MQA-P

MQA-P is a multifunctional near-infrared (NIR) fluorescent probe for simultaneously detecting ONOO-, viscosity, and polarity within mitochondria. MQA-P exhibits a remarkable turn-on response to ONOO- (λem=645 nm) and is highly sensitive to viscosity/polarity in the NIR channel with λem>704 nm. MQA-P exhibits excited-state intramolecular charge transfer (ESICT) feature that is highly polarity-sensitive by engineering N,N-dimethylamino as the electron donor and a quinoline cationic unit as the electron acceptor. MQA-P is used for ferroptosis or cancer diagnosis in vitro and in vivo via dual-channel images.

Guidelines (Following is our recommended protocol. This protocol only provides a guideline, and should be modified according to your specific needs).
1. MQA-P is dissolved in dimethyl sulfoxide (DMSO) to prepare a stock solution (1.0 mM).
2. For imaging of ONOO^- in live cells.
HeLa cells are incubated with MQA-P (5 μM) for 30 min as control; pretreated with SIN-1 for 30 min and then incubated with MQA-P (5 μM) for another 30 min. The fluorescence images are obtained on a confocal laser scanning microscope with a green channel (λ_ex= 405nm, λ_em= 550-670 nm).
3. For imaging of viscosity in live cells.
HeLa cells were incubated with MQA-P (5 μM) for 30 min as control; pretreated with Monensin for 30 min and then incubated with MQA-P (5 μM) for another 30min. The fluorescence images are obtained on a confocal laser scanning microscope with a red channel (λ_ex= 561 nm, λ_em= 680-750 nm).
4. For dual-channel imaging of ONOO^-, viscosity and polarity during ferroptosis.
HeLa cells are incubated with MQA-P (5 μM) for 30 min as control; pretreated with Erastin for 30 min and then incubated with MQA-P (5 μM) for another 30 min. The fluorescence images are obtained on a confocal laser scanning microscope with a green channel (λ_ex= 405nm, λ_em= 550-670 nm) for ONOO^- and a red channel (λ_ex= 561 nm, λ_em= 680-750 nm) for viscosity and polarity^[1].

Guidelines (Following is our recommended protocol. This protocol only provides a guideline, and should be modified according to your specific needs).
1. For tissue slices imaging, the normal organs (including heart, liver, spleen, lung, and kidney) and tumor are isolated from the mice, then sectioned as 5 μm thicknesses, respectively.
2. These slices are incubated with MQA-P (20 μM) for 30 min, then washed with PBS (pH 7.4) three times, and finally subjected to in vivo imaging using a confocal laser scanning microscope with a green channel (λ_ex=405nm, λ_em=550-670 nm) for ONOO^- and a red channel(λ_ex=561 nm, λ_em=680-750 nm) for viscosity and polarity, respectively^[1].

References:
[1]. Li Fan, et al. Multifunctional Fluorescent Probe for Simultaneous Detection of ONOO-, Viscosity, and Polarity and Its Application in Ferroptosis and Cancer Models. Anal Chem. 2023 Apr 4;95(13):5780-5787.