Abstract
The piezoelectric materials, barium titanates (BaTiO 3 ) in various sizes 50, 200, and 500 nm, were modified with polyethyleneimine (PEI) as PEI@BaTiO 3 to improve antibacterial activities. The realization of PEI modification was confirmed with the peaks appeared on the Fourier transform infrared (FTIR) spectrum of BaTiO 3 nanoparticles ∼1650 cm −1 , which are assigned to N–H stretching vibrations. The isoelectric points of BaTiO 3 nanoparticles increased to about pH 10 after PEI modification, which were pH 3–4 range for pristine BaTiO 3 nanoparticles. BaTiO 3 nanoparticles below 200 nm showed antibacterial activity against gram‐negative bacteria with 25 mg/mL minimum inhibition concentration (MIC) value but determined not effectively against gram‐positive pathogens. However, positively charged PEI@BaTiO 3 particles render high antibacterial potency on wide range of bacteria with almost four‐fold lower MIC values than pristine BaTiO 3 nanoparticles. Safe concentration of BaTiO 3 nanoparticles on L929 fibroblast cells was found at 100 µg/mL with more than 90% cell viability. Cytotoxicity was slightly decreased for PEI@BaTiO 3 particles, and 50 µg/mL concentration of PEI@BaTiO 3 particles could be used in vivo applications without any significant toxicity. The piezoelectric effect of pristine BaTiO 3 generated a higher voltage for 50 nm particles compared to the larger particles. Also, PEI@BaTiO 3 generated voltages, somewhat attenuated and rapidly decayed in time, showed high consistency.
