Soft X-ray induced modifications of PVA-based microbubbles in aqueous environment: a microspectroscopy study

Area of Science:

• Materials Science
• Chemical Physics
• Biophysics

Background:

• Poly(vinyl alcohol) (PVA) microbubbles are utilized in various biomedical applications.
• Understanding their stability under radiation is crucial for safe application.

Purpose of the Study:

• To investigate the physicochemical changes in PVA microbubbles upon soft X-ray irradiation.
• To characterize structural and chemical modifications using advanced spectroscopy.

Main Methods:

• In situ characterization using scanning-transmission X-ray microspectroscopy (STXM).
• Soft X-ray irradiation at 520 eV in aqueous suspension.
• Quantitative fitting of radial transmittance profiles.
• Near-edge X-ray absorption fine structure (NEXAFS) spectroscopy at the C K-edge.

Main Results:

• Continuous shrinkage of microbubble volume observed with increasing radiation dose.
• No significant change in membrane thickness, but volume contraction occurred.
• PVA network degradation identified, with formation of carbonyl/carboxyl species.
• Increased content of unsaturated bonds in the microbubble membranes.

Conclusions:

• Soft X-ray irradiation induces significant structural and chemical changes in PVA microbubbles.
• The observed degradation is linked to the formation of specific chemical species and bond alterations.
• STXM and NEXAFS are effective tools for in situ analysis of radiation-induced effects on microbubbles.