Probing the adjustments of macromolecules during their surface adsorption

Area of Science:

• Polymer science
• Surface chemistry
• Biomaterials science

Background:

• Thiol-terminated polymers like PMPC-SH, PNIPAM-SH, and PtBA-SH are crucial for surface modification.
• Quartz crystal microbalance with dissipation (QCM-D) and surface plasmon resonance (SPR) are key techniques for monitoring surface events.
• Understanding protein adsorption on polymer brushes is vital for biomaterial development.

Purpose of the Study:

• To synthesize and graft thiol-terminated polymers onto sensor chips.
• To monitor polymer grafting and protein adsorption using QCM-D and SPR.
• To investigate protein conformation changes and adsorption states on polymer brushes.

Main Methods:

• Synthesis of thiol-terminated polymers (PMPC-SH, PNIPAM-SH, PtBA-SH).
• Grafting polymers onto gold-coated QCM-D and SPR sensor chips to form polymer brushes.
• In situ monitoring of grafting and protein adsorption using QCM-D and SPR.
• Analysis of QCM-D data (frequency, dissipation factor, ∂D/∂f) and SPR measurements.

Main Results:

• Successful grafting of polymer brushes was confirmed.
• QCM-D and SPR techniques distinguished different stages of polymer grafting and protein adsorption.
• Bovine serum albumin (BSA) adsorption shifted from a weakly adsorbed native state to a strongly immobilized denatured state.
• BSA adsorption transitioned from reversible to irreversible, confirmed by SPR.
• Stronger surface hydrophilicity effectively suppressed protein adsorption.
• QCM-D D-f plots characterized varying protein binding strengths.

Conclusions:

• Polymer brushes can be effectively synthesized and characterized using QCM-D and SPR.
• Protein adsorption on polymer brushes involves conformational changes from native to denatured states.
• Surface hydrophilicity is a critical factor in controlling protein adsorption and preventing denaturation.
• QCM-D analysis provides insights into protein-surface interactions and binding strength.