Recently, implant-related infection remains a pressing issue due to bacterial biofilm formation and antimicrobial resistance. Without using antimicrobial agents, protruding titanium (Ti) nanostructures created by alkaline etching show effective antimicrobial properties via several mechanisms e.g., contact killing and reactive oxygen species (ROS) generation.[1, 2] This work introduces nitrogen rapid thermal annealing (N2-RTA) as a defect engineering approach to improve surface conductivity of Ti surfaces for electrochemical studies.[3] Additionally, antimicrobial dynamics and real-time bacterial interaction on N2-RTA treated protruding Ti nanostructures were investigated via electrochemical studies, including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).

After the N2-RTA treatment, the Ti surfaces became significantly more conductive without affecting the nanostructure morphology. The antibacterial activity of pTi network (NN) and Ti64 nanoflakes (NFs) was confirmed as they maintained peak currents and separations after incubation for 24 hours. Moreover, initial EIS results demonstrated that both pTi NN and Ti64 NFs reduced bacterial attachment on the material surfaces by at least two orders of magnitude.

Aligning with the antimicrobial results, the CV and EIS results supported that pTi NN and Ti64 NFs exhibited significant antimicrobial properties compared to the control surfaces. Additionally, the results clearly showed that N2-RTA was an effective method for improving the conductivity of Ti substrates that could potentially be used for the modulation of bacteria and cells via electrical stimulation to generate cell-instructive surfaces.