Spectroscopic study of maghemite nanoparticles surface-grafted with DMSA

Area of Science:

• Nanomaterials Science
• Surface Chemistry
• Spectroscopy

Background:

• Nanosized maghemite particles were functionalized with meso-2,3-dimercaptosuccinic acid (DMSA).
• Investigating the surface content of DMSA and its oxidation to disulfide (S-S) bridges is crucial for understanding nanoparticle behavior.

Purpose of the Study:

• To quantify DMSA molecules on maghemite nanoparticle surfaces.
• To study the oxidation of thiol (S-H) groups to S-S bridges.
• To establish a method for evaluating the [S-H]/[S-S] ratio.

Main Methods:

• Utilized photoacoustic spectroscopy to monitor S-H groups.
• Employed Raman spectroscopy to detect S-S bridges.
• Correlated spectroscopic data with nanoparticle hydrodynamic diameter.

Main Results:

• Established a linear relationship between Raman (S-S) and photoacoustic (S-H) intensities, confirming oxidation with increasing DMSA grafting.
• Developed a method to evaluate the [S-H]/[S-S] ratio.
• Observed reduced hydrodynamic diameter with increased DMSA grafting, supporting intra/inter-particle S-S bridging models.

Conclusions:

• The study successfully quantifies DMSA surface functionalization and oxidation on maghemite nanoparticles.
• The combined spectroscopic approach provides a reliable method for assessing S-H and S-S states.
• Findings offer insights into nanoparticle assembly and stability influenced by surface chemistry.