Physical Changes of Biomacromolecules upon Covalent Surface Immobilization

Area of Science:

• Biomaterials Science
• Nanotechnology
• Surface Chemistry

Background:

• Immobilization of biomacromolecules is crucial for analysis but can alter their structure.
• Understanding how immobilization affects particle morphology is essential for accurate characterization.

Purpose of the Study:

• To investigate the influence of different surface chemistries on the deformation of exosomes and viral particles during immobilization.
• To quantify morphological changes using atomic force microscopy (AFM) and correlate them with surface chemistry.

Main Methods:

• Immobilized exosomes (HEK-293, MDA-MB-231) and viruses (SuHV, XmuLV, PPV) using NHS/EDC and PLL/GA chemistries.
• Quantified particle deformation via height-to-diameter (H/D) ratios from AFM images.
• Utilized dynamic light scattering (DLS) and transmission electron microscopy (TEM) for complementary analysis.

Main Results:

• NHS/EDC chemistry induced greater particle flattening (lower H/D ratios) compared to PLL/GA across all biomacromolecules.
• Softer exosomes exhibited more flattening than rigid viruses.
• Tumor-derived exosomes showed greater flattening than non-tumor-derived exosomes.
• Enveloped viruses flattened with NHS/EDC, while nonenveloped PPV showed aggregation.

Conclusions:

• Surface chemistry critically affects biomacromolecule deformation during immobilization.
• NHS/EDC is more prone to causing flattening than PLL/GA.
• Findings guide the selection of immobilization chemistries for nanoscale biointerface applications, diagnostics, and biosensing.