Studies of Ponceau 4R food colorant and zinc oxide nanoparticles containing it interactions with DNA and evaluation of their antimicrobial activity

The current study describes design and synthesis of silica-coated zinc oxide nanoparticles containing Ponceau 4R food colorant (named as ZnO@SiO2@APTMS/P4R). The interactions of Ponceau 4R and ZnO@SiO2@APTMS/P4R with calf thymus-DNA were investigated It should be noted that the competitive binding experiment revealed that both Ponceau 4R and ZnO@SiO2@APTMS/P4R could release Hoechst 33258. As inferred from the results the binding of the Ponceau 4R and ZnO@SiO2@APTMS/P4R with DNA were surface binding, mainly due to groove binding. Furthermore, antibacterial properties of ZnO, Ponceau 4R and ZnO@SiO2@APTMS/P4R samples against gram-positive bacteria and gram-negative bacteria were examined and the resulting data were compared with the known antibiotic tetracycline. Interestingly, in most cases Ponceau 4R performs antimicrobial activities better than tetracycline that it is important for food preservation containing this colorant. In addition, the ZnO@SiO2@APTMS/P4R exhibited good antimicrobial effectiveness not only to Gram-positive but also to Gram-negative bacteria. Novelty impact statement The silica-coated zinc oxide nanoparticles containing Ponceau 4R have been synthesized and fully characterized by FT-IR, TEM, TGA, XRD, SEM/EDX and Zeta potential analysis. The results showed that the Ponceau 4R food colorant and the nanoparticles interact with calf thymus-DNA as groove binders. Interestingly, Ponceau 4R performs excellent antibacterial activities against both gram-positive and gram-negative in comparison to tetracycline and it is important for food preservation containing this colorant.