Reflectometric interference spectroscopy-based sensing for evaluating biodegradability of polymeric thin films.

Area of Science:

• Materials Science
• Biotechnology
• Analytical Chemistry

Background:

• Poly(ε-caprolactone) (PCL) is a biodegradable synthetic polymer.
• Evaluating the enzymatic degradation of PCL is crucial for understanding its environmental fate.
• Existing methods for monitoring polymer degradation can be complex or lack sensitivity.

Purpose of the Study:

• To develop and validate a novel reflectometric interference spectroscopy (RIfS)-based sensing system for monitoring the enzymatic degradation of PCL thin films.
• To assess the kinetic parameters of lipase-catalyzed PCL degradation using the RIfS system.
• To demonstrate the utility of RIfS as a label-free, reliable method for evaluating biodegradability.

Main Methods:

• Spin-coating of PCL thin films onto silicon substrates with a silicon nitride interference layer.
• Monitoring degradation via RIfS by tracking shifts in reflectance spectra (Δλ) proportional to film thickness.
• Validation using attenuated total reflection infrared spectroscopy (ATR-IR) for surface analysis and chemical changes.
• Kinetic analysis of sensorgrams using curve fitting software.

Main Results:

• The RIfS system successfully monitored PCL thin film degradation by detecting changes in Δλ.
• Degradation rates correlated with increasing lipase concentration from *Pseudomonas cepacia*.
• ATR-IR analysis confirmed a decrease in surface carbonyl groups, consistent with enzymatic hydrolysis.
• RIfS measurements of film thickness reduction were corroborated by ATR-IR data.

Conclusions:

• The RIfS-based sensing system provides a simple, label-free, and reliable method for evaluating the biodegradability of synthetic materials like PCL.
• This approach enables straightforward kinetic analysis of enzymatic degradation processes.
• The combined RIfS and ATR-IR methodology offers a powerful tool for environmental protection research and material science.