Preparation And Application Of UV-blocking Biodegradable Film And Meat Freshness Smart Label

With the progress of society,white pollution and food deterioration have caused great damage to the environment and economy,which also seriously affect the safety of human survival.The development of green degradable materials and intelligent detection technology is an important topic of modern scientific research.The films which have been given certain functions and intelligence,have a wide range of applications in the agricultural,food and pharmaceutical industries.In this paper,combining nanotechnology and biomass materials,taking the development of biodegradable films and the detection of food freshness as the starting point,a nano-silica-modified PBAT/lignin biodegradable films with UV resistance and excellent mechanical properties was developed.Besides,the fluorescent smart label with CDs and Cd Te semiconductor nanoparticles(Cd Te NPs)ratio probes,have a good role in identifying the freshness of meat products.These works provide new ideas and methods for the preparation of green degradable films and smart labels for food freshness.(1)The PBAT/SL composite films containing sodium lignosulfonate(SL)and silane-modified nano-silica(m-Si O₂)are prepared.The PBAT/SL composite films show good UV-blocking ability.When the addition of SL reaches 10 wt%(P/L10),the UV-B blocking of the composite film can reach about 100%.However,the tensile strength of P/L10 is approximately32%lower than that of neat PBAT.The tensile strength of the composite films with 2 wt%m-Si O₂(P/L10/S2)is 55%higher than that of P/L10 and 5%higher than that of neat PABT.As a nano-filler,m-Si O₂ is well distributed into PBAT/SL composites,leading to improved tensile properties and the compatibility of PBAT with SL.(2)The ratiometric probe for H₂S detection is constructed by mixing CDs with Cd Te NPs.In order to prepare portable fluorescence sensing film,the CDs are modified by organosilane based on the simply hydrothermal reaction of regenerated lignin and?-aminopropyl triethoxysilane.The ethyoxyl groups on the surface of CDs can be hydrolysed to form silanol groups at 80?.As a result,the mixture solution of CDs and Cd Te NPs can be converted into a fluorescent film.Under an UV lamp,the red fluorescence of Cd Te NPs is gradually quenched by H₂S,while the blue fluorescence of CDs is unaffected.Thus,the system present visually color change from pink to blue.The system shows the satisfying sensitivity for the detection of H₂S with a detection limit of 70 n M by fluorescent spectrum method.The fluorescent films have been successfully applied in monitoring the freshness of pork products.