(a) Schematic of microfluidic device used to produce the microspheres. (b) Schematic of the arrangement of syringe pumps, microfluidic device, tubing coil and UV light for the production of microspheres. Note: all tubing is level to ensure equal pressure due to height throughout system (continuous phase syringe pump shown above this level in the diagram for clarity only).
Schematic of photorheometer setup. Light is directed from the light guide to the sample via reflection in the mirror through the clear quartz upper plate.
PVA only sphere diameter as affected by surfactant with sunflower oil as the continuous phase with and without surfactant. Constant continuous flow rate of 1000 μl/min and a variable dispersed flow rate was used.
Brightfield microscopy images of (a) PVA and (b) PVA/heparin spheres.
Comparison of diameters between PVA and PVA/heparin microspheres showing that size was unaffected by the addition of heparin (p > 0.05). Error bars represent standard error of the mean for 3 batches of spheres, to show reproducibility between batches.
Size distribution curves of PVA and PVA/heparin microspheres showing very similar distributions between the PVA and PVA/heparin spheres.
Dynamic time sweep showing representative curve for PVA and PVA/heparin, showing very similar gelation profiles and final modulus. The dashed line indicates when the UV light is turned on. Arrow indicates complete gelation, i.e., plateau of modulus value. Note: G″ ranges from 0 to 100 Pa for both PVA and PVA-Hep for the entire period.
Merged Live/Dead fluorescent image (live cells green, dead cells red) with brightfield image showing L929 cells encapsulated in (a) PVA and (b) PVA-heparin microspheres 24 h after encapsulation. Scale bar is 200 μm.
Cell viability of L929 fibroblasts in PVA and PVA-Hep microspheres over 28 days. Heparin significantly increases viability over time (p < 0.05).
Compressive modulus of PVA and PVA/heparin spheres, compared to the bulk gel modulus.
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