BME.05 – Low-Cost Tangential Flow System

• Spencer Borbas
• Indy Ear
• Angela Mitevska
• Alannah Rodrigues
• Jaden Wang

Extracellular vesicles (EVs) are nano-sized particles secreted by cells for intercellular communication. Biomedical researchers have been leveraging the communicative ability of EVs for therapeutic purposes including applications in drug delivery and gene therapy. However, researchers require a method to isolate and concentrate EVs from biological solutions. Tangential flow filtration (TFF) is an effective method of filtration that can produce higher yields in lower runtimes than other methods, such as direct flow filtration and ultracentrifugation. However, most commercial TFF systems are too expensive for many research labs to purchase, costing upwards of $10,000 USD. Our Senior Design project aims to create a low-cost TFF system for biomedical researchers that want to isolate EVs for therapeutic purposes. The most important requirements for our solution were: 1) the cost of the system must be less than $500 USD, and 2) the device must be able to separate particles ranging from 50 to 200 nm in diameter from other molecules in a biological solution. To meet these requirements, our low-cost TFF system uses a peristaltic pump to drive fluid through a cyclic fluid circuit. In this circuit, there are two custom-designed filter modules connected in parallel, such that fluid can be toggled to flow through the 50 nm filter, then through the 200 nm filter to isolate the target particle range. These filters were designed and manufactured using membrane filter sheets and 3D-printed materials, reducing costs compared to commercial solutions. Verification testing involved using five batches of phosphate-buffered saline (PBS). The size distribution of particles in each batch of unprocessed PBS was quantified using a NanoSight Pro Nanoparticle Tracking Analyzer. Then, each batch of PBS was filtered using our TFF system, and the size distribution of particles in the resulting filtrates was quantified using the NanoSight Pro. A one-sided, paired t-test was used to compare the particle size distribution results of the unprocessed and processed PBS samples. Our TFF system, on average, increased the concentration of PBS particles with a diameter between 50 to 200 nm and decreased the percent composition of particles outside this range by 11.89% (p=0.0014). Our system was also built for $320, significantly less than commercial solutions. Although we conformed to the two most important design requirements, some revisions to our system are needed as foreign particles within the desired size range were introduced by our system. Our next steps to prevent contamination will include improved manufacturing methods of our custom-designed filter cassettes as well as further specifications of the lab environment needed for filtering. Research on EVs for drug delivery, gene therapies, and as biomarkers can have increased accessibility with downstream solutions such as our TFF system. Reducing time and costs allows for more experimentation with EVs and identification of new medical treatments using EVs. For validation testing, we intend on giving our device to our sponsors for testing to determine if the EVs yielded are viable and identify operational issues.