Magnetically responsive chitosan-pectin films incorporating Fe3O4 nanoparticles with enhanced antimicrobial activity

Chitosan-pectin films with iron oxide (Fe3O4) magnetic nanoparticles were prepared by solution casting in order to produce biopolymer based magnetically active materials. Infrared (FTIR) spectra indicated physical interactions between the matrix and nanoparticles, corroborated by differential scanning calorimetry (DSC) results. In addition, thermal characterization suggested that the interactions between chitosan, pectin and the nanoparticles resulted in a less compact structure, influencing the film mechanical properties. Regarding vibrating-sample magnetometry (VSM) and electrical analysis, chitosan-pectin films with Fe3O4 nanoparticles showed ferrimagnetic behavior, with an increase of the dielectric constant as the nanoparticle concentration increased. Furthermore, films displayed enhanced antimicrobial activity against Escherichia coli (Gram-negative) and Staphylococcus epidermidis (Gram-positive) bacteria. Therefore, chitosan-pectin films with Fe3O4 magnetic nanoparticles provide promising results for active and intelligent food packaging applications.This research was funded by MCI/AEI/FEDER, UE, grant number RTI2018-097100-B C22. This work was also supported by the Portuguese Foundation for Science and Technology (FCT) under strategic funding UIDB/04650/2020, UID/FIS/04650/2021, project PTDC/FIS-MAC/28157/2017, and Investigator FCT Contracts 2020.02915.CEECIND (D.M.C) and 2020.04028.CEECIND (C.M.C.) funded by national funds through FCT and by the ERDF through the COMPETE2020-Programa Operacional Competitividade e Internacionalização (POCI). The authors also acknowledge funding from the Basque Government Industry and Education Department under the ELKARTEK program. Thanks are also due to the Advanced Research Facilities (SGIker) from the UPV/EHU