Microfluidic synthesis of multifunctional Janus particles for biomedical applications

Abstract

Multifunctional Janus particles have a variety of applications in a wide range of fields. However, to achieve many of these applications, high-throughput, low-cost techniques are needed to synthesize these particles with precise control of the various structural/physical/chemical properties. Microfluidics provides a unique platform to fabricate Janus particles using carefully controlled liquid flow in microfluidic channels to form Janus droplets and various types of solidification methods to solidify them into Janus particles. In this Focus article, we summarize the most recent representative works on Janus particle fabrication in microfluidics. The applications of Janus particles in biomedical areas are emphasized. We believe that microfluidics-enabled multifunctional Janus particles could resolve multiple prevalent issues in biomedicine (e.g., disease monitoring at an early stage, high-throughput bioassays, therapeutic delivery) if persistent effort and collaboration are devoted to this direction.

Recent advances in the production of controllable multiple emulsions using microfabricated devices

“…Microfluidic emulsification devices such as planar and non-planar junctions, flow focusing devices and glass capillary devices can generate double, triple, quadruple, and quintuple multiple emulsion drops with a polydispersity in the dripping regime of less than (Higashi et al, 1999(Higashi et al, , 1995(Higashi et al, , 2000 SPG (repeated PME, n=5-6) 10.7 mm (b) Core-shell droplets (Vladisavljević et al, 2012a); (c) multiple concentric shells (Kim et al, 2011a); (d) Drops with controlled number of inner droplets (2, 3, 4, …) ; (e) High-order multiple emulsions with controlled number of droplets at each level ; (e) Core/shell droplets with numerous inner droplets ; (g) Distinct inner droplets (Wang et al, 2011); (h) Janus and ternary droplets (Yang et al, 2012;Nie et al, 2006); (i) Non-spherical Janus droplets (Shepherd et al, 2006). Figure 3.…”

“…Strictly speaking, a Janus drop should have two distinct regions on the surface of roughly equal surface area. However, the term has been expanded to include all multi-segment droplet structures with regions of different composition co-existing in asymmetric geometries (Yang et al, 2012) (Figure 1h). …”

Formation of Polymeric Hollow Microcapsules and Microlenses Using Gas-in-Organic-in-Water Droplets

“…The gas core and organic shell droplets can be changed into a Janus droplet [39,40] according to its environmental condition such as stirring, thus our process has the flexibility of altering the positioning and arrangement of the droplets by varying synthesis conditions. In our method, the density of the gas core and the organic shell materials differed greatly.…”

Ultraviolet-assisted microfluidic generation of ferroelectric composite particles

“…16 Additionally, the particles generated by dropletmicrofluidics exhibit much better uniformity in size distribution than those synthesized by traditional method. 17 Herein, we introduce a continuous generation method of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE))-copper phthalocyanine (CuPc) dielectric microparticles with different morphologies (spheres, disks, and rods) based on the droplet-microfluidic technique. P(VDFa) Author to whom correspondence should be addressed.…”