| In recent years,organic-inorganic hybrid nanoflower structures have attracted much attention because of their high specific surface area,excellent catalytic performance and high transport capacity.Tea polyphenols have good biocompatibility,antioxidant synergy,rich natural reserves and structural types.The construction of hybrid nanoflowers based on tea polyphenols for the delivery of food bioactive ingredients is of great significance to improve their stability and bioavailability.At the same time,with the rapid development of computer technology,application of powerful computer image recognition technology to deeply dig the color information of thin layer chromatography(TLC)image can make full use of traditional TLC.Combined with its fast and convenient characteristics,it can be used as a powerful tool for the preliminary analysis of food bioactive ingredients during loading and controlled releasing process.In this paper,a series of tea polyphenols-metal hybrid nanoflower carriers were constructed by coordination assembly,and the formation mechanism was also explored.The nanoflower carriers could respond to p H and photothermal stimulations,and realized the controlled release of different categories of food bioactive ingredients.In order to achieve the rapid analysis of loading and releasing process of the carriers,an analysis method of food bioactive ingredients based on TLC image recognition was established.The main content and results of this research can be concluded as follows:(1)An analytical method of food bioactive ingredients was established based on TLC image recognition,being used for exploration the loading and controlled releasing process of food bioactive ingredients later.After spotting,development,and visualization,the concentration and structure information of food bioactive ingredients would be transformed into the gray value and color on TLC image.The quantification and structure classification of food bioactive ingredients could be realized by using computer technology to recognize and process TLC image.The overall performance of the method is evaluated,and the reaction sites and the formation process of color products during the visualization process were explored.(2)Tea polyphenol-Cu and tea polyphenol-Zn hybrid carriers with nanoflower structure were prepared and selected through coordination interaction,and the loading capacity of Cu-based nanoflower for hydrophilic food bioactive ingredients was analyzed by TLC image recognition method.After polymerization,tea polyphenol was coordinated with Cu and assembled into nanoflower,and the importance of metal phosphate for nanoflower assembly was confirmed during the optimization process.Tea polyphenol-Cu nanoflower has petal like porous structure,and it was generally effective for the loading of flavone or flavonol glycoside and saccharides,flavone,and polyphenols in lotus leaf extract.Also,the carrier has a certain selectivity due to the different affinity of organic components to various categories of bioactive ingredients,the order of loading capacity from high to low was: polyphenols> flavone> flavone or flavonol glycoside and saccharides.(3)The lipophilic palmitoyl side chain was introduced into tea polyphenol to prepare tea polyphenol palmitate(TPP)-Cu nanoflower carrier for hydrophobic food bioactive ingredients.And the molding mechanism of TPP-Cu nanoflowers and their loading,p H responsive controlled releasing of curcumin were studied.The results suggested that polyphenol polymers could coordinate with metal ions,providing sites for the nucleation and growth of metal phosphates.It could also induce the growth and assembly of petals to form the nanoflower structure.Hydrophobic effect and steric hindrance of esterified tea polyphenols hindered the further polymerization,and the rigid molecules made the assembly process faster through skipping the nano hyperbranched stage.The hydrophobic pockets on the surface of nanoflower realized the efficient loading of curcumin(61.7 wt%),and improved UV stability and thermal stability of the carrier combined with the antioxidant effect of TPP.At the same time,the coordination bond would response to low p H and break,so as to realize the rapid release of curcumin,a gastric disease protector,in the stomach.(4)Based on the structural adjustability of the selected Zn-based nanoflowers,EGCG-Zn nanoflowers were prepared by using tea polyphenol monomer epigallocatechin gallate(EGCG).The structural regulation pattern was clarified according to the molding mechanism of nanoflower,and the release behavior of the loading guest was controlled by the relationship between structure and photothermal effect.The use of EGCG monomer could simplify the analysis of the polymerization process of tea polyphenols and show the structural regulation pattern more clearly.Results suggested that the assembly structure of the nanoflower under different conditions could be modulated by the number of coordination or nucleation sites and the relative amount of organic/inorganic components.The existence of disordered nano petals and submicron size channels affected the scattering,reflection and absorption of incident light,so structural complexity degree is the main factor affecting the photothermal effect of EGCG-Zn nanoflower.OPC and m PEG were self-assembled to the surface of EGCG-Zn nanoflower through hydrogen bond interaction,and a photothermal responsive release system was constructed.The real-time analysis by TLC image recognition demonstrated that OPC could achieve zero order release in alkaline medium due to the unique release mechanism and the narrow molecular weight distribution of m PEG,and EGCG-Zn nanoflowers with different photothermal effect could regulate the release rate of OPC.The exploration of tea polyphenol-metal hybrid nanoflower carriers and its molding mechanism in this paper has certain reference significance for the construction of hybrid carrier using other small organic molecules.Furthermore,TLC category analysis combined with image recognition also provides a way to introduce computer technology to revolutionize the traditional analytical methods. |
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