Site-specific conjugated antibody-element tags for single-cell ICP-MS

Area of Science:

• Biomolecular analysis
• Analytical chemistry
• Nanotechnology

Background:

• Traditional antibody-elemental tags (AETs) for ICP-MS suffer from structural heterogeneity due to random modification, impacting binding affinity and specificity.
• This heterogeneity limits the analytical performance and sensitivity of ICP-MS-based biomolecule detection.
• A need exists for uniform and stable AETs to improve quantitative bioanalysis.

Purpose of the Study:

• To develop a traceless, site-specific conjugation strategy for creating uniform antibody-elemental tags (AETs).
• To improve the binding affinity, specificity, and analytical performance of AETs for ICP-MS.
• To enable highly sensitive and quantitative single-cell bioanalysis.

Main Methods:

• Developed a traceless, site-specific conjugation strategy attaching single-stranded DNA (ssDNA) to the K248 residue of IgG antibodies.
• Utilized ssDNA as a linker for hybridization with europium (Eu)-loaded MS2 capsid nanoparticles, serving as signal amplifiers.
• Created site-specific AETs (ssAETs) by integrating precise antibody modification with high-capacity MS2 elemental carriers.

Main Results:

• The developed ssAETs exhibited exceptional structural uniformity, stability, and sensitivity.
• Demonstrated superior specificity and quantitative performance using human epidermal growth factor receptor 2 (HER2) as a model.
• Achieved 1.8-fold stronger single-cell signals and labeled 1.5 times more HER2-positive cells compared to randomly conjugated antibodies.

Conclusions:

• The traceless, site-specific ssAET platform offers a versatile and precise approach for bioanalysis.
• This strategy significantly enhances sensitivity and quantitative performance in single-cell analysis using ICP-MS.
• The method preserves native antibody structure and binding activity, overcoming limitations of traditional AETs.