Radiolabeled Zn-DPA as a potential infection imaging agent

UMMS Affiliation

Department of Radiology; Department of Pathology

Publication Date


Document Type



Animals; Biotinylation; Chelating Agents; Fluorescent Dyes; Heterocyclic Compounds, 1-Ring; Inflammation; Isotope Labeling; Lipopolysaccharides; Mice; Multimodal Imaging; Nanoparticles; Organometallic Compounds; Picolinic Acids; Positron-Emission Tomography; Streptavidin; Streptococcal Infections; Streptococcus pyogenes; Tomography, X-Ray Computed


Bacterial Infections and Mycoses | Diagnosis | Medical Pathology | Pathology | Radiology


INTRODUCTION: A zinc-dipicolylamine analog (Zn-DPA) conjugated with a fluorophore (PSVue(R)794) has been shown to image bacterial infections in mice. However, radiolabeled Zn-DPA has not previously been considered for nuclear imaging of infection.

METHODS: Both 111In-labeled DOTA-biotin and Zn-DPA-biotin were combined using streptavidin (SA) as a noncovalent linker. Mice injected intramuscularly with Streptococcus pyogenes (infection model) or with lipopolysaccharide (LPS) (inflammation model) were coinjected intravenously with 6 mug of DPA as PSVue794 and as 111In-DOTA-biotin/SA/biotin-Zn-DPA. Periodic fluorescent and SPECT (single photon emission computed tomography)/CT (computed tomography) images were acquired, and biodistributions were obtained at 22 h.

RESULTS: Histological examination confirmed the validity of both the infection and inflammation animal models. Both the whole-body optical and nuclear images showed obvious accumulations in the target thigh in both models at all time points. At 22 h, the average target thigh accumulation of 111In was 1.66%ID/g (S.D. 0.15) in the infection mice compared to 0.58%ID/g (S.D. 0.07) in the inflammation mice (P < .01), and the 111In target/normal thigh ratio was 2.8 fold higher in the infection animals compared to the inflammation animals.

CONCLUSIONS: These preliminary results show that Zn-DPA within streptavidin targets S. pyogenes-infected mice similarly to its free fluorescent analogue. The significantly higher accumulation in the live bacterial infection thigh compared to that of the LPS-induced inflammation thigh suggests that Zn-DPA may be a promising imaging agent to distinguish between bacterial infections and sterile inflammations.


Zn-DPA, Streptavidin, Bacterial infection, Sterile inflammation, Imaging agent

DOI of Published Version



Nucl Med Biol. 2012 Jul;39(5):709-14. doi: 10.1016/j.nucmedbio.2011.12.006. Epub 2012 Feb 10. Link to article on publisher's site.

Journal/Book/Conference Title

Nuclear medicine and biology

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Link to Article in PubMed

PubMed ID