Membrane-Based, Sedimentation-Assisted Plasma Separator for Point-of-Care Applications

Abstract

Often, high sensitivity, point of care, clinical tests, such as HIV viral load, require large volumes of plasma. Although centrifuges are ubiquitously used in clinical laboratories to separate plasma from whole blood, centrifugation is generally inappropriate for on-site testing. Suitable alternatives are not readily available to separate the relatively large volumes of plasma from milliliters of blood that may be needed to meet stringent limit-of-detection specifications for low abundance target molecules. We report on a simple to use, low-cost, pump-free, membrane-based, sedimentation-assisted plasma separator capable of separating a relatively large volume of plasma from undiluted whole blood within minutes. This plasma separator consists of an asymmetric, porous, polysulfone membrane housed in a disposable chamber. The separation process takes advantage of both gravitational sedimentation of blood cells and size exclusion-based filtration. The plasma separator demonstrated a “blood in-plasma out” capability, consistently extracting 275 ±33.5 μL of plasma from 1.8 mL of undiluted whole blood in less than 7 min. The device was used to separate plasma laden with HIV viruses from HIV virus-spiked whole blood with recovery efficiencies of 95.5% ± 3.5%, 88.0% ± 9.5%, and 81.5% ± 12.1% for viral loads of 35,000, 3,500 and 350 copies/mL, respectively. The separation process is self-terminating to prevent excessive hemolysis. The HIV-laden plasma was then injected into our custom-made microfluidic chip for nucleic acid Testing And Was Successfully Subjected To Reverse Transcriptase Loop mediated isothermal amplification (RT-LAMP), demonstrating that the plasma is sufficiently pure to support high efficiency nucleic acid amplification.

Limited Utility of Dried-Blood- and Plasma Spot-Based Screening for Antiretroviral Treatment Failure with Cobas Ampliprep/TaqMan HIV-1 Version 2.0

“…Liu et al reported on a simple-to-use and lowcost membrane-based sedimentation-assisted plasma separator capable of separating a relatively large volume of plasma from undiluted whole blood within minutes (26). A novel microfluidic blood filtration element (BFE) that extracts plasma from whole blood in less than 10 min was demonstrated by Homsy et al to be suitable for clinical application (27), and the use of red blood cell (RBC) agglutination for separating plasma from finger-prick volumes of whole blood directly in microfluid paper is also possible (28).…”

Self-driven filter-based blood plasma separator microfluidic chip for point-of-care testing

“…According to the results, the proposed design shows its potential as a clinical tool compared to previous works. Firstly, the initial volume of the required sample, 5µL, is considerably reduced compared to the former works [34,38]. Secondly, the volume of the extracted blood plasma, 0.1 µL, is enough to implement the TSH test and also is more than the obtained volume in the previous filter designs [33,35].…”

“…More recently, in 2013 a pump-free and membrane-based blood plasma separator is reported by Liu et al [38]. Gravitational sedimentation and filtration techniques were combined for nucleic acid amplification and HIV detection.…”

Imaging label-free biosensor with microfluidic system

“…Especially for blood filtration the small reagent volume needed in microfluidic systems is beneficial compared to conventional diagnostic devices in centralized facilities [2]. To separate plasma from whole blood different concepts were introduced such as special filter materials [3], designed filtration channels [2,4], or separation via a membrane [5]. Combining microfluidic concepts with a biosensor results in compact, decentralized, and fast operating devices [6,9].…”