Digital Microfluidic Platform for Human Plasma Protein Depletion

Abstract

Many important biomarkers for disease diagnosis are present at low concentrations in human serum. These biomarkers are masked in proteomic analysis by highly abundant proteins such as human serum albumin (HSA) and immunoglobulins (IgGs) which account for up to 80% of the total protein content of serum. Traditional depletion methods using macro-scale LC-columns for highly abundant proteins involve slow separations which impart considerable dilution to the samples. Furthermore, most techniques lack the ability to process multiple samples simultaneously. We present a method of protein depletion using superparamagnetic beads coated in anti-HSA, Protein A, and Protein G, manipulated by digital microfluidics (DMF). The depletion process was capable of up to 95% protein depletion efficiency for IgG and HSA in 10 min for four samples simultaneously, which resulted in an approximately 4-fold increase in signal-to-noise ratio in MALDI-MS analysis for a low abundance protein, hemopexin. This rapid and automated method has the potential to greatly improve the process of biomarker identification.

Building bio-assays with magnetic particles on a digital microfluidic platform

“…blood), which are rich in highly abundant proteins (HAPs), such as immunoglobulins. Recently, Mei et al [74] reported a method of protein depletion integrated in an EWOD-DMF set up. The method relies on magnetic particles coated with specific antibodies or proteins towards HAPs which were brought into contact with the sample solution.…”

“…The group of Wheeler also integrated all necessary instrumentation in a benchtop device (18 Â 23 Â 30 cm), [57,74] (Fig. 11C).…”

Flow Lectin Affinity Chromatography−A Model with Sambucus nigra Agglutinin

“…Although there is a rising tendency to automate analytical procedures used in proteomic research through flow methodologies [10,[16][17][18][19], usually LAC is carried out in batch conditions (using the commercial columns and kits) [20] or using sophisticated chromatographic equipments [21][22][23], which implies a long procedure time and high consumption of consumables, or capability of laboratories to purchase expensive apparatus. If the LAC procedure is performed under flow conditions, this allows automation of the process, especially important when several samples need to be run, and reduces solution and sample manipulation steps and resultant losses, ex-vivo proteolysis or chemical modifications during procedures [10].…”

Magnetic droplet actuation on natural (Colocasia leaf) and fluorinated silica nanoparticle superhydrophobic surfaces

“…Extensive and comprehensive analysis of ferrofluidic manipulation on DMF devices has been previously reported therefore here we concentrate on aqueous droplets containing paramagnetic particles only [24,30,31]. Commercial "magnetic particles" for this purpose are based on (super)paramagnetic particles, where an iron oxide core is surrounded by a layer of silica, which can be functionalized as desired for a given application [32][33][34][35]. Many devices using magnetic actuation have been reported, and complex droplet movement has been demonstrated in three dimensions, including actuation of an inverted droplet [20].…”