Sub Topic | Secondary Topic: Biotherapeutics and Biotechnology - Bioassay | Potency
Authors: Julian Alberni, Neofluidics, LLC (Presenting Author); Connor Sullivan, Neofluidics, LLC; Yadir Guerrero, Neofluidics, LLC; Deepak Solomon, Neofluidics, LLC; Chandrasen Soans, Neofluidics, LLC; Nilesh Gupta, Neofluidics, LLC (Main Author)
Presenting Author: Julian Alberni
Purpose: Droplet manipulation of precise and measurable volumes opens numerous avenues for both biological assays and pharmaceutical testing. A few of these benefits are reduction in cost, less reagent/sample volume, and quicker assays. Furthermore, droplet manipulation at nanoliter scale affords the ability to do large scale multiplexing that could conceivably be used for applications like library prep for next-generation sequencing.,. The current work aims to integrate droplet fusion, fission, and mixing capabilities onto one microfluidic device, NeoFUSION™, therefore mitigating chances for contamination, reducing processing time, and reducing cost.
Methods: A microfluidic droplet manipulation device was designed and fabricated using soft lithography techniques in polydimethylsiloxane (PDMS). First, droplet fusion capability was optimized using solutions of food dyes in distilled water to ensure complete merging of the trapped contents. Further, similar experiments were performed using gradients of glycerol, and different buffer solutions to verify that viscosity and surface tension didn’t change the efficacy. Next, the mixing feature was tested using colored dyes and acid/base pH tests. Finally, to validate that the devices could split a perfectly merged daughter droplet, we placed two equally sized traps downstream and performed trapping of the daughter droplet into two equal volume droplets. A stereo microscope was used to acquire images and analysis was performed using ImageJ software. All the above-mentioned operations were carried out using off-the-shelf manual and electronic pipettes at different flow rates (low-to-high) and volumes ranging from 1-10 microliters.
Results: Droplet fusion, mixing, and splitting were investigated in the NeoFUSION™ device. Results demonstrate that droplet fusion is successful for deionized water, 50% glycerol water solution, and biological assay buffers (Figure 1). Bright field images show two primary colors being merged into a daughter droplet where diffusion begins to occur. The resultant droplet is then passed through the mixing chamber ensuring complete mixing of the daughter droplet, which further splits into two equal nanoliter volume droplets in the fission traps.
Conclusion: The present study demonstrates the all-in-one ability of NeoFUSION™ to merge, mix, and split droplets on-chip while maintaining measurable nanoliter volumes without the use of an oil phase or precise pipetting systems. The ability to perform these tasks on one chip enables both biological assays and pharmaceutical testing to be more cost effective, less time consuming, and minimizes chances of contamination. The novel design ensures consistent results regardless of pipetting speed, volume, and solution properties. Further qualitative and quantitative studies are currently being optimized for use in this device, including anti-drug antibody testing, immunoassays, turbidimetric assays, and precipitation studies.
See attached abstract pdf for images.