Electric-field-enhanced high performance of monolayer polyaniline g-C₃N for lung cancer identification: a DFT study

Early cancer diagnosis relies heavily on finding appropriate materials to recognize relevant biomarkers. In this study, we conduct a first-principle density functional theory simulation to investigate the capability of two-dimensional polyaniline (g-C₃N) for detecting propane and acetaldehyde, as known lung cancer biomarkers. The energetically most favorable configurations of the adsorbed systems were determined, and the computed adsorption energy reveals the non-covalent interaction between biomarkers and g-C₃N monolayer. As a result, the adsorption process is reversible, which is fundamental for the long lifespan of biosensors in real applications. On the other hand, acetaldehyde physisorption on the g-C₃N monolayer induces a significant variation in the band gap, suggesting the possible use of g-C₃N as a resistance-based biosensor. Charge transfer analysis shows that both biomarkers act as electron acceptors from the host material. The capability of the g-C₃N monolayer to respond to these biomarkers was also investigated upon applying an external electric field. An electric field considerably enhances the interaction between gas molecules and the g-C₃N monolayer by increasing the adsorption energies and charge transfer values, which are more pronounced for acetaldehyde. The results also show that the g-C₃N monolayer energy band gap in the presence of biomarkers closes at high electric fields. These findings highlight the ability to adjust the sensing properties of the g-C₃N monolayer through an external electric field without requiring any structural modifications.