TY - JOUR
T1 - Acidic pH-Activatable Visible to Near-Infrared Switchable Ratiometric Fluorescent Probe for Live-Cell Lysosome Targeted Imaging
AU - Mukherjee, Ayan
AU - Saha, Pranab Chandra
AU - Das, Rabi Sankar
AU - Bera, Tapas
AU - Guha, Samit
N1 - Publisher Copyright:
© 2021 American Chemical Society.
PY - 2021/6/25
Y1 - 2021/6/25
N2 - Here, we have designed and synthesized acidic pH-activatable visible to NIR switchable ratiometric pH-sensitive fluorescent dye. The design consists of a cell-permeable organic probe containing a lysosome targeting morpholine functionality and an acidic pH-activatable oxazolidine moiety. The visible closed oxazolidine form (λabs 418 nm) can be switched to the highly conjugated NIR Cy-7 form (λabs 780 nm) through ring opening of the oxazolidine moiety at acidic pH. This switching of the ratiometric fluorescent probe is highly reversible and can be controlled by pH. NMR, UV/vis, and fluorescence spectroscopies allowed monitoring of pH switching behavior of the probe. This bioresponsive in situ acidic organelle activatable fluorophore showed reversible pH-switchable ratiometric optical properties, high photostability, huge bathochromic emission shift of 320 nm from basic to acidic pH, off-to-on narrow NIR absorption and emission bands with enhanced molar extinction coefficient at lysosomal pH, good quantum yield, low cytotoxicity, and targeted imaging ability of live cell lysosomes with ideal pKa. The report demonstrated ratiometric imaging with improved specificity of the acidic lysosome while minimizing signals at the NIR region from nontargeted neutral or basic organelles in human carcinoma HeLa and A549 as well as rat healthy H9c2(2-1) live cells, which is monitored by confocal laser scanning microscopy.
AB - Here, we have designed and synthesized acidic pH-activatable visible to NIR switchable ratiometric pH-sensitive fluorescent dye. The design consists of a cell-permeable organic probe containing a lysosome targeting morpholine functionality and an acidic pH-activatable oxazolidine moiety. The visible closed oxazolidine form (λabs 418 nm) can be switched to the highly conjugated NIR Cy-7 form (λabs 780 nm) through ring opening of the oxazolidine moiety at acidic pH. This switching of the ratiometric fluorescent probe is highly reversible and can be controlled by pH. NMR, UV/vis, and fluorescence spectroscopies allowed monitoring of pH switching behavior of the probe. This bioresponsive in situ acidic organelle activatable fluorophore showed reversible pH-switchable ratiometric optical properties, high photostability, huge bathochromic emission shift of 320 nm from basic to acidic pH, off-to-on narrow NIR absorption and emission bands with enhanced molar extinction coefficient at lysosomal pH, good quantum yield, low cytotoxicity, and targeted imaging ability of live cell lysosomes with ideal pKa. The report demonstrated ratiometric imaging with improved specificity of the acidic lysosome while minimizing signals at the NIR region from nontargeted neutral or basic organelles in human carcinoma HeLa and A549 as well as rat healthy H9c2(2-1) live cells, which is monitored by confocal laser scanning microscopy.
KW - cyanine dye
KW - live-cell imaging
KW - lysosome targeting
KW - pH switching
KW - ratiometric probe
UR - http://www.scopus.com/inward/record.url?scp=85108993265&partnerID=8YFLogxK
U2 - 10.1021/acssensors.1c00961
DO - 10.1021/acssensors.1c00961
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C2 - 34125510
AN - SCOPUS:85108993265
SN - 2379-3694
VL - 6
SP - 2141
EP - 2146
JO - ACS Sensors
JF - ACS Sensors
IS - 6
ER -