| Pickering emulsions stabilized by colloidal particles have lower dosage,higher stability,and better biocompatibility than the emulsions stabilized by surfactant.In addition,the micro/nanoparticles at the oil-water interface can bring more different functionalities to the emulsions.Compared with inorganic particles or organic synthetic particles,biological-based particles have become the focus of research in the fields of food,medicine,cosmetics,and materials due to their excellent biocompatibility,low irritation,and renewabilit.Phytoglycogen（PG）is a bio-based polysaccharide nanoparticle with excellent water dispersibility,water retention,stability,etc.,and its dendritic macromolecular structure is also conducive to loading active substances for transmembrane and transdermal delivery.Due to its suitable size and unique structure,PG has become one of the best candidates for Pickering emulsion stabilizers.However,the hydrophilic surface of PG limits its application in emulsions.Chemical grafting modification of particles is a common but cumbersome method and defeats the original intention of the use of natural biological particles.Therefore,it is very meaningful to develop a green method to hydrophobize PG without chemical modification;Based on the non-covalent interaction,this paper developed the method of physical adsorption of natural molecules on the particle surface to improve the wettability of particles,and further investigated the effects of different factors on their interaction and the stability of emulsion.Specific contents are as follows:（1）Preparation and application of Pickering emulsions synergistically stabilized by PG and CSIn this section,Pickering emulsions stabilized by all-natural PG/CS complex particles made of PG and CS was developed.The PG was coated by CS via electrostatic interaction and the interfacial activity and hydrophobicity of PC complex particles were significantly improved with the increase of CS adsorption.Compared with pure PG or CS,PC complex particles can emulsify a range of cosmetic oils with the formation of more stable and smaller emulsion droplets,and the emulsion can stable for more than 6 months.Moreover,the resulting Pickering emulsions were stable in different environments with p H（3-10）and ionic strength（400 m M）.Finally,the Pickering emulsions stabilized by PC complex particles were used as the carrier of hydrophobic actives,which can reduce the influence of ultraviolet and high temperature,and improve the bioavailability in transdermal delivery.Compared with the pure oil phase and the emulsion stabilized by surfactant（Tween 20）,the bioavailability of Pickering emulsions increased to approximately 300%and 200%,respectively.The combination of natural and edible PG with CS offers a unique prospect for emulsion systems for pharmaceuticals,food,or cosmetics.（2）Preparation and application of Pickering emulsions synergistically stabilized by PG and TAThe preparation of PC complex particles is very sensitive to p H and ionic strength,and it is difficult to stabilize vegetable oils for a long time.Therefore,PG and TA were used to prepare PT complex particles was modified by self-assembly,and the wettability of particles by physical adsorption had been further developed.Turbidity,isothermal calorimetry,FT-IR,etc.had demonstrated the existence of non-covalent interactions（hydrogen bonds）between PG and TA.The PT complex particles had more suitable surface wettability and interfacial activity indicated by the three-phase contact angle and dynamic interfacial tension.The interaction between PG and TA was revealed by examining the stability of the emulsions under different ionic strength,Urea concentration and p H value,revealing that the formation of PT complex particles is the key to the stability of Pickering emulsions.In addition,the PT complex can stabilize a series of oils,including vegetable oils,long-chain alkanes,aromatic hydrocarbons,etc.,with high stability（12 months）and salt resistance.Furthermore,the PT complex particles layer at the oil-water interface in the Pickering emulsion can provide an antioxidant interface and greatly inhibit the oxidation of lipids.Besides,utilizing the TA in the interface layer as the organic ligand,the Pickering emulsion as the template,and Fe3+as the inorganic cross-linking agent,the microcapsules were constructed to achieve the protection of hydrophobic actives,controlled release,and the sustained release of fragrances.In conclusion,the system is expected to be applied in food,pharmaceuticals and cosmetics. |
