In recent years, plastics have formed a significant part of waste and environmental pollution. For this reason, in order to reduce the use of petroleum products and to minimize environmental issues, biodegradable polymers have been widely investigated as an alternative to plastic. However, these polymers have limitations such as weak mechanical and barrier properties, which is suggested the use of nanoparticles as a solution to improve the properties and strengthen of these polymers. Therefore, the aim of this research is to prepare the Opopanax film containing graphene quantum dot nanoparticles doped with nitrogen, which has ultraviolet radiation blocking, antioxidant and anti-microbial properties and increases the shelf life of food. The solution containing graphene quantum dots doped with nitrogen (N-GQD) was made using fructose precursor as a carbon source and nitric acid as a nitrogen source to supply the dopant element in order to increase the performance of graphene quantum dots with the help of hydrothermal method. Fourier transform infrared spectroscopy (FTIR) was performed to investigate the functional groups, confirming the synthesis of graphene quantum dots and effective nitrogen doping in their structure. High resolution transmission electron microscope (HR-TEM) images showed that graphene nanoparticles are spherical and their average diameter is 6.5±7.2 nm and in-plane lattice spacing is 0.252 nm. Absorption spectroscopy and free radical scavenging assay (DPPH) showed that the resulting solution has high UV absorption and antioxidant properties. The surface charge of particles was measured by zeta potential analysis as 8.6 ± 0.5 mV. In the next step, Opopanax film was prepared using Opopanax resin which was extracted by kejeldal distillation method using ethanol, along with ethyl cellulose as a hardener and containing N-GQD solution using casting method. FTIR results confirmed the presence of nitrogen-doped graphene quantum dot in the structure of Opopanax film. The morphology of the films was examined by Field Emission Scanning Electron Microscopy (FESEM) and showed a homogeneous and uniform dispersion of N-GQD in the polymer matrix. The anti-ultraviolet properties of Opopanax films were investigated with a spectrophotometer. The antioxidant properties of N-GQD was also eva‎luated by DPPH free radical scavenging method. The results showed that the presence of N-GQD in the structure of Opopanax films has increased the anti-ultraviolet radiation and antioxidant properties of the films. The results of the thickness, water solubility and humidity tests showed that the values of these three parameters of Opopanax film increased due to the addition of N-GQD, while the permeability to water vapor and swelling ratio of the treated film decreased. Adding N-GQD to the film did not significantly change its mechanical properties (tensile strength and elongation at break) and the resulting film had good flexibility. By coating tangerine fruit with Opopanax film solution and Opopanax film containing N-GQD, the effect of films on food shelf life was eva‎luated and it was found that after 15 days of storage at 25℃, the coated fruits compared to the control did not show any mold growth, which is a confirmation of the presence of anti-fungal, anti-microbial and antioxidant properties of Opopanax and N-GQD film. But the Opopanax film had a lower marketability. Finally, it can be said that Opopanax film containing N-GQD has a suitable capability for food packaging due to its ultraviolet absorption and high antioxidant capacity, acceptable physical and mechanical properties and inhibition of microbial growth

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مهدي كديور

مهرنوش جعفري , اميرحسين گلي