Facile fabrication of drug-loaded PEGDA microcapsules for drug evaluation using droplet-based microchip

Droplet-based microfluidic technology can be utilized as a microreactor to prepare novel functional monodisperse microcapsules.In this study,a droplet-based microfluidic chip with surface modification,which allowed the one-step preparation of double emulsion microcapsules.An O/W/O double emulsion using polyethylene(glycol)diacrylate(PEGDA)solution as the intermediate water phase was prepared by regulating the hydrophilicity and hydrophobicity of the chip surface,with PEGDA microcapsules prepared using UV polymerization.And then anti-tumor drug paclitaxel and neurotoxin 6-OHDA were encapsulated in microcapsules for drug and toxicology evaluation,respectively.Compared to controls,drug-loaded mi-crocapsules caused a significant increase in the death rate of PC12 cells.This indicates that the obtained drug-loaded microcapsules could be used in drug evaluation and potentially in drug screening and deliv-ery.

A nano-liter droplet-based microfluidic reactor serves as continuous large-scale production of inorganic perovskite nanocrystals

Lead halide perovskite nanocrystals(NCs)exhibit high photoluminescence quantum yield(PLQY),high defect tolerance,narrow half peak width,and wide luminous gamut,making them the ideal optoelectronic materials in numerous fields.Nonetheless,their production still suffers from the limited productivity at the bench level.In this work,we fabricated CsPbX3(X=Cl,Br,I)NCs within droplet-based micro-reactors,where both the nucleation and growth processes could be precisely controlled inside 130-nL microdroplets.This provides a new paradigm for the large-scale synthesis of perovskite NCs with high PLQY.Compared with other synthetic methods,this method can increase the concentration of reactant precursors by 3±116 times,while lowering the ligand to reactant ratio to 2%±50%of the commonly used hot-injection method.By modulating the reaction temperature and residence time,the structure-function relationship between the morphology of NCs and PL properties was extensively investigated.The microfluidic-based process allows the flexible adjustment in the proportion of PbX2 precursors to achieve the fabrication of perovskite NCs whose luminescence range covers the entire visible spectrum(406±677 nm)within one reaction.Finally,perovskite NCs with different halide ions were encapsulated in polymethyl methacrylate to prepare a colored light-emitting diode strip.

Development of 3D bioprinting:From printing methods to biomedical applications

Biomanufacturing of tissues/organs in vitro is our big dream,driven by two needs:organ transplantation and accurate tissue models.Over the last decades,3D bioprinting has been widely applied in the construction of many tissues/organs such as skins,vessels,hearts,etc.,which can not only lay a foundation for the grand goal of organ replacement,but also be served as in vitro models committed to pharmacokinetics,drug screening and so on.As organs are so complicated,many bioprinting methods are exploited to figure out the challenges of different applications.So the question is how to choose the suitable bioprinting method?Herein,we systematically review the evolution,process and classification of 3D bioprinting with an emphasis on the fundamental printing principles and commercialized bioprinters.We summarize and classify extrusion-based,dropletbased,and photocuring-based bioprinting methods and give some advices for applications.Among them,coaxial and multi-material bioprinting are highlighted and basic principles of designing bioinks are also discussed.

Mechanisms of rectangular groove-induced multiple-microdroplet coalescences

The mechanism of microdroplet coalescence is a fundamental issue for droplet-based microfluidics. We developed an asymmetric expansion (a rectangular groove) along one side of a microchannel to achieve multiple-microdroplet trapping, collision, and coalescence. Compared with reported symmetric expansions, this asymmetric groove could easily trap microdroplets and control two or three microdroplet coalescences precisely without a requirement for temporal and spatial synchronization. To reveal the mechanisms of multiple-droplet coalescences in a groove, we observed five different coalescence patterns under different flow conditions. Moreover, we characterized the flow behavior quantitatively by simulating the velocity vector fields in both the microdroplets and continuous phase, finding good agreement with experiments. Finally, a map of coalescence forms with different capillary numbers () and flow ratios () was obtained. The results could provide a useful guidance for the design and application of droplet-based microfluidic devices.

Advanced Biotechnology for Cell Cryopreservation

Cell cryopreservation has evolved as an important technology required for supporting various cell-based applications,such as stem cell therapy,tissue engineering,and assisted reproduction.Recent times have witnessed an increase in the clinical demand of these applications,requiring urgent improvements in cell cryopreservation.However,cryopreservation technology suff ers from the issues of low cryopreservation effi ciency and cryoprotectant(CPA)toxicity.Application of advanced biotechnology tools can signifi cantly improve post-thaw cell survival and reduce or even eliminate the use of organic solvent CPAs,thus promoting the development of cryopreservation.Herein,based on the diff erent cryopreservation mechanisms available,we provide an overview of the applications and achievements of various biotechnology tools used in cell cryopreservation,including trehalose delivery,hydrogel-based cell encapsulation technique,droplet-based cell printing,and nanowarming,and also discuss the associated challenges and perspectives for future development.

From Droplets and Particles to Hierarchical Spatial Organization： Nanotechnology Challenges for Microfluidics

The compartimentation of fluids in the microliter, nanoliter and picoliter range leads recently to many applications of microfluidics in material development, diagnostics and biological screenings. Droplet-based microfluidics allows the improvement of nanoparticle homogeneity and the tuning of particle properties. It supports combinatorial synthesis of inorganic as well as organic substances and can be applied for the cultivation and screening of bacteria, eucaryotic cells and fish embryos. The well-ordered handling and the addressing of microfluid segments improves the information transfer between chemical, biological and electronic systems. Despite this remarkable technical progress, there is a particular importance of microfluidics for future nanotechnological solutions. The hierarchical spatial organization of liquids, particles and gels in microfluidics represents a fundamental biomimetic principle which overcomes the limits of planar technology and opens the gate for realizing complex structured threedimensional nanoarchitectures. Recent applications of microstructured fluids in chemistry and biology and concepts for future developments will be discussed.