Zinc Oxide and Polyamine Nanoparticles: Interaction Mechanism study

MEDINA AV; LEDESMA, ANA E.; MELLANO, MARIA FERNANDA; PEREZ, HUGO

Encuentro; LI Reunion Anual de la sociedad Argentina de Biofisica; 2023

Abiotic stress in plants is considered a major problem in agriculture. Stress types includedrought, salinity, alkalinity, and temperature, among others, which minimise the growthand productivity of crops. During their life cycle, plants are exposed to several types ofabiotic stresses and develop defence mechanisms to cope with them using differentphysiological pathways. In recent years, the use of exogenous compounds such aspolyamines (PAs) and nanoparticles (NPs) has grown to counteract different types ofabiotic stress and promote crop growth. However, no experimental works on theinteraction of these compounds has been reported to date. Therefore, this work proposesto study the interaction of plant polyamines, such as putrescine (PUT), with zinc oxidenanoparticles (ZnO-NPs), both of which are used in foliar form in plants. To conduct thisstudy, the fluorescence of ZnO-NPs (λexc = 370 nm) as a function of the PUTconcentration was used. The decrease in the fluorescence spectra of ZnO-NPs due to theincrease in PUT was adjusted using the Stern– Volmer equation, obtaining a value of ≈2000 M-1 at 25°C. The increase in temperature decreases the value of the KSV constant,suggesting that the quenching mechanism is stationary. Furthermore, it was determinedthat the thermodynamic parameters ΔS and ΔH are positive, indicating that the formationof the ZnO-NPs-PUT complex is mediated by hydrophobic interactions. On the other hand,a slight bathochromic shift of the maximum emission peak of ZnO-NPs was observedbecause of the presence of PUT, which is associated with an increase in the size of thenanoparticle. The last result is in agreement with the analysis obtained by dynamic lightscattering (DLS), where PUT increases the size of the ZnO-NPs. These results demonstratethe adsorption of polyamine on nanoparticles, which will serve as a basis for futureexperimental strategies.