Creation of Efficient Biocatalytic Nanoscavengers for Detoxification of Organophosphorus Compounds: Influence of Nanoparticle Type

Biocompatible nanosystems of various types, such as polymersomes based on amphiphilic di- and triblock poly(ethylene glycol)–poly(propylene sulfide) (PEG–PPS) copolymers, liposomes, and solid lipid nanoparticles containing an enzyme, phosphotriesterase (PTE) mutant obtained from Saccharolobus solfataricus hyperthermophilic archaea, can be used as biocatalytic nanoscavengers for detoxification of an organophosphorus compound, paraoxon. The characteristics of the PTE-containing nanosystems determined by dynamic light scattering, namely, a diameter of about 100 nm, a polydispersity of no higher than 0.3, and a negative surface potential, indicate that they can be used for detoxification therapy. Determination of the concentration of polymer nanoparticles in a solution by ultramicroscopy has made it possible to calculate the concentration of the enzyme inside of the nanoparticles, which has appeared to be much higher than the concentration of the toxicant (paraoxon). Membrane permeability for the paraoxon hydrolysis product, para-nitrophenol, and PTE enzyme has been estimated by dialysis. The kinetic study of paraoxon hydrolysis catalyzed by the free PTE and PTE-containing nanosystems has shown that the enzyme encapsulation and the type of nanoparticles do not change the Michaelis–Menten reaction mechanism. The catalytic activity of PTE in the nanosystems has been found to be higher than that of its nonencapsulated form and to depend on the type of nanoparticles. Of the series of the studied nanosystems, polymersomes based on PEG–PPS are most promising for further testing and detoxification therapy.