No abstract

A novel strategy based on droplet microfluidics is developed for facile fabrication of monodisperse poly(vinyl alcohol) (PVA) microspheres with controllable sizes and elastic properties for embolization. Monodisperse emulsion droplets are fabricated as templates by dissolving PVA and boric acid in the aqueous disperse phase, and chemical cross-linking between PVA and boric acid inside droplet templates is triggered by adding NaOH into the downstream receiving solution. The cross-linking speed and degree between PVA and boric acid inside droplet templates can be controlled by adjusting the NaOH concentration, height, and rotating speed of the receiving solution. The sizes of droplet templates and resultant cross-linked PVA microspheres can be precisely controlled by adjusting the characteristic dimensions of the microfluidic device as well as the flow rates of disperse and continuous phases. Moreover, the elastic, swelling, and drug-loading properties of PVA microspheres can be controllably regulated by adjusting the ratio of PVA to boric acid in the disperse phase. With an in vitro chip, excellent embolization performances of the fabricated PVA microspheres are visually demonstrated. The proposed strategy provides a facile and efficient route for fabricating monodisperse PVA microspheres with a controllable size and elastic, swelling, drug-loading, and drug-release properties, which are highly desired for applications in embolization therapy.

Controllable mass production of monodisperse droplets plays a key role in numerous fields ranging from scientific research to industrial application. Microfluidic ladder networks show great power in mass production of...

In this study, the effects of physico-chemical-mechanical properties of embolic microspheres on embolization performances are systematically investigated for the first time in a self-designed and 3D-printed transparent in vitro embolization chip. With droplet microfluidic devices, monodisperse poly(lactic-co-glycolic acid) (PLGA), chitosan, calcium alginate (Ca-ALG), and poly(vinyl alcohol) (PVA) microspheres with uniform shapes and controllable diameters are successfully fabricated. The embolization performances of microspheres with different physico-chemical-mechanical properties, including the elastic properties, surface adhesion properties, and sizes, are evaluated by observing the embolization positions of microspheres in the microchannels inside the chip and measuring the embolization-induced decreases of trans-channel water fluxes of the chip. The results show that for the microspheres with large Young’s moduli and low surface adhesion properties, the microchannel diameters that can be embolized by microspheres are almost the same as the corresponding microsphere diameters; however, when the microspheres have very low Young’s moduli, they can deform in the microchannels and pass through microchannels with diameters much smaller than the microsphere diameters. Generally, embolic microspheres with good elastic property, low surface adhesion property, and suitable size can achieve desired embolization performances. This work provides a new platform for controllable fabrication and performance characterization of future materials for embolization, and the results provide valuable guidance for designing efficient embolic materials for the transcatheter arterial embolization therapy.

No abstract