Surfactant additives for digital microfluidic devices for high protein content droplets transport
Disclosed herein is a surfactant additive, ethylenediamine tetrakis(ethoxylate-block-propoxylate) tetrol with 16 ethylene oxide repeat units and 18 propylene oxide repeat units (known by its trade name as Tetronic 90R4) used as a droplet-additive, or to coat DMF driving electrode surfaces which dramatically improves the capability to work with high-protein-content liquids (e.g., whole blood) on digital microfluidic chips. This surfactant prevents protein adsorption and fouling of DMF electrode surfaces to an extent that was heretofore impossible. Specifically, this surfactant allows for the manipulation of droplets of undiluted whole blood for >1 hour per electrode (>1 50 times better than what is possible for any known additive). This improvement in handling high protein content media will revolutionize blood-based diagnostics on digital microfluidic platforms.
1 . A system for processing droplets of a fluid containing proteins, the system comprising:
an array of digital microfluidic electrodes; and
a surfactant disposable to the array of digital microfluidic electrodes,
wherein the surfactant, when disposed to the array, forms a shielding layer at an interface of surfaces of the digital microfluidic electrodes and droplets of the fluid to resist the adsorption of proteins to the digital microfluidic electrodes,
wherein a molecular arrangement of the proteins is unchanged by a presence of the surfactant,
wherein a molar ratio of the surfactant and the proteins is below 1:1,
wherein the system is configured to introduce the droplets of the fluid to the surfactant, and
wherein the surfactant has a formula as follows:
wherein:
x is an integer in a range from 4 to 32, and y is an integer in a range from 2 to 36,
m is an integer of 4 or 6
n is an integer of at least 2,
X, Y and Z are any one of the following groups:
and
W is any one of
2 . The system of claim 1 , wherein the surfactant is coated to at least a portion of the array of digital microfluidic electrodes prior to introduction of the droplets of the fluid to the array of digital microfluidic electrodes.
3 . The system of claim 1 , wherein the droplets of the fluid and the surfactant are mixed prior to introduction of the droplets of the fluid to the array of digital microfluidic electrodes.
4 . The system of claim 1 , wherein the surfactant is a copolymer that comprises a hydrophilic chain and a hydrophobic chain, wherein the hydrophilic chain is polyethylene oxide (PEO) and the hydrophobic chain is polypropylene oxide (PPO).