Preparation of Hydrogen Peroxide Sensitive Nanofilms by a Layer-by-Layer Technique

Area of Science:

• Materials Science
• Nanotechnology
• Biochemistry

Background:

• Layer-by-layer assembly is a versatile technique for fabricating functional nanofilms.
• Poly(ethyleneimine) (PEI) and DNA are biocompatible polyelectrolytes suitable for film construction.
• Hemin is a porphyrin derivative known to catalyze reactions involving reactive oxygen species.

Purpose of the Study:

• To develop novel hydrogen peroxide (H₂O₂)-sensitive nanofilms.
• To investigate the H₂O₂-induced decomposition mechanism of these nanofilms.
• To explore the role of hemin in enhancing H₂O₂ sensitivity.

Main Methods:

• Fabrication of nanofilms using layer-by-layer deposition of DNA and hemin-appended poly(ethyleneimine) (H-PEI) via electrostatic interactions.
• Preparation of control films including those with non-covalently adsorbed hemin, without hemin, and using polystyrene sulfonate (PSS) instead of DNA.
• Exposure of fabricated films to varying concentrations of H₂O₂ to assess decomposition.

Main Results:

• The (H-PEI/DNA)₅ nanofilms decomposed upon exposure to 10 mM H₂O₂.
• Hemoglobin-containing (PEI/DNA)₅ films also showed H₂O₂-induced decomposition.
• Control films without hemin or using PSS did not decompose even at 100 mM H₂O₂, confirming the critical role of hemin.
• Decomposition rate was influenced by H₂O₂ concentration, hemin modification ratio, pH, and ionic strength.

Conclusions:

• Hemin-appended DNA/PEI nanofilms exhibit sensitivity to hydrogen peroxide.
• The decomposition mechanism involves H₂O₂-driven generation of reactive oxygen species (ROS) that cleave DNA.
• These findings suggest potential applications for H₂O₂-sensitive nanofilms in sensing and diagnostics.