ИСТИНА

Spread of highly dispersed and reactive microplastics (MP) is of concern due to their potential toxicity. MP particles loaded with biocidal compounds are especially dangerous. The toxicity of MP-biocide complexes can greatly depend on their composition and environmental properties. In the work, the antimicrobial properties of binary complexes of model MP particles, microspheres of butadiene-styrene copolymer with carboxyl groups on the surface, and the toxic cationic polydiallyldimethylammonium chloride (PDADMAC).PDADMAC was quantitatively adsorbed on the surface of microspheres. Complexes resistant to aggregation were synthesized at a molar ratio of the functional groups of the polycation and microspheres Z = [N+]/[COO-] ≤ 0.7 and Z ≥ 1.2; in the first case, negatively charged complexes were formed, in the second, positively charged ones. Aqueous dispersions of microspheres did not exhibit antimicrobial activity against grampositive and gram-negative bacteria; on the contrary, the polycation showed high activity against both types of microorganisms. The antimicrobial activity of the “cationic” complex with Z = 1.2 was comparable to that of the native polycation. “Anionic” complexes with Z ≤ 0.7 had less toxicity, which decreased as the polycation was distributed over more and more MP particles. Addition of microsphere-PDADMAC complexes into the soil did not have a toxic effect on soil microorganisms.