Cell assay using a two-photon-excited europium chelate

Area of Science:

• Biochemistry
• Cell Biology
• Biophotonics

Background:

• Epidermal growth factor receptor (EGFR) is a key target in cancer therapy.
• Accurate cell surface protein detection is crucial for cancer research.
• Limitations exist in current immunolabeling and imaging techniques.

Purpose of the Study:

• To apply two-photon excitation of europium chelates for EGFR immunolabeling.
• To evaluate the efficacy and sensitivity of this novel labeling method.
• To image EGFR on A431 cancer cells using multiphoton microscopy.

Main Methods:

• Conjugating europium chelates to antibodies specific for EGFR.
• Labeling A431 (human epidermoid carcinoma) cells with the conjugate.
• Utilizing a multiphoton microscope with scanning laser excitation and non-scanning CCD detection.
• Assessing photobleaching and autofluorescence properties of the europium labels.

Main Results:

• Europium chelates were successfully excited by two-photon infrared light, emitting visible light.
• The labels exhibited minimal photobleaching (<1% over 20 minutes).
• Autofluorescence was low (<1% of the signal from labeled cells).
• The detection limit was superior to 100 zeptomoles.

Conclusions:

• Two-photon excitation of europium chelates is a viable method for EGFR immunolabeling.
• This technique offers high sensitivity and stability for cell surface protein imaging.
• The low photobleaching and autofluorescence enhance imaging quality in cancer cell studies.