Quantitative analysis of membrane fouling by protein mixtures using MALDI‐MS

Abstract

Binary aqueous solutions of bovine serum albumin (BSA) and beta-lactoglobulin (bLG) were subject to flux-stepping and constant flux ultrafiltration to identify the apparent critical flux and to study the mechanisms and factors affecting fouling when the membrane is permeable to one protein component. Membranes from these filtration experiments were analyzed using matrix-assisted laser desorption ionization mass spectrometry (MALDI-MS) to locate and quantify levels of fouling below and above the apparent critical flux. Hydrophilic (PLTK) regenerated cellulose and hydrophobic (PBTK) polysulfone asymmetric membranes were used, both of 30 kDa nominal molecular weight cut-off. For the hydrophilic PLTK membrane, protein deposition was shown to depend on electrostatic forces, exhibiting little or no fouling when the proteins had the same charge sign as that of the membrane. This was found to apply for both dilute equal mass-per-unit-volume and equimolar binary mixtures. For the PBTK membrane, hydrophobic protein-membrane attractive forces were sufficiently strong to cause deposition of bLG even in the presence of repulsive electrostatic forces. For the PBTK membrane deposition exceeded monolayer coverage below and above apparent critical flux conditions but for the PLTK membrane this generally occurred when the apparent critical flux was exceeded. MALDI-MS was shown to be a facile direct analytical technique for individually quantifying adsorbed proteins on membrane surfaces at levels as low as 50 fmol/mm(2). The high levels of compound specificity inherent to mass spectrometry make this approach especially suited to the quantification of individual components in mixed deposits. In this study, MALDI-MS was found to be successful in identifying and quantifying the protein species responsible for fouling.

Protein (BSA) fouling of reverse osmosis membranes: Implications for wastewater reclamation

“…There have been numerous studies on protein fouling of other types of membranes [8][9][10][11][12], but limited studies on fouling of RO membranes. The fouling mechanisms of MF membranes by BSA have been attributed to membrane pore blocking and/or pore constriction during initial fouling, followed by cake formation on the membrane surface during long-term fouling [12].…”

Exploration of ionic modification in dual‐layer hollow fiber membranes for long‐term high‐performance protein separation

“…9,12 Regrettably, the high performance of UF membranes is not easily maintained over time as significant fouling occurs after the process commences. [14][15][16] Although membrane fouling is a very complicated process, many investigations have shown that an increment in membrane hydrophilicity will inevitably inhibit protein adsorption and deposition, thereby significantly reducing membrane fouling. [17][18][19] Therefore, the ionic modification was applied with the aid of dual-layer hollow fiber technology in this work to tune the pore size and pore size distribution, introduce the electrostatic interaction, and reduce membrane fouling for longterm high-performance protein separation.…”

Enhanced Detection of Low-Abundance Human Plasma Proteins by Integrating Polyethylene Glycol Fractionation and Immunoaffinity Depletion

“…Centrifugal ultrafiltration is used to for enrich low-molecular-weight proteins, which are considered as an important source of biomarkers [21, 22]. In contrast, protein precipitation is often more preferable other than ultrafiltration, because the membranes are not so robust enough for high protein concentrations and suffering from fouling that used for ultrafiltration [23, 24]. Recent reviews have systematically described the increasing number of initial fractionation approaches used for plasma proteomic analysis [25].…”