Impact of silver nanoparticles stabilized by diffrent coatings on activity and expression of antioxidant enzymes in tobacco seedlings (Nicotiana tabacum L.)

Nanočestice srebra (AgNP) ubrajamo u često korištene nanomaterijale zbog njihovih anitmikrobnih svojstava koja im osiguravaju veliki tržišni potencijal i široku primjenu. Brojna toksikološka ispitivanja ukazuju na važnost istraživanja i razumijevanje potencijalno štetnog učinka AgNP na okoliš. Ovaj rad usmjeren je na ispitivanje toksičnosti 100 μM AgNP stabiliziranih omotačima od polivinilpirolidona (AgNP-PVP) i cetiltrimetilamonijevog bromida (AgNP-CTAB) i 100 μM srebrova nitrata (AgNO3), samih i u kombinaciji s 500 μM cisteinom, na klijance duhana (Nicotiana tabacum L.). Spektrofotometrijska analiza stabilnosti AgNP u hranjivoj podlozi ½ MS pokazala je veću stabilnost AgNP-PVP u odnosu na AgNP-CTAB, dok je dodatak cisteina narušio stabilnost AgNP-PVP, a kratkoročno produljio stabilnost AgNP-CTAB. Spektrofotometrijsko mjerenje aktivnosti antioksidacijskih enzima (superoksid dismutaza, katalaza, askorbat i pirogalol peroksidaza), detekcija njihovih izoformi elektroforezom u nativnim uvjetima i imunokemijska metoda pokazale su promjene u njihovoj aktivnosti i ekspresiji. Najosjetljivijim enzimom pokazala se askorbat peroksidaza. Usporedbom tretmana s AgNP i AgNO3 utvrđena je veća toksičnost AgNP-CTAB te manja toksičnost AgNP-PVP prema većini parametara, u odnosu na AgNO3. Dodatak cisteina nije utjecao na fitotoksičnost AgNP-PVP, ali je djelomično ublažio toksičan učinak AgNP-CTAB, što navodi na zaključak da fitotoksičnost AgNP-PVP proizlazi većim dijelom iz samih nanočestica, dok fitotoksičnost AgNP-CTAB proizlazi iz otpuštenih Ag+ ili omotača CTAB.Silver nanoparticles (AgNP) are one of the most frequently used nanomaterials, due to their antimicrobial properties, which provide them great market potential and wide application. Numerous toxicological studies indicate the importance of investigating and understanding potentially harmful effects of AgNP on the environment. This work is focused on toxicity testing of 100 μM AgNP stabilized with polyvinylpyrrolidone (AgNP-PVP) and cetyltrimethylammonium bromide (AgNP- CTAB) coatings and 100 μM AgNO3, single and in combination with 500 μM cysteine, applied to tobacco seedlings (Nicotiana tabacum L.). Spectrophotometric analysis of AgNP stability in ½ MS nutrient medium showed higher stability of AgNP-PVP compared to AgNP-CTAB, while cysteine addition disturbed AgNP-PVP stability and prolonged the stability of AgNP-CTAB in the short term. Spectrophotometric measurement of activity of antioxidant enzymes (superoxide dismutase, catalase, ascorbate and pyrogallol peroxidase), detection of their isoforms by native electrophoresis and immunochemical method showed changes in their activity and expression. Ascorbate peroxidase proved to be the most sensitive enzyme. Comparison of AgNP and AgNO3 treatments revealed higher toxicity of AgNP-CTAB and lower toxicity of AgNP-PVP compared to AgNO3, according to the majority of the parameters. Addition of cysteine did not affect AgNP-PVP phytotoxicity, but partially alleviated toxic effects of AgNP-CTAB, leading to the conclusion that phytotoxicity of AgNP-PVP comes predominantly from the nanoparticles, while AgNP-CTAB phytotoxicity results from the released Ag+ ions or CTAB coating