Amine-responsive bilayer films with improved illumination stability and electrochemical writing property for visual monitoring of meat spoilage

Amine-responsive bilayer films were developed by using agar (AG), anthocyanins (AN), gellan gum (GG) and TiO2 nanoparticles for visual monitoring of meat spoilage. The AG-AN layer worked as the sensing layer to volatile amines, while GG-TiO2 layer served as the light barrier layer and simultaneously the conducting layer to improve the illumination stability and electrochemical writing ability of the AG-AN layer, respectively. The Scanning electron microscopy (SEM) images and X-ray diffraction (XRD) spectra indicated the successful fabrication of bilayer films. Illumination experiments showed that the incorporation of TiO2 in the GG-TiO2 layer significantly improved the illumination stability of AN in the AG-AN layer. Meanwhile, electrochemical writing process could be easily conducted on the AG-AN layer in the presence of GG-TiO2 layer, indicating the feasibility of ink-free printing on bilayer biopolymer films. The AG-AN/GG-2%TiO2 film presented a limit of detection of 0.018 mM to trimethylamine (TMA), a typical basic gas generated during meat spoilage. Based on its good illumination stability and sensing ability to basic gases, the AG-AN/GG-2%TiO2 film exhibited rose red-to-green color changes along with the spoilage of pork and silver carp, indicating its great potential for monitoring meat spoilage in intelligent food packaging

Nanocomposite Gels via in Situ Photoinitiation and Disassembly of TiO₂–Clay Composites with Polymers Applied as UV Protective Films

We report a facile solution polymerized approach to prepare nanocomposite hydrogels. The electrostatic assembly of positive TiO₂ nanoparticles with negative clay nanosheets obtained TiO₂–clay composite particles, which was disassembled by the solution polymerization of <i>N</i>,<i>N</i>-dimethylacrylamide and homogeneously interacted with poly­(<i>N</i>,<i>N</i>-dimethylacrylamide) chain to form nanocomposite hydrogels. The final nanocomposite hydrogels are mechanical tough and transparent, which has the maximum 598.21 KPa compressive strength. The immobilized TiO₂ not only acted as the photo-initiator for radical polymerization but also endowed the nanocomposite gel films good UV protective performance. This strategy can be very useful for preparing nanocomposite hydrogels with different functions