Geometry-dependent DNA-TiO₂ immobilization mechanism: A spectroscopic approach

Area of Science:

• * Materials Science
• * Nanotechnology
• * Biochemistry

Background:

• * DNA nucleotides serve as molecular recognition systems for disease detection biosensors.
• * Immobilization mechanisms and charge transfer in DNA-electrode systems require further clarification.
• * Nanostructured titanium dioxide (TiO2) is a promising material for electrode modification.

Purpose of the Study:

• * To characterize molecular groups involved in direct DNA immobilization on nanostructured TiO2.
• * To evaluate the influence of DNA geometry on immobilization efficiency and charge transfer.
• * To understand the DNA-TiO2 interface for enhanced biosensor applications.

Main Methods:

• * Electrochemical and spectroscopic techniques were employed.
• * X-ray photoelectron spectroscopy (XPS) analyzed O1s, P2p, and C1s core levels.
• * X-ray absorption spectroscopy (XAS) examined the Ti2p edge.

Main Results:

• * DNA immobilization on TiO2 occurs through covalent (POTi) bonds, confirmed by XPS and XAS.
• * A novel species at 138.5 eV in P2p XPS spectra is crucial for DNA-TiO2 immobilization.
• * Immobilization efficiency is geometry-dependent, favoring plasmid ds-DNA over PCR ds-DNA.
• * Charge transfer pathways at the DNA-TiO2 interface vary based on molecular groups involved in C1s→LUMO transitions.

Conclusions:

• * The study elucidates DNA immobilization mechanisms on nanostructured TiO2, highlighting covalent bonding.
• * DNA geometry significantly impacts immobilization efficiency and charge transfer dynamics.
• * Findings provide foundational insights for designing advanced DNA-based biosensors and aptamers.