Droplet Microfluidics Powered Hydrogel Microparticles for Stem Cell-Mediated Biomedical Applications.

Stem cell-related therapeutic technologies have garnered significant attention of the research community for their multi-faceted applications. To promote the therapeutic effects of stem cells, the strategies for cell microencapsulation in hydrogel microparticles have been widely explored, as the hydrogel microparticles have the potential to facilitate oxygen diffusion and nutrient transport alongside their ability to promote crucial cell-cell and cell-matrix interactions. Despite their significant promise, there is an acute shortage of automated, standardized, and reproducible platforms to further stem cell-related research. Microfluidics offers an intriguing platform to produce stem cell-laden hydrogel microparticles (SCHMs) owing to its ability to manipulate the fluids at the micrometer scale as well as precisely control the structure and composition of microparticles. In this review, the typical biomaterials and crosslinking methods for microfluidic encapsulation of stem cells as well as the progress in droplet-based microfluidics for the fabrication of SCHMs are outlined. Moreover, the important biomedical applications of SCHMs are highlighted, including regenerative medicine, tissue engineering, scale-up production of stem cells, and microenvironmental simulation for fundamental cell studies. Overall, microfluidics holds tremendous potential for enabling the production of diverse hydrogel microparticles and is worthy for various stem cell-related biomedical applications.

Copper-Consuming Nanoplatform for Alleviating Hypoxia and Overcoming Resistance to Sonodynamic Therapy of Breast Cancer.

Sonodynamic therapy (SDT) is a promising treatment modality for breast cancer; however, its effectiveness is often impeded by the hypoxic tumor microenvironment owing to an insufficient oxygen supply in the solid tumors. To overcome this challenge, we elaborately developed a 4T1 tumor-targeted multifunctional nanoagent by integrating both dendrimer-structured copper chelating agents and organic sonosensitizers (IR820) into a biotin-modified nanoliposome via a microfluidic-assisted self-assembly. In particular, the aforementioned copper chelating agent was constructed by introducing multiple xanthate groups into a dendrimer polymer, which showed a significant selectivity for the consumption of the intracellular copper levels. Based on this, the nanoliposome-based therapeutic not only disrupted the activity of the mitochondrial complex IV to directly inhibit the tumor cell proliferation but also suppressed the resistance to the SDT via inhibition of the oxygen consumption for cellular respiration. Both in vitro and in vivo studies confirmed that the designed nanoagents exhibit a synergistic tumor inhibition effect of copper consumption and IR820-mediated SDT. Taken together, this approach establishes a proof-of-concept for the construction of a copper-ion-modulated nanomedicine to significantly enhance the efficiency of oxygen-dependent cancer treatments.

Morphology Control of Electrospun Brominated Butyl Rubber Microfibrous Membrane.

Brominated butyl rubber (BIIR) is a derivative of butyl rubber, with the advantage of high physical strength, good vibration damping performance, low permeability, aging resistance, weather resistance, etc. However, it is hard to avoid BIIR fiber sticking together due to serious swelling or merging, resulting in few studies on BIIR electrospinning. In this work, brominated butyl rubber membrane (mat) with BIIR microfiber has been prepared by electrospinning. The spinnability of elastomer BIIR has been explored. The factors influencing the morphology of BIIR microfiber membranes have been studied, including solvent, electrospinning parameters, concentration, and the rheological property of electrospinning solution. The optimal parameters for electrospinning BIIR have been obtained. A BIIR membrane with the ideal microfiber morphology has been obtained, which can be peeled from aluminum foil on a collector easily without being broken. Anti-bacterial property, the electrical conductivity of these membranes, and the mechanical properties of these samples were studied. The optimized BIIR electrospinning solution is Bingham fluid. The results of these experiments show that a BIIR membrane can be used in the field of medical prevention, wearable electronics, electronic skin, and in other fields that require antibacterial functional polymer materials.