Passive microinjection within high-throughput microfluidics for controlled actuation of droplets and cells

Abstract

Microinjection is an effective actuation technique used for precise delivery of molecules and cells into droplets or controlled delivery of genes, molecules, proteins, and viruses into single cells. Several microinjection techniques have been developed for actuating droplets and cells. However, they are still time-consuming, have shown limited success, and are not compatible with the needs of high-throughput (HT) serial microinjection. We present a new passive microinjection technique relying on pressure-driven fluid flow and pulsative flow patterns within an HT droplet microfluidic system to produce serial droplets and manage rapid and highly controlled microinjection into droplets. A microneedle is secured within the injection station to confine droplets during the microinjection. The confinement of droplets on the injection station prevents their movement or deformation during the injection process. Three-dimensional (3D) computational analysis is developed and validated to model the dynamics of multiphase flows during the emulsion generation. We investigate the influence of pulsative flows, microneedle parameters and synchronization on the efficacy of microinjection. Finally, the feasibility of implementing our microinjection model is examined experimentally. This technique can be used for tissue engineering, cells actuation and drug discovery as well as developing new strategies for drug delivery.

Rapid and Highly Controlled Generation of Monodisperse Multiple Emulsions via a One-Step Hybrid Microfluidic Device

“…Our ME formation microfluidic system requires partial hydrophilicity at a specific portion of the fluidic network to control the contact angle for generating stable MEs. Here in our model, the contact angle is modeled as the static contact angle, according to the model of drop shape analyzer device reported somewhere else 56 . Also, we used the validated algorithm of Afkhami & Bussmann 106,107 for applying the contact angle in the numerical method.…”

“…The micro-scale characteristics of the flows in microchannels enable to apply a high shear stress to the flowing fluids. The shear stress is applied on a small fraction of the fluid, as several nanoliters, which makes the size of droplet precisely adjustable 54–56 for the production of single emulsions 57,58 , multicore emulsions 59 as well as entrapment and transportation of desired particles 60–63 , cells 64–70 and bacteria 71 . Also, surface tension is dominant in micro-scale channels that allows to produce high-throughput droplets with identical size 72 and shape 2,73,74 .…”

Phospholipid membrane formation templated by coacervate droplets

“…32, 63 Microfluidic approaches offer excellent encapsulation and vesicle-to-vesicle homogeneity but require specialized methods and equipment. 64, 65 Here, we evaluate macromolecule encapsulation in membrane-coated coacervates as a very simple alternative to loading by traditional vesicle hydration. We used 0.05 μM final concentration of U15 and BSA in the solution with and without PDADMAC/PAA coacervates (Figure 6).…”

Divide and conquer: analytical chemistry of nucleic acids in droplets

“…(d) 液滴注入技术. 在瞬时电压下, 液滴表面发生瞬时变化 从而与上方注入的水相短暂融合, 后再流动推动下分开 [42] (网络版彩图) Figure 2 Microfluidic techniques applied in some biochemical reactions. (a) Digital quantification of nucleic acids.…”

“…(c) In-chip droplet selection: droplets passing by are detected and triggers electrodes to divert its direction [41]. (d) Droplet injection: under a voltage pulse, droplet surface undergoes sudden change so that merges to the liquid blow and soon get pushed away by the flow [42]…”