Electrospun hybrid TiO2/humic substance PHBV films for active food packaging applications

Biowaste valorization: multifunctional hybrid lignin/TiO2 nanostructures for bacterial-biocide disinfection and dye removal

“…Furthermore, it suggests that DL adsorption on the nanoparticle surface can be due to the complexation of Ti 4+ ions with lignin phenolic groups, as previously described for other hybrid titania/polyphenol-based nanocomposites. 51,58 As further proof of this, the physical mixing of lignin and TiO 2 nanoparticles only results in a slight visible region absorption increase, which can be attributed exclusively to lignin intrinsic absorption features within that range, as shown in Fig. S8 †.…”

“…The spectrum of TiO 2 showed a sigmoidal behaviour and the transmittance increasing from 10% to 100% in the range of 300–400 nm, suggesting a maximum TiO 2 absorption band at around 250 nm, as reported elsewhere. 51 On the other hand, hybrid nanostructures showed transmittance values which decrease by increasing the lignin content within nanoparticles (∼50% for TiO 2 _DL25, 40% for TiO 2 _DL50 and ∼20% for TiO 2 _DL100 and TiO 2 _DL200 nanoparticles in the UV-A region with respect to bare TiO 2 nanostructures). This is a key behaviour related to hybrid nanoparticles, which is not present in the spectra of neat TiO 2 nanoparticles (Fig.…”

“…S4 †) reveals rod-like TiO 2 nanoparticles with an average size of approximately 30-35 nm, in accordance with our previous studies. 51 On the other hand, TEM pictures of TiO 2 _DL nanohybrids (Fig. 2) show that hybrid nanoparticles tend to have a spherical shape with an average size of 10 nm, which does not seem to be influenced by the nominal lignin content used in the synthesis.…”

“…68 Although the precise mechanism of action is unknown, it has been proposed that the presence of carboxylic and phenolic groups in the biopolymer leads to an increase in the number of hydrogen bonds with bacterial cell membranes. 56,60,69 This increased affinity is thought to cause irreversible changes in the lipid structure of the membranes, 51 resulting in a decrease in cell wall integrity and increased permeability to reactive oxygen species (ROS), which polyphenol moieties are bound to produce due to their redox active behavior. 51 As a result, not only is pathogenic strain growth slowed, but the activity can also cause bacterial cell death.…”

“…56,60,69 This increased affinity is thought to cause irreversible changes in the lipid structure of the membranes, 51 resulting in a decrease in cell wall integrity and increased permeability to reactive oxygen species (ROS), which polyphenol moieties are bound to produce due to their redox active behavior. 51 As a result, not only is pathogenic strain growth slowed, but the activity can also cause bacterial cell death. Moreover, chemical groups in the lignin side chain, such as a double bond between the α and β carbons or a methyl group bound to the γ carbon, could be responsible for the observed noxious effect of lignin against the selected microorganisms.…”