Integrated analysis of nano Schiff base complex for bioelectronic applications.

Schiff base complexes possess biological activity and electronic features, making them suitable for integration into both core and auxiliary components of bioelectronic technologies. However, integrated studies addressing their electrical, biological, and mechanical properties remain limited. This work investigates a Cu(II) complex based on a Schiff base ligand derived from 2-hydroxy-1-naphthaldehyde and 1,8-diaminonaphthalene. Comprehensive textural analyses using XRD, HRTEM, FESEM, AFM, and N₂ adsorption revealed high surface area, nanoscale morphology, and porosity, which are advantageous for antimicrobial and therapeutic bioelectronic platforms. Mechanical characterization via ultrasonic pulse-echo indicated auxetic behavior, a rare and valuable trait for flexible substrates. The complex also exhibited high ionic conductivity, facilitating charge transport in aqueous environments and contributing to antimicrobial efficacy through ionic disruption of microbial membranes. Thermal analyses showed a phase transition at 44 °C and decomposition onset at 70 °C. A temperature-induced insulator-to-metal transition was observed, suggesting potential for thermally activated sensing, temperature-triggered drug release, and adaptive signal modulation. Biological assays confirmed strong antimicrobial activity, with a 30 mm inhibition zone against Bacillus subtilis (agar well diffusion), and potent cytotoxicity against MCF-7 breast cancer cells, with an IC₅₀ of 18.4 μg/mL (MTT assay). These biological properties enhance the complex's biocompatibility and support its role in long-term bioelectronic device stability, particularly in applications where infection control is essential.