Efeito de padrões de escoamento sobre o particionamento de biomoléculas (proteína e ampicilina) em sistemas aquosos bifásicos (SABs) empregando microsistemas

Abstract

Protein separation is a complex process which involves an expensive sequence of steps. In this work, a microsystem was built to separate standard proteins using the liquidliquid extraction technique through an aqueous two-phase system (ATPS) of salt and polymer. The ATPS was formed by the mixture of the polymer polyethyleneglycol – PEG (25% w/w), potassium phosphate (10% w/w), and distilled water (65% w/w). The microsystem channels present diameters of 0.51mm, 1.14 mm and 1.8 mm. The total flow range was from 20 to 700 μL/min. Initially, flow patterns were determined using ATPS composed of PEG/phosphate with different polymer molecular masses (PEG 1500, PEG 4000 and PEG 6000) and silicone minichannels with circular geometry positioned in a senoidal form and with a 1.8 mm diameter. As expected, the gradual increase of the liquid flow allowed to reach the following flow patterns in sequence: slug flow, droplet flow and parallel flow. For the systems formed by PEG 4000/phosphate and PEG 6000/phosphate, the elevated viscosity prevented the occurence of the parallel flow. Next, was studied the effect of the flow patterns over the recovery of albumin from the bovine serum – BSA and ampicillin – for the three flow patterns was obtained in the PEG 1500/dibasic potassium phosphate at the residence times of 3, 5 and 10 min in the 1.8 mm minichannel. In this condition, the highest BSA recovery efficiencies were obtained in 10 min of residence time, with the droplet regime providing the greatest recovery rate. However, in the recovery of a smaller molecule (ampicillin), whose molar mass is 349 g/mol, it was not possible to observe significant differences between the flow patterns for the same residence time. Experiments of recovery of BSA were also done using a 1.14 mm minichannel and a 0.510 mm microchannel employing a droplet flow pattern and residence times of 3, 5 and 10 min, respectively. The reduction in the channel diameter and the increase of residence times had positive effect in the extraction efficiency and the maximum efficiency value obtained was 69% for the 0.510 mm microchannel and 10 min residence time. Furthermore, the flow pattern and scale reduction had a positive effect on the volumetric mass transfer coefficient (𝐾𝐿𝑎), with maximum values being obtained for the droplet pattern and 0.510 mm microchannel.