Preparation And Study On Nanoparticle-stabilized Pickering Emulsion And Bubble

In the past decade,the Pickering emulsion and Pickering bubble have attracted considerable attention in various fields,such as chemical engineering,materials science,pharmaceutical engineering,drug delivery,and biochemistry.As well known,the emulsion or bubble can be stabilized by small molecules or some macromolecular surfactants,but some of these surfactants are highly toxic,even carcinogenic.Due to thermal motion,adsorption and desorption of molecular surfactants at the interface are under dynamic equilibrium,and the emulsions are susceptible to coalescence and Ostwald ripening,eventually leading to phase separation.The Pickering emulsion/ Pickering bubble only uses solid particles as surfactants,which directly replaces molecular surfactants in the traditional emulsion/bubble.Solid particles can be irreversibly attached directly to the oil/water interface or the gas/liquid interface,which not only inhibits the coalescence of droplets or bubbles,resulting in more efficient stability than molecular surfactant adsorption but also gives the emulsion/bubble useful properties such as pH response,electrical conductivity,porosity,etc.Some biocompatible solid particles are non-toxic and nonirritating,so that the emulsion/bubble stabilized by them has higher safety for in vivo usage.In this paper,a series of researches have been conducted on the problems of emulsion/bubble.Firstly,multi-functional integrated shellac/PLA Janus nanoparticles with controllable size and morphology,good biocompatibility and biodegradability are prepared by phase separation and coprecipitation.Then,the amphiphilic properties of Janus particles are obtained by surface hydrophilic modification,and the Pickering emulsions are prepared by using amphiphilic Janus particles as colloidal surfactants,which are very stable,pH-responsive and flexible to adjust the emulsion type.Finally,the Pickering bubble stabilized by polydopamine nanoparticles is developed through interfacial nanoprecipitation.The Pickering bubble with good dispersibility,stability,biocompatibility and biological safety can efficiently transport oxygen,improve the tumor hypoxia microenvironment and realize the treatment of tumors in combination with chemotherapeutics.It expands the application of Pickering emulsion/bubble in the field of biomedicine.The research contents and innovative achievements are described as below:(1)Biocompatible Janus nanoparticles with a shellac bulb at one end and a polylactic acid bulb at the other end are prepared by co-precipitation and phase separation using microfluidic technology.Large-scale continuous preparation of shellac/PLA Janus particles is realized by a flow-focusing microfluidic device.Then,the formation mechanism of Janus nanoparticles is explored.The particle size is mainly affected by the mixing time,and the final morphology of the particles is related to the interfacial tension of the binary polymer system.It is verified through experiments that the three-phase interfacial tension of the shellac/PLA system satisfies the relationship between the binary polymer to form the Janus structure.Janus particles have many advantages,such as anisotropic components,excellent biocompatibility,controllable particle size,controllable morphology and good dispersibility.(2)A Pickering emulsion stabilized by amphiphilic Janus nanoparticles is prepared.Amphiphilic Janus particles are obtained by surface hydrophilic modification.The Pickering emulsions stabilized by amphiphilic Janus particles as ideal particle surfactants can be stable for at least one year.In addition,Pickering emulsions have many unique properties,such as universality,pH responsiveness and emulsion type controllability.The amphiphilic Janus particles with controllable morphology can largely adjust the curvature of the water/oil interface to obtain the desired Pickering emulsion type,which expands their potential at the application in the fields of materials science,pharmaceutical engineering,drug delivery and biomedicine.(3)A Pickering micro-oxygen bubble stabilized by polydopamine nanoparticles is prepared by the interface nanoprecipitation method.The Pickering micro-oxygen bubble stabilized by polydopamine nanoparticles has good dispersion,biocompatibility and biosecurity.It is an excellent oxygen transport carrier,which can quickly increase the oxygen concentration of the anoxic solution and change the anoxic environment into an oxygen-rich environment.Besides,the micro-oxygen bubbles can improve the tumor's hypoxia microenvironment.The combination therapy of micro-oxygen bubbles and gemcitabine has shown excellent therapeutic effects in inhibiting tumor growth,which has great potential in the fields of drug delivery,tumor treatment and biomedicine.