Shape-Controlled Production of Biodegradable Calcium Alginate Gel Microparticles Using a Novel Microfluidic Device

Abstract

In this paper we describe a novel method of manufacturing shape-controlled calcium alginate gel microparticles in a microfluidic device. Both manufacturing shape-controlled microparticles and synthesizing hydrogel microparticles could be performed simultaneously in the microfluidic device. The novel microfluidic device comprised of two individual flow-focusing channels and a synthesizing channel was successfully applied as a continuous microfluidic reactor to synthesize gel microparticles with size and shape control. By passive control based on the microchannel geometric confinement and liquid-phase flow rates, we succeeded in producing monodisperse sodium alginate microparticles with diverse shapes (such as plugs, disks, microspheres, rods, and threads) in the flow-focusing channels of the microfluidic device. The shape and size of the sodium alginate microparticles could be tuned by adjusting the flow rates of the various streams. Further stages of the chemical reaction could be initiated by mixing sodium alginate microparticles and calcium chloride (CaCl2) solution in the synthesizing channel. The shapes of the sodium alginate microparticles could be permanently preserved by the synthesis of calcium alginate gel microparticles. The preparation conditions of size- and shape-controlled calcium alginate microparticles and influence factors were studied.

Shape controllable microgel particles prepared by microfluidic combining external ionic crosslinking

“…For example, Zhao and the coworkers prepared microgels in the microfluidic channels by fusing the different water droplets containing CaCl 2 and sodium alginate, respectively. 21 Non-spherical microgels, such as disk-like or plug-like microgels can be obtained by adjusting the flow rates. In their strategy, crosslinking of sodium alginate occurred in the microfluidics channel, microgels with limited morphologies can thus be obtained by changing only the flow rates.…”

“…[5][6][7][8][9][10][11][12][13][14] Non-spherical microgel, such as rod-like, wedge-like, and disk-like microgels, can also be prepared via well-designed microfluidic channels or mask-photopolymerization. [15][16][17][18][19][20][21][22][23] Nowadays, it still remains a challenge for preparing more complicated microgels with controllable shapes and built-in functionalities for novel applications, which mimic those of some living micro-creatures. Recently, Sarkar and his coworkers modeled the deformation of a viscoelastic drop falling through a Newtonian medium and pointed out that viscoelasticity can make an initially spherical drop deformed into an oblate shape with a dimple at the rear end.…”

“…24 In this report, we demonstrate a facile, yet versatile strategy to prepare biomimetic alginate microgels with precisely controllable morphologies by means of a microfluidic-assisted procedure combining external ionic crosslinking. In comparison with the crosslinking occurred in the microchannels, 21 this unique external ionic crosslinking (gelation bath) allows more experimental parameters for precisely controlling of the morphology, e.g., viscosity of the gelation bath, ratio of the oil/water in the gelation bath as well as the collecting height, excepting flow rate as shown in Fig. 1.…”

Microfluidic formulation of pectin microbeads for encapsulation and controlled release of nanoparticles

“…10,24,25,28,29 Finally, in coalescence-induced gelation two aqueous droplets, one with the biopolymer and one with the ions, are coalesced to induce cross-linking. [30][31][32] Combined methods are also known. 25,26,33 These methods have their drawbacks.…”

Generation of alginate gel particles with AuNPs layers by polydimethylsiloxan template

“…Taking the great advantage of microfluidic technology, different approaches have been designed to shrink the particles to microscal. [11][12][13] Previously, we selected a template approach to fabricate anisotropic alginate microparticles with AuNPs layers. 14 Chloroauric acid ͑HAuCl 4 ͒ is usually reduced by physical or chemical method to produce AuNPs in aqueous solution.…”