Laser-induced breakdown spectroscopy as a readout method for immunocytochemistry with upconversion nanoparticles

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Cancer Diagnostics

Background:

• Immunohistochemistry (IHC) and immunocytochemistry (ICC) are standard for identifying cancerous cells but have limitations in labeling and multiplexing.
• Existing methods necessitate alternative readout techniques for enhanced sensitivity and broader applications.

Purpose of the Study:

• To introduce and validate Laser-induced breakdown spectroscopy (LIBS) as a Tag-LIBS approach for biomarker detection.
• To assess the efficacy of Tag-LIBS in specifically determining the HER2 biomarker in cell samples.

Main Methods:

• Cell pellets were labeled with streptavidin-conjugated upconversion nanoparticles (UCNP) via anti-HER2 and biotinylated antibodies.
• LIBS was employed to detect the elemental signature of yttrium, a component of UCNP, in labeled cell pellets.
• Results were compared with upconversion optical microscopy and luminescence intensity scanning.

Main Results:

• LIBS successfully detected the elemental signature of yttrium, confirming the presence of UCNP.
• The method reliably differentiated between HER2-positive (BT-474) and HER2-negative (MDA-MB-231) cells.
• LIBS demonstrated comparable results to established optical microscopy techniques.

Conclusions:

• Tag-LIBS, utilizing elemental analysis, is a promising alternative readout technique for IHC and ICC.
• This method offers a reliable and sensitive approach for specific biomarker determination, such as HER2.
• LIBS presents a potential advancement in cancer diagnostics and cell analysis.