TY - JOUR
T1 - Near-infrared fluorescence lifetime pH-sensitive probes
AU - Berezin, Mikhail Y.
AU - Guo, Kevin
AU - Akers, Walter
AU - Northdurft, Ralph E.
AU - Culver, Joseph P.
AU - Teng, Bao
AU - Vasalatiy, Olga
AU - Barbacow, Kyle
AU - Gandjbakhche, Amir
AU - Griffiths, Gary L.
AU - Achilefu, Samuel
N1 - Funding Information:
This work was supported primarily by the National Institute of Biomedical Imaging and Bioengineering under grant No. RO1EB007276, and in part by other funds by the National Institutes of Health under grants No. R01 EB008111, No. R01 EB001430, No. R01 EB008458, No. R01 CA109754, No. R33 CA123537, and No. R21 CA149814 as well as the the NIH Roadmap for Medical Research as funding source for the IPDC, and the Intramural Research Program of Eunice Shriver NICHD.
PY - 2011/4/20
Y1 - 2011/4/20
N2 - We report what we believe to be the first near-infrared pH-sensitive fluorescence lifetime molecular probe suitable for biological applications in physiological range. Specifically, we modified a known fluorophore skeleton, hexamethylindotricarbocyanine, with a tertiary amine functionality that was electronically coupled to the fluorophore, to generate a pH-sensitive probe. The pKa of the probe depended critically on the location of the amine. Peripheral substitution at the 5-position of the indole ring resulted in a compound with pKa ∼ 4.9 as determined by emission spectroscopy. In contrast, substitution at the meso-position shifted the pKa to 5.5. The resulting compound, LS482, demonstrated steady-state and fluorescence-lifetime pH-sensitivity. This sensitivity stemmed from distinct lifetimes for protonated (∼1.16 ns in acidic DMSO) and deprotonated (∼1.4 ns in basic DMSO) components. The suitability of the fluorescent dyes for biological applications was demonstrated with a fluorescencelifetime tomography system. The ability to interrogate cellular processes and subsequently translate the findings in living organisms further augments the potential of these lifetime-based pH probes.
AB - We report what we believe to be the first near-infrared pH-sensitive fluorescence lifetime molecular probe suitable for biological applications in physiological range. Specifically, we modified a known fluorophore skeleton, hexamethylindotricarbocyanine, with a tertiary amine functionality that was electronically coupled to the fluorophore, to generate a pH-sensitive probe. The pKa of the probe depended critically on the location of the amine. Peripheral substitution at the 5-position of the indole ring resulted in a compound with pKa ∼ 4.9 as determined by emission spectroscopy. In contrast, substitution at the meso-position shifted the pKa to 5.5. The resulting compound, LS482, demonstrated steady-state and fluorescence-lifetime pH-sensitivity. This sensitivity stemmed from distinct lifetimes for protonated (∼1.16 ns in acidic DMSO) and deprotonated (∼1.4 ns in basic DMSO) components. The suitability of the fluorescent dyes for biological applications was demonstrated with a fluorescencelifetime tomography system. The ability to interrogate cellular processes and subsequently translate the findings in living organisms further augments the potential of these lifetime-based pH probes.
UR - http://www.scopus.com/inward/record.url?scp=79959762117&partnerID=8YFLogxK
U2 - 10.1016/j.bpj.2011.02.050
DO - 10.1016/j.bpj.2011.02.050
M3 - Article
C2 - 21504743
AN - SCOPUS:79959762117
SN - 0006-3495
VL - 100
SP - 2063
EP - 2072
JO - Biophysical Journal
JF - Biophysical Journal
IS - 8
ER -