Theoretical investigation of the adsorption and sensing behavior of cephapirin on transition metal doped gallium nitride single-walled nanotubes

The extensive use of cephapirin (CPP) in the treatment of mastitis in dairy cattle has raised environmental concerns because residues excreted in an unchanged form can enter soil and water systems, where they promote the survival and spread of antibiotic-resistant bacteria. These resistant microorganisms may transfer resistance genes to other bacterial populations, creating environmental reservoirs of resistance that can ultimately compromise the effectiveness of antibiotics used in both veterinary and human medicine. These risks highlight the need for efficient materials capable of both detecting and removing cephapirin residues from the environment. This study investigates the adsorption and sensing behavior of CPP on transition metal (Cu, Ag, and Au)-doped gallium nitride nanotubes (GaNNTs) using Density Functional Theory (DFT) at the B3LYP-GD3(BJ)/def2-SVP level. The adsorption energies of CPP-Cu@GaNNT, CPP-Au@GaNNT, and CPP-Ag@GaNNT were − 2.313, -2.259, and − 2.177 eV, respectively, confirming chemisorption. Electronic structure, charge transfer, and topological analyses revealed that CPP acts as an electron donor and that adsorption is primarily governed by van der Waals and weak noncovalent interactions. Thermodynamic calculations confirmed that the adsorption process is spontaneous and exothermic for all systems. Sensor analysis showed that Au-doped GaNNT exhibits the strongest sensing response toward CPP. Molecular dynamics simulations performed on multiple initial adsorption configurations further confirmed the thermal stability of the adsorption systems. The collective results indicate that strong adsorption and effective sensing are governed by different electronic factors and are not simultaneously achieved by the same dopant, a finding that provides theoretical insight into the design of transition-metal-doped GaNNTs for the detection and removal of cephapirin residues from environmental systems.