Photocatalytically Active Zinc Oxide and Titanium Dioxide Nanoparticles in Clonal Micropropagation of Plants: Prospects

Abstract

The search for effective and nontoxic sterilization drugs for plants against common phytopathogenic microorganisms is a major challenge to improve the biotechnology of plant clonal micropropagation. An analysis of 92 studies that describe the potential use of ZnO and TiO₂ nanoparticles as antimicrobial agents in biotechnology showed that their biological effects depend on several factors: photocatalytic activity, particle size, concentration, morphology, and surface modification. The mechanisms of toxicity, among which the primary one is generation of reactive oxygen species leading to oxidative stress, are also due to these factors. The data describing the direct influence of ZnO and TiO₂ nanoparticles on plants, however, are contradictory, which is probably because of the various particle shapes and sizes, their concentrations, and the species characteristics of the plants studied. These studies have confirmed that photocatalytically active ZnO and TiO₂ nanoparticles may be used as bactericidal and fungicidal drugs for sterilization of explants during clonal micropropagation of plants, while taking into account the possible phytotoxicity of these particles.