Biogenic synthesis of selenium nanoparticles using olive pomace extract

Prilikom procesa proizvodnje maslinovog ulja kao nusprodukt nastaju velike količine čvrstog ostatka koji se naziva komina masline. Ona je bogata polifenolima, spojevima koji imaju dokazano antioksidacijsko djelovanje. Cilj ovog rada bio je razviti proces biogene sinteze nanočestica selena korištenjem ekstrakta komine masline kao prirodnog sredstva za oblaganje koje će potencijalno sa selenom ostvarivati i sinergističko antioksidativno djelovanje. Selen kao sastavni dio enzima glutation peroksidaze djeluje posredno antioksidativno, dok polifenoli imaju izravan učinak na gašenje slobodnih radikala, jaki su reducensi te keliraju metale. Provedena je optimirana sinteza nanočestica selena s obzirom na koncentraciju EM te je DLS analizom ispitana raspodjela veličine čestica, stabilnost i zeta potencijal. Antioksidacijski potencijal ispitan je ABTS i Folin-Ciocalteu metodama. Kao pozitivna kontrola sintetskog procesa korištena je kemijska sinteza SeNČ korištenjem polivinilpirolidona. Biogenom sintezom uspješno su sintetizirane dvije značajne frakcije SeNČ prosječne veličine 35 i 215 nm koje u testovima stabilnosti skladištenjem pokazuju određen stupanj nestabilnosti. Analizom rezultata zeta potencijala utvrđeno je da je elektrostatsko odbijanje između sintetiziranih SeNČ vrlo dobro (cca -22,5 mV). Za razliku od kemijski sintetiziranih SeNČ, biogeno sintetizirane SeNČ pokazuju značajnu antioksidativnu aktivnost u smislu izravnog gašenja slobodnih radikala te ukupnog redukcijskog potencijala. Najbolje rezultate pokazao je uzorak koncentracije EM 0,862 g/L. Povećanje koncentracije EM iznad 0,862 g/L nema utjecaj na dodatan porast antioksidacijskog potencijala SeNČ. Rezultati ovog rada značajno doprinose razvoju saznanja o mogućnostima korištenja ekstrakta komine masline u razvoju nanonutraceutika točnije, mogućnostima primjene spomenutih ekstrakata kao prirodnih funkcionalnih sredstava za oblaganje metalnih nanočestica.During the olive oil production process, large amounts of a solid residue called olive pomace is produced. It is rich in polyphenols, compounds with proven antioxidant activity. The aim of this research was to develope the process of biogenic synthesis of selenium nanoparticles using olive pomace extract (OPE) as a natural coating agent that will potentially have a synergistic antioxidant effect with selenium. Selenium as the component of glutathione peroxidase has an indirect antioxidant effect, while polyphenols have a direct effect on scavenging free radicals, are strong reducing agents and chelate metals. Optimized synthesis of SeNPs has been conducted using different concentrations of OPE. Nanoparticle size distribution, stability and zeta potential was determined by DLS analysis. Antioxidant activity was examined by ABTS and Folin-Ciocalteu methods. Chemical synthesis of SeNPs using polyvinylpyrrolidone was used as a positive control of the synthetic process.. Two significant fractions of SeNPs with an average size of 35 and 215 nm were successfully synthesized by biogenic synthesis, which showed a certain degree of instability in storage stability tests. Analysis of zeta potential showed that the electrostatic repulsion between the synthesized SeNPs was satisfying (approx. -22,5 mV). Unlike chemically synthesized SeNPs, biogenically synthesized SeNPs show significant antioxidant activity in terms of direct scavenging of free radicals and overall reduction potential. The best results were obtained for the sample prepared with 0.862 g/L OPE while further increase of OPE concentration (above 0.862 g/L) had no effect on antioxidant potential of SeNPs. The results of this research significantly contribute to current knowledge on possibilities of using olive pomace extract in the development of nanonutraceuticals, more precisely, the possibilities of using these extracts as natural functional coating agents in formulation of metal nanoparticles