Polyethylene Glycol Aqueous Two-phase Systems Research Articles

Electric field driven addressing of ATPS droplets in microfluidic chips

The possibility of controlled droplet motion (droplet addressing) mediated by DC electric field in aqueous two-phase systems (ATPS) is here reported for the first time. Three ATPS of polyethylene glycol (PEG)/salt type, namely PEG/phosphate, PEG/sulphate, and PEG/carbonate, were selected for this study. We observed fast motion of salty droplets dispersed in PEG continuous phase induced by electric field of relative low strength. Hence, three fluidic systems with separated electrode chambers for the evaluation of electrophoretic mobilities and for addressing experiments were fabricated. Electrophoretic mobilities of salty droplets always exceeded the value of $$1\times 10^{-7}\, \hbox {m}^2\hbox {V}^{-1}\hbox {s}^{-1}$$ , which is about by one magnitude higher value than those typically measured in water–oil droplet systems. The electrophoretic mobilities in systems with free surface are the same or even smaller than in closed microfluidic structures, which is accounted mainly to the fact that a significant part of salty droplets is exposed to air and does not contribute to droplet forcing. Series of addressing and merging experiments in a microfluidic chip shows that DC electric field can be used as a powerful tool for smart manipulation of droplets in microfluidic systems with PEG/salt ATPS.

Design of a microfluidic platform for monoclonal antibody extraction using an aqueous two-phase system

The use of monoclonal antibodies (mAbs) in medical treatments and in laboratory techniques has a very important impact in the battle against many diseases, namely in the treatment of cancer, autoimmune diseases and neural disorders. Thus these biopharmaceuticals have become increasingly important, reinforcing the demand for efficient, scalable and cost-effective techniques for providing pure antibodies. Aqueous two-phase systems (ATPS) have shown potential for downstream processing of mAbs. In this work, an ATPS in a microfluidic platform was designed and tested for mAbs extraction. The system demonstrated the potential to be an effective tool to accelerate bioprocess design and optimization. The partition of immunoglobulin G (IgG) tagged with fluorescein isothiocyanate (FITC) in an ATPS of polyethylene-glycol (PEG)/phosphate buffer with NaCl was investigated using a PDMS microfluidic device fabricated using soft lithography techniques. Different structures were tested with different values of microchannel length (3.14–16.8cm) and flow rates of the salt (1–2μL/min) and PEG-rich phases (0.2–0.5μL/min). A stable interphase between the phases was obtained and the phenomena of diffusion and of partition of the IgG from the salt-rich phase to the PEG-rich phase were measured by fluorescence microscopy. Process simulation allowed the modeling of the IgG diffusion and partitioning behavior observed in the microstructure. The reduction to the microscale does not greatly affect the antibody extraction yield when compared with macroscale results, but it does reduce the operation time, demonstrating the potentiality of this approach to process optimization.

Aqueous two-phase extraction and polyelectrolyte precipitation combination: A simple and economically technologies for pepsin isolation from bovine abomasum homogenate

The combination of two bioseparation techniques, partition in aqueous two-phase systems and polyelectrolyte precipitation of the target enzyme from the phase where it is present, was assayed to purify pepsin from bovine abomasum homogenate. Pepsin was partitioned in favor of the polyethyleneglycol-rich phase in an aqueous two-phase system of polyethyleneglycol 600 and 1450-sodium phosphate; however, a great amount of impure proteins were present. Chitosan (a cationic natural polyelectrolyte) was added to precipitate this acid enzyme as a form of insoluble complex. The addition of this second step increased the purity of the enzyme significantly while the yield was not significantly decreased. The combination of both partition in polyethyleneglycol 1450-phosphate system and chitosan precipitation produced a pepsin recovery of 48.5% with a purification factor of 9.0. The biological activity of the recovered enzyme remained unaltered.

Purification of an α-amylase inhibitor in a polyethylene glycol/fructose-1,6-bisphosphate trisodium salt aqueous two-phase system

A novel aqueous two-phase system of polyethylene glycol (PEG)/fructose-1,6-bisphosphate (FBP) trisodium salt was employed to purify an α-amylase inhibitor (α-AI) from wheat flour after failure in use of the conventional aqueous two-phase systems of PEG/(NH 4) 2SO 4 and PEG/dextran (DEX). Phase compositions including PEG molecular weight and concentration of PEG, fructose-1,6-bisphosphate trisodium salt concentration, as well as pH of the system affected the partition of α-AI. The inhibitor was obtained with a purification factor of 3.2 and recovery of 79% by using 11.7% (w/w) of PEG2000 and 19% (w/w) of fructose-1,6-bisphosphate trisodium salt at pH 7.0 in the top phase.