Eleven tungsten atom cluster labels: high-resolution, site-specific probes for electron microscopy

Area of Science:

• Inorganic Chemistry
• Materials Science
• Bioconjugation Chemistry

Background:

• Tungstate clusters are nanoscale materials with unique properties.
• Developing site-specific labeling reagents is crucial for advanced biomolecular imaging.
• Existing electron microscopy (EM) markers have limitations in resolution and stability.

Purpose of the Study:

• To synthesize novel tungstate (W11) cluster derivatives for biomolecule labeling.
• To create electron-dense, beam-resistant markers for high-resolution EM.
• To demonstrate site-specific covalent attachment to proteins.

Main Methods:

• Synthesis of two W11 cluster derivatives: W11-sulfonyl chloride and W11-thiosulfonate.
• Characterization of the W11 cluster size (1.0 nm), electron density, and visibility in electron microscopes.
• Demonstration of reactivity with amine, sulfhydryl, and thiol groups for covalent labeling.
• Application of the W11 labels to the protein albumin.

Main Results:

• Successful synthesis of W11-sulfonyl chloride and W11-thiosulfonate derivatives.
• W11 clusters are 1.0 nm, electron-dense, and EM-visible.
• The derivatives enable site-specific covalent attachment to biomolecules.
• The W11 labels exhibit beam resistance and higher EM resolution compared to conventional markers.
• Successful labeling of albumin protein was achieved.

Conclusions:

• Novel W11 tungstate cluster derivatives serve as advanced EM labels.
• These labels facilitate site-specific covalent conjugation to biomolecules.
• The W11 markers provide superior resolution and stability for electron microscopy applications.