Preparation of alginate hydrogel microparticles by gelation introducing cross-linkers using droplet-based microfluidics: a review of methods

Table 1 Internal gelation with water-soluble cross-linkers: mixing cross-linkers with Na-alginate before droplet generation

References		Trivedi et al., 2009 [48]	Zhang et al., 2006 [60]	Rondeau and Cooper-White, 2008 [39]	Present review	Present review
Droplet generation	Concentration of Na-alginate	1 wt%	0.5 wt%	0.5 wt%	0.06 wt%	0.006 wt%
	Continuous fluid	Silicone oil	Mineral oil	DMC^a	DMC^a	DMC^a
	Use of surfactant	NO	Span 80	Not mentioned	NO	NO
	Geometry	Flow-focusing	Flow-focusing	Flow-focusing	Cross-flowing	Cross-flowing
	Microfluidic material	Fluoropolymer tubing and junctions	PDMS chip	PDMS chip	Fluoropolymer tubing and junctions	Fluoropolymer tubing and junctions
Internal gelation by mixing Na-alginate and water-soluble cross-linker	Cross-linker	BaCl₂ (50 mM)	CaCl₂ (0.1 wt%)	CaCl₂ (0.25 wt%)	CaCl₂ (0.06 wt%)	CaCl₂ (0.002 wt%)
	Geometry	Flow-focusing	Cross-flowing	Flow-focusing	–	Cross-flowing
	Mixing	Before droplet generation	During droplet generation	Before droplet generation	Off-line, before droplet generation	During droplet generation

ISSN: 2055-7124