Preparation And Application Of Photoinduced Antibacterial Films Based On Berberine Complex

As an advanced green material,photosensitive antibacterial materials rely on photosensitizers(PSs)to produce reactive oxygen species(ROS)under light to kill bacteria.It has the characteristics of high killing efficiency,broad spectrum,long-term stability,high durability,low toxicity and low environmental pollution.It can be effectively used in food active packaging to protect food from microbial pollution.Berberine(BBR)is a natural photosensitizer derived from herbaceous plants such as Phellodendron amurense and Coptis chinensis.However,because it is not homologous to medicine and food,its high water solubility hinders its application as a photosensitive bacteriostatic agent in food packaging film.In order to solve the above problems,three berberine complexes were prepared by ion exchange between berberine and anionic surfactants:sodium palmitate(PA),Docusate sodium(AOT)and anionic polysaccharide sodium alginate(SA).The FTIR,photostability and photosensitive antibacterial properties of the complexes were explored.Berberine sodium palmitate complex(BP)was selected as antibacterial agent and polyvinyl alcohol(PVA)was used as film substrate;Two kinds of antibacterial packaging materials,PVA-BP film and PVAc-BA coating,were prepared by using berberine and dioctyl succinate sodium sulfonate complex(BA)as antibacterial agent,polyvinyl acetate(PVAc)as plasticizer and PVDC as film matrix.The microstructure,dissolution,fluorescence lifetime and photosensitive antibacterial properties of the membrane were studied.The actual fresh-keeping effect of film in fresh pork storage was evaluated.The main research results and conclusions of this paper are as follows:1.BP complex was prepared by ion exchange,and its water solubility was greatly reduced.The photosensitivity was stable,and the absorption peak did not decrease significantly after treatment with light(60m W/cm~2)for 90 min(P<0.05).The inhibition rate of light(60m W/cm~2)for 5 min to S.aureus was 71.15+3.21%,and that of light(60m W/cm~2)for 30 min to E.coli was 90.7+2.06%.The antibacterial intensity and light intensity increased with time.PVA-BPx(x=0.1,0.3,0.5,x is the content of BP,that is,the weight ratio of BP to PVA W/W%)film was further prepared to effectively alleviate the precipitation of BBR in food simulation solution.The light transmittance is more than65%.PVA-BP_0.1the bacteriostatic rate of film light treatment(60m W/cm~2)for 10 min to S.aureus was 75.36+11.47%,and the bacteriostatic rate of light treatment for 40 min to E.coli was 54.8+1.45%.The antibacterial rate increased with the increase of light intensity,time and BP content.Through SOSG detection and analysis,it is found that light treatment produces ~1O₂to kill bacteria.PVA-BP_0.5compared with the control group,the cold fresh pork packaged with film has good preservation effect after light,which can effectively prolong the shelf life of pork.2.BA complex was prepared by ion exchange,and its water solubility was greatly reduced.The photosensitivity was stable,and the absorption peak did not decrease significantly after treatment with light(60m W/cm~2)for 90 min(P<0.05).The inhibition rate of light(60m W/cm~2)for 5 min to S.aureus was 53.94+2.75%,and that of light(60m W/cm~2)for 30 min to E.coli was 54.02+7.28%.The antibacterial rate increased with the increase of light intensity and time.PVAc-BAx(x=1,3,5,x is the content of BA,that is.the weight ratio of BA to PVAc W/W%)coating was further prepared,and the light transmittance was more than 85%.The antibacterial rate of PVAc-BA₃coating on S.aureus was 67.07+2.99%after 10 min of light treatment(60m W/cm~2),and that on E.coli was30.35+4.08%after 40 min of light treatment.The antibacterial rate increased with the increase of light intensity,time and BA content.Through SOSG detection and analysis,it is found that light treatment produces ~1O₂to kill bacteria.Compared with the control group,the cold fresh pork packaged with PVAc-BA₅coating has good fresh-keeping effect after illumination,which can effectively prolong the shelf life of pork.3.BS complex was prepared by ion exchange.Through quantitative,infrared and photosensitive antibacterial performance analysis,it is concluded that the best ratio of BS complex is BS_{(1:5,p H=7)}:200mg BBR+1g SA,p H=7.The BBR content in BS_{(1:5,p H=7)}is 15.56+1.15%.The photosensitivity of aqueous solution is stable.10^-5mol/L BS_{(1:5,p H=7)}solution was treated with light(60m W/cm~2)for7.5 min.The antibacterial rate against S.aureus was 87.13+4.72%,and the antibacterial rate against E.coli was 66.16+6.04%.The antibacterial rate increased with the increase of light intensity,time and solution concentration.SOSG detection and analysis showed that light treatment produced ~1O₂to kill bacteria.