Modulated Optoelectronic Properties of MOF/CNF Bionanocomposite Films for Bacterial Growth Control under Visible Light

The present work reports an experimental and theoretical investigation of tuning the optoelectronic properties of MIL-125-NH₂ nanoparticles by grafting aromatic molecules. The postsynthetic modification of the MOF MIL-125-NH₂ with 3,4-dihydroxybenzaldehyde (DBA) resulted in a 23% reduction in the bandgap energy, from 2.71 to 2.08 eV, while increasing the absorbance throughout the visible region of the spectrum, which could be attributed to stabilization due to enol-imine/keto-enamine tautomerism, as supported by DFT theoretical calculations. Pristine and grafted MOFs were assembled into cellulose nanofibers (CNF) for the preparation of functional CNF-based bionanocomposites. The mechanical properties of the films improved, with Young’s modulus increasing from 1.3 GPa in CNF to 7.5 GPa in the film with 20% MOF loading. The potential of the developed materials for photocatalytic antimicrobial therapy was evaluated against Staphylococcus aureus (S. aureus). In vitro tests showed that both bionanocomposite films with pristine and DBA-modified MOF remarkably reduced bacterial growth due to the photocatalytic action of the MOF under visible light. The inhibition values were around 58% and 72%, respectively, while minimal inhibition was observed under dark conditions. These initial results support the potential use of the developed bionanocomposite films as wound dressings.