Fundamental Study on Novel Biological Indicator Using DNA-Labeled Microbeads for Evaluating Nonthermal Plasma Sterilization

Nonthermal atmospheric-pressure discharge plasma is considered important for sterilization. Reactive species, such as active oxygen species, radicals, and nitrate ions, generated by the discharge plasma damage the target bacterial cell wall/membrane and DNA. Several plasma sterilization methods have been proposed, including dielectric barrier discharge (DBD). To achieve effective sterilization, it is necessary to evaluate their characteristics using many parameters. This letter aims to demonstrate a proof-of-concept of a novel biological indicator for plasma sterilization. A biological indicator is used to verify sterilization outcomes. We employ DNA-labeled microbeads as biological indicators for the rapid visualization of plasma sterilization. This is based on our recently developed method for visual detection of DNA molecules. If plasma-derived factors cause the degradation of the DNA attached to the microbeads, this can be confirmed by visualization. Herein, we present the correlation between sterilization and visualization in the case of DBD. This method offers a rapid evaluation of plasma sterilization because it easily and quickly determines the sterilization capability of the plasma.