Fabrication Of Multi-compartmental Microspheres Using Gas-shearing Strategy And Its Applications

Multi-compartmental microspheres(MCM)have attracted considerable attention in the fields of biomedical engineering and materials science because they can carry multiple materials simultaneously in a single microsphere.MCM has been proposed to be used in the fields of multidrug release,cell co-culture,micro-motors,multi-target detection,and so on.Several technologies have been developed to fabricate compartmentalized particles,including sputtering deposition technology,emulsion method,microfluidic technology,electrospray method,and other methods.Among these methods,Recently,microfluidic technology has been extensively explored to fabricate MCMs,as it allows the highest control over the morphology and complexity of particles.However,a serious restriction of microfluidic technology often comes when sensitive biological molecules have to be encapsulated in MCMs,since the use of oils,photoinitiators,crosslinkers,surfactants,and UV-irradiation is inevitably required.To overcome these limitations,strenuous efforts including centrifugation-based methods,multiplex coaxial flow focusing,and in-air microfluidics have been explored to fabricate MCMs for biomedical purposes.Despite this,fabricating such ‘‘biofriendly'' MCMs with a super compartmentalized and controllable morphology in a one-step,green,and high-throughput process remains challenging.We pioneered a green preparation method for preparing bio-based MCM with a gas-shearing and oil-free strategy.Besides,a series of bio-based(mainly including cellulose derivatives)MCM was prepared by using bio-based materials with excellent characteristics such as green,environmentally friendly,renewable raw materials,and biodegradable as raw materials.The method established in this study to prepare anisotropic microspheres using the gas-shearing strategy can successfully achieve the preparation of up to ten compartmental microspheres.The multi-faced anisotropic microspheres show ultra-high biocompatibility,which can not only realize the co-culture of multiple cells but also construct magnetic micro-robots and anti-counterfeiting coded microspheres.They have important application value in the fields of biomedicine and materials science.The main research content and results are as follows:(1)First,a simple one-step and oil-free process,based on the gas-flow-assisted formation of microdroplets(‘gas-shearing'),is established for the scalable production of monodisperse MCMs.By changing the configuration of the needle system and gas flow in the spray ejector device,the oil-free gas-shearing process easily allows the design of microparticles consisting of two,four,and even six compartments with precise control over the properties of each compartment.As oils and surfactants are not used,the gas-shearing method is highly cytocompatible.The size of the microspheres can be controlled between tens to hundreds of micrometers with good monodispersity.Moreover,by increasing the flow rate of the polymer solution,the production scale of microspheres can be easily expanded.Besides,this strategy can not only suitable for the fabrication of water-soluble polymers but also organic-soluble polymers,which interpret the versatility of the gas-shearing approach.This research suggests that the oil-free gas-shearing strategy is a reliable,scalable,and biofriendly process for producing MCMs that may become attractive materials for biomedical applications.(2)Based on the gas-shearing strategy,to expand the application of multi-faced and different oriented biomaterial microspheres in the field of cell co-culture,we have successfully constructed eight kinds of cell co-culture models.Firstly,the biocompatibility of the microsphere carrier prepared by the gas shear strategy was evaluated.The results showed that the microsphere carrier had high biocompatibility.Even after 7 days,the cell viability remained as high as 91%.Furthermore,we have successfully prepared microspheres containing two kinds of cells,four kinds of cells,six kinds of cells and even eight kinds of cells.The eight-faced gel microspheres prepared by gas-shearing strategy can be used for 3D co-culture of cells,which laid the foundation for studying the complex interactions between cells.(3)Inspired by the natural microbial swimming,artificial micro-/nanomotors can imitate the functions of these characteristic natural systems.So far,significant efforts have been invested in developing functional micromotors.However,their applications are still hindered more or less because the using of organic solvents,photoinitiators,chemical crosslinkers,surfactants,ultraviolet irradiation,and/or cytotoxic reagents is inevitable in most fabrication processes.Herein,a simple,flexible,biocompatible,and high-throughput gas-shearing strategy is presented for fabricating designable multi-faced microspheres as aqueous micromotors with autonomous movement capacities.The fabricated micromotors consist of biocompatible sodium alginate and can be propelled by magnetic guidance or biocatalyst-mediated fuel decomposition.The motion of the micromotors may be controlled by altering their structures through changing material composition,or specifically,magnetic nanoparticle and catalyst distributions within the microspheres.The microspherical micromotors are remarkably designable,thereby resulting in a series of complex motions such as pirouette motion,linear motion,tumbling motion,curvilinear motion,and circular motion.Our results confirm the potential capability of the microspherical micromotors for widespread biomedical applications.(4)Barcodes have attracted widespread attention,especially for the multiplexed bioassays and anti?counterfeiting used toward medical and biomedical applications.An enabling gas?shearing approach is presented for generating 10?faced microspherical barcodes with precise control over the properties of each compartment.As such,the color of each compartment could be programmatically adjusted in the 10?faced memomicrospheres by using pregel solutions containing different combinations of fluorescent nanoparticles.During the process,three primary colors(red,green,and blue)are adopted to obtain up to seven merged fluorescent colors for constituting a large amount of coding as well as a magnetic compartment,capable of effective and robust high?throughput information?storage.More importantly,by using the biocompatible sodium alginate to construct the multicolor microspherical barcodes,the proposed technology is likely to advance the fields of food and pharmaceutics anti?counterfeiting.These remarkable properties point to the potential value of gas?shearing in engineering microspherical barcodes for biomedical applications in the future.