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Two-photon fluorescent probe for cadmium imaging in cells.
Yongyou Liu1, Xiaohu Dong, Jian Sun
1Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan, 430072, P. R. China.
The Analyst
|March 6, 2012
Summary
A new fluorescent probe, TPCd, detects cadmium ions (Cd2+) with high sensitivity and selectivity using two-photon excitation. This probe is non-toxic and effective for imaging cadmium uptake in living cells.
Area of Science:
- Chemical Sensing
- Fluorescent Probes
- Biomedical Imaging
Background:
- Cadmium (Cd2+) is a toxic heavy metal with significant health implications.
- Development of sensitive and selective probes for Cd2+ detection is crucial for environmental and biological monitoring.
- Two-photon excitation (TPE) offers advantages for deep tissue imaging and reduced phototoxicity compared to one-photon excitation (OPE).
Purpose of the Study:
- To design and synthesize a novel two-photon excited fluorescent probe (TPCd) for sensitive and selective detection of cadmium ions (Cd2+).
- To evaluate the photophysical properties, sensing mechanism, and performance of the TPCd probe for Cd2+.
- To demonstrate the application of the TPCd probe for imaging intracellular Cd2+ uptake in living cells using two-photon microscopy.
Main Methods:
- Synthesis of a novel fluorescent probe (TPCd) based on a prodan derivative and an o-phenylenediamine derivative.
- Investigation of photophysical properties including fluorescence enhancement upon Cd2+ binding via a photoinduced electron transfer (PET) mechanism.
- Characterization of probe-Cd2+ complex stoichiometry, dissociation constant (Kd), and detection limit.
- Evaluation of probe selectivity, pH independence, and cytotoxicity.
- Application of the probe for intracellular Cd2+ detection in HepG2 cells using two-photon microscopy.
Main Results:
- The TPCd probe exhibited favorable photophysical properties and good water-solubility.
- Upon Cd2+ binding, fluorescence intensity increased up to 15-fold (OPE) and 27-fold (TPE), with a high two-photon action cross-section (109 GM).
- The probe demonstrated a 1:1 binding stoichiometry with Cd2+, a detection limit of 0.04 μM, and high selectivity.
- TPCd was pH-independent in the biological range and non-toxic to living cells.
- Successful detection of intracellular Cd2+ uptake in HepG2 cells was achieved using two-photon microscopy.
Conclusions:
- The novel TPCd probe is a highly sensitive and selective tool for detecting cadmium ions.
- The probe's excellent photophysical properties and biocompatibility make it suitable for two-photon imaging applications.
- TPCd enables effective visualization of cadmium ion dynamics within living cells, offering potential for toxicological studies.
