Poled piezo plates kill bacteria resting on their surface
Poled piezo plates kill bacteria resting on their surface lead image
Bacterial cells haul negative electrical charge on their surfaces that aide cell membranes in their selectivity for what passes through into (or out of) a given cell. This biochemical trick also exposes a weakness that allows us to develop antibacterial treatments that target this charge and don’t require harsh chemical treatments. Research reported in the Journal of Applied Physics describes using a ferroelectric material to depolarize bacteria cells on the surface, fatally damaging their biochemistry without expending energy.
The authors of the report synthesized the piezoelectric ceramic material BaCaTiZrO3 (BCTZO), which they then poled at different electric field strengths from 1.32 to 2.90 kilovolt per millimeter. The most successful results came from (smooth) samples positively poled by the largest electric field. 88 percent of the E. coli bacteria in a suspended solution died in less than an hour of simply sitting on the surface of the positively poled piezo plate.
Unpoled or negatively poled surfaces, meanwhile, had similar values for bacterial survival. These surfaces lacked the attractive positive charge that draws in and depolarizes the negatively charged bacteria.
Incorporating sonication sped up the macroscopically passive, yet microscopically active, process, boosting effectiveness and applicability potential. The sonically driven vibrations increased the measured surface potential changes, which ramped up electrolysis and the intracellular production of reactive oxygen species. These potential changes were larger for the samples with higher field treatments, which also correlated with faster and better E. coli eradication rates.
The potential health applications for piezoelectrics in bioinspired devices offer plenty of opportunities for further development. “We would like to improve the bacterial disinfection rate with the better material selection and fabrication process,” said co-author Rahul Vaish. “The next step would be testing these materials against other microorganisms like gram-positive bacteria, pathogenic bacteria, multidrug-resistant bacteria and fungal strains.”
Source: “Surface-selective bactericidal effect of poled ferroelectric materials,” by Sandeep Kumar, Rahul Vaish, and Satvasheel Powar, Journal of Applied Physics (2018). The article can be accessed at https://doi.org/10.1063/1.5024721 .
