicolylamine
Radiochemistry

All Science Journal Classification (ASJC) codes

  • Molecular Medicine
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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Characterization of 18 F-dipicolylamine (DPA) derivatives in cells infected with influenza virus . / Li, Junling; Gerlach, Rachael L.; Jonsson, Colleen; Gray, Brian D.; Pak, Koon Y.; Ng, Chin K.

In: Nuclear Medicine and Biology, Vol. 42, No. 3, 01.03.2015, p. 283-291.

Research output: Contribution to journalArticle

Li, Junling ; Gerlach, Rachael L. ; Jonsson, Colleen ; Gray, Brian D. ; Pak, Koon Y. ; Ng, Chin K. / Characterization of 18 F-dipicolylamine (DPA) derivatives in cells infected with influenza virus In: Nuclear Medicine and Biology. 2015 ; Vol. 42, No. 3. pp. 283-291.
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title = "Characterization of 18 F-dipicolylamine (DPA) derivatives in cells infected with influenza virus",
abstract = "Objective: Bis(Zn-dipicolylamine (Zn-DPA)) coordination complexes represent a new class of synthetic small molecules that can target anionic phosphatidylserine (PS) in the apoptotic cells with high affinity and specificity. In this study, we labeled Zn-DPA and Cy7-Zn-DPA with different 18 F-prosthetic groups and characterized their uptake in A549 cells infected with influenza A virus from the 2009 pandemic (H1N1pdm). Methods: DPA was labeled with N-succinimidyl 4- 18 F-fluorobenzoate ( 18 F-SFB), 4-nitrophenyl 2- 18 F-fluoropropionate ( 18 F-NFP), 2- 18 F-Fluoroethyl toslyate ( 18 F-FET), and 18 F-aluminum (Al 18 F), respectively. Cy7-DPA was labeled with 18 F-SFB and 18 F-NFP only. The tracers were reconstituted with zinc nitrate before use. Apoptosis in A549 cells was induced by infection with the H1N1pdm virus for 48h. Three μCi of each tracer was added to each well and incubated at 37°C. The effect of different prosthetic groups, different MOI, and incubation time on percent cellular uptake was studied. Cell internalization and efflux was evaluated within 2h of incubation. The competitive binding assay was performed with increasing concentration (10 -12 -10 -5 M) of Zn-DPA or Cy7-Zn-DPA prior to the addition of either 18 F-FB-Zn-DPA or 18 F-FB-Cy7-Zn-DPA into each well. IC 50 values for the two Zn-DPA analogues were estimated by GraphPad Prism 6.0. Results: Among all the four prosthetic groups, the 18 F-SFB method provided the highest conjugation yield for DPA and the highest uptake ratio between the infection cells and the control when both Zn-DPA and Cy7-Zn-DPA were present in the complex. The uptake ratio was similar for 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA. Uptake of 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA was proportional to the degree of apoptosis with a plateau at MOI 3. Uptake of 18 F-FB-Cy7-Zn-DPA also increased over incubation time and reached a plateau at 1h, whereas uptake of 18 F-FB-Zn-DPA did not show any significant change over time. Cell internalization studies showed that more than 70{\%} of 18 F-FB-Zn-DPA remained on the cell surface over a time course of 2hr in the cell media, but over 90{\%} of 18 F-FB-Cy7-Zn-DPA was internalized within 15min of incubation. IC 50 values were estimated to be 1.5±0.3 nM and 26.2±5.1 nM for Zn-DPA and Cy7-Zn-DPA, respectively. Conclusions: 18 F-SFB was the optimal labeling method for Zn-DPA and Cy7-Zn-DPA with respect to radiochemistry and provided complexes with high target-to-background ratios. 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA appeared to have a completely different internalization mechanism, while Zn-DPA showed higher binding affinity than Cy7-Zn-DPA. Based on these favorable characteristics, 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA should be further evaluated as potential imaging agents for viral infection.",
author = "Junling Li and Gerlach, {Rachael L.} and Colleen Jonsson and Gray, {Brian D.} and Pak, {Koon Y.} and Ng, {Chin K.}",
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doi = "10.1016/j.nucmedbio.2014.11.012",
language = "English (US)",
volume = "42",
pages = "283--291",
journal = "Nuclear Medicine and Biology",
issn = "0969-8051",
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TY - JOUR

T1 - Characterization of 18 F-dipicolylamine (DPA) derivatives in cells infected with influenza virus

AU - Li, Junling

AU - Gerlach, Rachael L.

AU - Jonsson, Colleen

AU - Gray, Brian D.

AU - Pak, Koon Y.

AU - Ng, Chin K.

PY - 2015/3/1

Y1 - 2015/3/1

N2 - Objective: Bis(Zn-dipicolylamine (Zn-DPA)) coordination complexes represent a new class of synthetic small molecules that can target anionic phosphatidylserine (PS) in the apoptotic cells with high affinity and specificity. In this study, we labeled Zn-DPA and Cy7-Zn-DPA with different 18 F-prosthetic groups and characterized their uptake in A549 cells infected with influenza A virus from the 2009 pandemic (H1N1pdm). Methods: DPA was labeled with N-succinimidyl 4- 18 F-fluorobenzoate ( 18 F-SFB), 4-nitrophenyl 2- 18 F-fluoropropionate ( 18 F-NFP), 2- 18 F-Fluoroethyl toslyate ( 18 F-FET), and 18 F-aluminum (Al 18 F), respectively. Cy7-DPA was labeled with 18 F-SFB and 18 F-NFP only. The tracers were reconstituted with zinc nitrate before use. Apoptosis in A549 cells was induced by infection with the H1N1pdm virus for 48h. Three μCi of each tracer was added to each well and incubated at 37°C. The effect of different prosthetic groups, different MOI, and incubation time on percent cellular uptake was studied. Cell internalization and efflux was evaluated within 2h of incubation. The competitive binding assay was performed with increasing concentration (10 -12 -10 -5 M) of Zn-DPA or Cy7-Zn-DPA prior to the addition of either 18 F-FB-Zn-DPA or 18 F-FB-Cy7-Zn-DPA into each well. IC 50 values for the two Zn-DPA analogues were estimated by GraphPad Prism 6.0. Results: Among all the four prosthetic groups, the 18 F-SFB method provided the highest conjugation yield for DPA and the highest uptake ratio between the infection cells and the control when both Zn-DPA and Cy7-Zn-DPA were present in the complex. The uptake ratio was similar for 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA. Uptake of 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA was proportional to the degree of apoptosis with a plateau at MOI 3. Uptake of 18 F-FB-Cy7-Zn-DPA also increased over incubation time and reached a plateau at 1h, whereas uptake of 18 F-FB-Zn-DPA did not show any significant change over time. Cell internalization studies showed that more than 70% of 18 F-FB-Zn-DPA remained on the cell surface over a time course of 2hr in the cell media, but over 90% of 18 F-FB-Cy7-Zn-DPA was internalized within 15min of incubation. IC 50 values were estimated to be 1.5±0.3 nM and 26.2±5.1 nM for Zn-DPA and Cy7-Zn-DPA, respectively. Conclusions: 18 F-SFB was the optimal labeling method for Zn-DPA and Cy7-Zn-DPA with respect to radiochemistry and provided complexes with high target-to-background ratios. 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA appeared to have a completely different internalization mechanism, while Zn-DPA showed higher binding affinity than Cy7-Zn-DPA. Based on these favorable characteristics, 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA should be further evaluated as potential imaging agents for viral infection.

AB - Objective: Bis(Zn-dipicolylamine (Zn-DPA)) coordination complexes represent a new class of synthetic small molecules that can target anionic phosphatidylserine (PS) in the apoptotic cells with high affinity and specificity. In this study, we labeled Zn-DPA and Cy7-Zn-DPA with different 18 F-prosthetic groups and characterized their uptake in A549 cells infected with influenza A virus from the 2009 pandemic (H1N1pdm). Methods: DPA was labeled with N-succinimidyl 4- 18 F-fluorobenzoate ( 18 F-SFB), 4-nitrophenyl 2- 18 F-fluoropropionate ( 18 F-NFP), 2- 18 F-Fluoroethyl toslyate ( 18 F-FET), and 18 F-aluminum (Al 18 F), respectively. Cy7-DPA was labeled with 18 F-SFB and 18 F-NFP only. The tracers were reconstituted with zinc nitrate before use. Apoptosis in A549 cells was induced by infection with the H1N1pdm virus for 48h. Three μCi of each tracer was added to each well and incubated at 37°C. The effect of different prosthetic groups, different MOI, and incubation time on percent cellular uptake was studied. Cell internalization and efflux was evaluated within 2h of incubation. The competitive binding assay was performed with increasing concentration (10 -12 -10 -5 M) of Zn-DPA or Cy7-Zn-DPA prior to the addition of either 18 F-FB-Zn-DPA or 18 F-FB-Cy7-Zn-DPA into each well. IC 50 values for the two Zn-DPA analogues were estimated by GraphPad Prism 6.0. Results: Among all the four prosthetic groups, the 18 F-SFB method provided the highest conjugation yield for DPA and the highest uptake ratio between the infection cells and the control when both Zn-DPA and Cy7-Zn-DPA were present in the complex. The uptake ratio was similar for 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA. Uptake of 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA was proportional to the degree of apoptosis with a plateau at MOI 3. Uptake of 18 F-FB-Cy7-Zn-DPA also increased over incubation time and reached a plateau at 1h, whereas uptake of 18 F-FB-Zn-DPA did not show any significant change over time. Cell internalization studies showed that more than 70% of 18 F-FB-Zn-DPA remained on the cell surface over a time course of 2hr in the cell media, but over 90% of 18 F-FB-Cy7-Zn-DPA was internalized within 15min of incubation. IC 50 values were estimated to be 1.5±0.3 nM and 26.2±5.1 nM for Zn-DPA and Cy7-Zn-DPA, respectively. Conclusions: 18 F-SFB was the optimal labeling method for Zn-DPA and Cy7-Zn-DPA with respect to radiochemistry and provided complexes with high target-to-background ratios. 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA appeared to have a completely different internalization mechanism, while Zn-DPA showed higher binding affinity than Cy7-Zn-DPA. Based on these favorable characteristics, 18 F-FB-Zn-DPA and 18 F-FB-Cy7-Zn-DPA should be further evaluated as potential imaging agents for viral infection.

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