An ATPS-based droplet microfluidic device for protein partitioning Academic Article in Scopus uri icon

abstract

  • Background: Droplet microfluidics uses immiscible phases to manipulate discrete volumes inside microchannels, and it is applied in synthesis of biomolecules, encapsulation, drug delivery and cell analysis. The use of aqueous two-phase systems (ATPS) is a strategy for the fractionation of biomolecules. Here, we combined both techniques to fabricate a microfluidic device based on a polymer¿salt ATPS, composed of polyethylene glycol (PEG) 8000 and phosphate salt buffer (PO4), capable of generating droplets and partitioning red fluorescent protein (RFP), used as a model of study. Partition behavior, droplet size and frequency were characterized, employing a polydimethylsiloxane microdevice for this purpose. Results: The microdevice exhibited either a two-phase or droplet behavior in the absence and presence of RFP. In both scenarios, the model protein was partitioned towards the salt-rich phase (PO4), as in traditional ATPS. In addition, by controlling fluid velocity, different regimes of droplet formation were observed, i.e. dripping and jetting. RFP was partitioned and encapsulated in both regimes. The microdevices exhibited a partition coefficient, (Formula presented.), of 0.34 ± 0.016, which is comparable with that obtained in traditional systems ((Formula presented.) = 0.39 ± 0.012). Droplet size diminished as (Formula presented.), (Formula presented.), increased. Droplet breakup time has the same effect when increasing velocity ratio, while frequency of droplet formation increased. COMSOL computational simulations were performed, exhibiting good agreement with experimental results. Conclusion: The microfluidic device proved to be a useful platform to generate droplets by using polymer PEG¿salt ATPS under controlled conditions. Besides, it allowed partitioning and encapsulation of the model protein. This microfluidic platform presents a viable alternative for protein separation and encapsulation, which can further support high-value-biomolecule separation. © 2025 Society of Chemical Industry (SCI). © 2025 Society of Chemical Industry (SCI).

publication date

  • January 1, 2025