Microfluidic Fabrication Of Anisotropic Microspheres And Their Applications In Bioanalysis

Microfluidics is a technology to integrate different fluid phases in a microscale system,and to manipulate them systematically.With several decades of development,microfluidics has been providing novel solutions to many scientific and technical fields,including chemical synthesis,bio-chemical analysis,point-of-care-test(POCT),drug development,environment screening,etc.Especially for materials fabrication,microfluidic technology enabled accurate control over materials morphology and composition.Multiplex bio-analysis plays an important role in biomedical engineering,and suspension array-based bioassays possess obvious superiority.A key step in suspension array is to construct suitable encoding carriers.Conventional carriers,for example,polymer microspheres,exhibit isotropic surface structure and composition.However,theoretical and experimental researches indicate that anisotropic microspheres provide more functionalities than isotropic ones.Therefore,in this dissertation,we employ microfluidic technology to fabricate several kinds of anisotropic microspheres with different functions,and explore their applications in bio-analysis.The detail works are as follows:(1)Based on single emulsion system,Janus particles were fabricated with anisotropic photonic band gap(PBG)structure and magnetically controllable motion ability,through phase separation and nanoparticles self-assembly in microfluidic droplet templates.The resultant particles enabled optical encoding and magnetically controllable motion,which made them functional barcode particles in biomedical applications.(2)Based on double emulsions system,a novel microfluidic device was constructed by inserting an annular capillary array into a collection channel for single-step emulsification of double emulsions.By inserting multiple inner-phase solutions into the capillary array,multicomponent double emulsions and microcapsules with inner droplets of different contents were also obtained from the device.(3)Based on double emulsions system,a cavitation process was found in solid microcapsules with a membrane shell and a liquid core.By simply treating these microcapsules with hypertonic solutions,cavitation could be controllably triggered without special equipment or complex operations.A cavitation-formed vapor bubble was fully entrapped within the microcapsules,thus providing an facile method for fabricating encapsulated microbubbles with controllable dimensions and functional components.Then,a novel suspension array was developed using photonic crystal(PhC)microbubbles as barcode particles,which were achieved by cavitation-derived self-assembly of colloidal nanoparticles in semipermeable solid microcapsules.As the size of the encapsulated bubbles could be tailored,the overall density of the PhC microbubbles could be adjusted to match the density of a detection solution.Therefore,the PhC bubbles could remain in suspension.This feature,together with additional remarkable properties,made the PhC microbubbles excellent barcode particles.(4)Based on the composite single emulsion-double emulsions system,spindle shaped microcarrier arrays were generated and strung on the microfibers.The resultant microcarriers could be immobilized or slip on the fibers,and thus were very flexible.Moreover,the distinctive structures endowed the arrays with specific wettability features and water-capture ability.