Porphyrin FRET acceptors for apoptosis induction and monitoring.
Photodynamic therapy (PDT) stands to benefit from improved approaches to real-time treatment monitoring. One method is to use activatable photosensitizers that can both induce cell death (via singlet oxygen) and monitor it (via caspase detection). Here, we report porphyrins as caspase-responsive Forster Resonance Energy Transfer (FRET) acceptors to organic fluorophore donors. Compared to porphyrin FRET donor constructs, singlet oxygen generation was unquenched prior to caspase activation, resulting in more efficient photosensitization in HT-29 cancer cells. The donor 5-Carboxy-X-Rhodamine (Rox) formed a robust FRET pair with the pyropheophorbide (Pyro) acceptor. The large dynamic range of the construct enabled ratiometric imaging (with Rox excitation) of caspase activation in live, single cells following induction of cell death (with Pyro excitation) using a single agent. Quantitative, unquenched activatable photosensitizers (QUaPS) hold potential for new feedback-oriented PDT approaches.
Department of Biomedical Engineering, University at Buffalo, State University of New York, Buffalo, New York 14260, USA
Jonathan F
JF
Lovell
Michael W
MW
Chan
Qiaochu
Q
Qi
Juan
J
Chen
Gang
G
Zheng
D017209:Apoptosis; D020169:Caspases / Q000737:chemistry / Q000378:metabolism; D003584:Cytological Techniques; D031541:Fluorescence Resonance Energy Transfer; D019073:HT29 Cells; D006801:Humans; D018613:Microscopy, Confocal; D015394:Molecular Structure; D011166:Porphyrins / Q000737:chemistry*; D026082:Singlet Oxygen / Q000032:analysis / Q000737:chemistry
D011166:Porphyrins; D026082:Singlet Oxygen; D020169:Caspases