Oxygen vacancy-engineered interfacial bonding for DNA conjugation on nanopatterned rutile TiO2: experimental and in silico study

Abstract

Bioconjugation of nucleotides with oxide surfaces forms the fundamental basis for numerous biotechnological applications. Here, we investigate the role of nanopatterned rutile TiO2 surfaces, with particular emphasis on oxygen vacancy states among the irradiation-induced surface modifications, generated during ion-beam-induced nanopatterning, in DNA adsorption. The formation of possible Ti-O-N related interfacial configuration together with the associated charge-transfer characteristics suggests that irradiation-induced surface modifications, including oxygen-vacancy states and other defects, contribute to the observed interfacial electronic behaviour. In the absence of nanopatterning, such irradiation-induced defect states are not observed, and DNA adsorption appears to occur predominantly through Ti-N-related interactions. Experimental findings are corroborated by density functional theory (DFT) calculations focused on adenine adsorption on TiO2. The results reveal electron transfer from the surface to the adenine molecule, directly influencing local interfacial electronic interactions. DFT results indicate that while pristine TiO2 sites govern adsorption stability, oxygen-vacancy states are associated with enhanced interfacial charge transfer, thereby modulating the electronic characteristics of the adenine-TiO2 interface. The implications of these electronic effects for DNA immobilization efficiency and functional performance remain beyond the scope of the present study.