Structural characterization of site-modified nanocapsid with monodispersed gold clusters

Area of Science:

• Biotechnology
• Nanotechnology
• Virology

Background:

• Hepatitis E virus-like particles form noninfectious nanocapsids resistant to mucosal conditions.
• Engineered nanocapsids previously demonstrated specific binding and entry into breast cancer cells, with successful tumor targeting in animal models.

Purpose of the Study:

• To modify nanocapsid surfaces with monolayer protected gold nanoclusters (AuNCs) for enhanced cancer targeting.
• To investigate conjugation methods and characterize AuNC-bound nanocapsid constructs.

Main Methods:

• Solvent-exposed cysteines were introduced on nanocapsid surfaces for AuNC conjugation.
• Two conjugation strategies were employed: direct ligand exchange and maleimide-thiol conjugation using Au102_C6MI.
• Cryo-electron microscopy (cryo-EM) and single particle reconstruction were used to visualize and localize AuNCs on nanocapsids.

Main Results:

• Au102_C6MI demonstrated more efficient binding to nanocapsids compared to Au102.
• AuNC-bound nanocapsids were successfully imaged, revealing a ring-shaped density of AuNCs at the 5-fold symmetry center.
• Cryo-EM and rigid modeling confirmed the precise localization of AuNCs on the nanocapsid surface.

Conclusions:

• The study successfully conjugated AuNCs to Hepatitis E virus-like nanocapsids, creating novel constructs for potential biomedical applications.
• The findings provide a foundation for developing targeted cancer therapies and advanced imaging agents using AuNC-functionalized nanocapsids.