Phosphatidylserine (PS), an anionic phospholipid, present in the inner plasma membrane leaflet under normal conditions is translocated to the outside at the onset of cell death. Hence, PS has been identified as a cell death marker and is a frequent target for molecular imaging. The most common imaging agents for PS are radio-labeled and fluorescently tagged annexin V, a protein with nanomolar affinity towards PS. The major drawback of using annexin V for in vivo sensing is high background signals from unbound annexin V. We have strategically modified annexin V to a luminescent lanthanide bound form that remains quenched in the absence of PS and 'turns-on' specifically in its presence. The sensors have the advantage of emission in the visible to near-infrared depending on the lanthanide used and have been tested for in vitro specificity in the presence of different phospholipid vesicles. Data validating the proof-of-concept of using 'lanthano-proteins' for PS detection along with in vitro studies will be presented.

Smart "lanthano-proteins" for phosphatidylserine sensing

245th National Meeting (2013)

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