A mitochondrial-targeted two-photon probe for zinc ion

Area of Science:

• Biochemistry
• Neuroscience
• Chemical Biology

Background:

• Mitochondrial zinc ions ([Zn2+]m) play crucial roles in cellular functions.
• Accurate detection of [Zn2+]m is essential for understanding neurological processes.
• Existing probes may lack specificity or sensitivity for in vivo applications.

Purpose of the Study:

• To develop and characterize a novel two-photon probe for sensitive and specific detection of mitochondrial zinc ions.
• To validate the probe's performance in biological samples under physiological conditions.

Main Methods:

• Synthesis and characterization of the two-photon probe SZn-Mito.
• In vitro evaluation of probe's fluorescence response to Zn2+, including sensitivity (Kd(TP)) and pH stability.
• Application of the probe in rat hippocampal slices using two-photon microscopy for deep-tissue imaging.

Main Results:

• The SZn-Mito probe exhibited a 7-fold fluorescence enhancement upon binding to Zn2+.
• The probe demonstrated high sensitivity with a dissociation constant (Kd(TP)) of 3.1 ± 0.1 nM.
• SZn-Mito showed pH insensitivity within the biologically relevant range and specific detection of [Zn2+]m without interference from other metal ions.
• Successful imaging of [Zn2+]m in rat hippocampal slices at depths of 100–200 μm was achieved.

Conclusions:

• SZn-Mito is a highly sensitive and selective two-photon probe for quantifying mitochondrial zinc ions.
• The probe's properties enable deep-tissue imaging of [Zn2+]m in complex biological systems.
• This tool facilitates further investigation into the role of mitochondrial zinc in neuronal function and disease.