FIB-SEM tomography reveals the nanoscale 3D morphology of virus removal filters

Brickey, Kaitlyn P.; Zydney, Andrew L.; Gomez, Enrique D.

doi:10.1016/j.memsci.2021.119766

Cited by 20 publications

(7 citation statements)

References 32 publications

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“…It was noted that two‐dimensional (2D) image analysis for membrane morphology had some limitations, such as limited estimation of the circular shape of pores, discrepancy of cross‐sectional pore structure, and limited analysis of pore interconnectivity. Although 3D image analysis, for example, using focused ion beam‐SEM tomography, provides better interpretation (Brickey et al, 2021), 2D SEM images can be used to simply distinguish structural differences among virus‐retentive membranes. The difference in membrane structure and nominal pore size suggested that different fouling propensities and virus removal performances are expected under the same experimental conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Interestingly, the best‐fitted fouling model for Viresolve® Pro was changed to the standard blocking at higher protein concentration showing the lowest RMSE value (Table S4). Viresolve® Pro had shallow PSGs from membrane exit with high interconnectivity (Brickey et al, 2021; Fallahianbijan et al, 2019) where relatively lower contents of large oligomers dominantly blocked the pores (i.e., complete blocking) at 1 g/L of BSA solution while relatively smaller BSA with large contents (>75%) at higher protein concentration condition would mainly clogged the pores, resulted in the changed the model to standard blocking. It is noted that Virosart® CPV still matched with the complete blocking model at 10 g/L of BSA solution (Figure S6).…”

Section: Resultsmentioning

confidence: 99%

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Effect of protein fouling on filtrate flux and virus breakthrough behaviors during virus filtration process

Suh

Jin

Park

et al. 2023

Biotech & Bioengineering

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Virus filtration process is used to ensure viral safety in the biopharmaceutical downstream processes with high virus removal capacity (i.e., >4 log10). However, it is still constrained by protein fouling, which results in reduced filtration capacity and possible virus breakthrough. This study investigated the effects of protein fouling on filtrate flux and virus breakthrough using commercial membranes that had different symmetricity, nominal pore size, and pore size gradients. Flux decay tendency due to protein fouling was influenced by hydrodynamic drag force and protein concentration. As the results of prediction with the classical fouling model, standard blocking was suitable for most virus filters. Undesired virus breakthrough was observed in the membranes having relatively a large pore diameter of the retentive region. The study found that elevated levels of protein solution reduced virus removal performance. However, the impact of prefouled membranes was minimal. These findings shed light on the factors that influence protein fouling during the virus filtration process of biopharmaceutical production.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Effect of protein fouling on filtrate flux and virus breakthrough behaviors during virus filtration process

Suh

Jin

Park

et al. 2023

Biotech & Bioengineering

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“…28 Physical entrapment of viruses in the inner pore voids of the membrane is similar to the established removal mechanisms of particle entrapment inside depth filters. 29 Recent research has demonstrated that virus retention by common MF and UF membranes could be increased by modifying the surface and pore structure, which primarily enhances adsorption interactions. For example, surface functionalization of a polyethersulfone (PES) membrane with polyethyleneimine (PEI) improved its removal of MS2 bacteriophages by about 3 LRV.…”

Section: Introductionmentioning

confidence: 99%

“…The virus adsorption capacity depends on the membrane material, the type of virus (i.e., the capsid size and properties), , and solution properties . Physical entrapment of viruses in the inner pore voids of the membrane is similar to the established removal mechanisms of particle entrapment inside depth filters …”

Section: Introductionmentioning

confidence: 99%

Microporous Polyethersulfone Membranes Grafted with Zwitterionic Polymer Brushes Showing Microfiltration Permeance and Ultrafiltration Bacteriophage Removal

Qin

Ziemann

Bar‐Zeev

et al. 2023

ACS Appl. Mater. Interfaces

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Virus removal from water using microfiltration (MF) membranes is of great interest but remains challenging owing to the membranes' mean pore sizes typically being significantly larger than most viruses. We present microporous membranes grafted with polyzwitterionic brushes (N-dimethylammonium betaine) that combine bacteriophage removal in the range of ultrafiltration (UF) membranes with the permeance of MF membranes. Brush structures were grafted in two steps: free-radical polymerization followed by atom transfer radical polymerization (ATRP). Attenuated total reflection Fourier transform infrared (ATR−FTIR) and X-ray photoelectron (XPS) verified that grafting occurred at both sides of the membranes and that the grafting increased with increasing the zwitterion monomer concentration. The log reduction values (LRVs) of the pristine membrane increased from less than 0.5 LRV for T4 (∼100 nm) and NT1 (∼50 nm) bacteriophages to up to 4.5 LRV for the T4 and 3.1 LRV for the NT1 for the brush-grafted membranes with a permeance of about 1000 LMH/bar. The high permeance was attributed to a high-water fraction in the ultra-hydrophilic brush structure. The high measured LRVs of the brush-grafted membranes were attributed to enhanced bacteriophages exclusion from the membrane surface and entrapment of the ones that penetrated the pores due to the membranes' smaller mean pore-size and crosssection porosity than those of the pristine membrane, as seen by scanning electron microscopy (SEM) and measured using liquid− liquid porometry. Micro X-ray fluorescence (μ-XRF) spectrometry and nanoscale secondary ion mass spectrometry showed that 100 nm Si-coated gold nanospheres accumulated on the surface of the pristine membrane but not on the brush-coated membrane and that the nanospheres that penetrated the membranes were entrapped in the brush-grafted membrane but passed the pristine one. These results corroborate the LRVs obtained during filtration experiments and support the inference that the increased removal was due to a combined exclusion mechanism and entrapment. Overall, these microporous brush-grafted membranes show potential for use in advanced water treatment.

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“…Reingruber et al 39 an ultramicrotome mounted in the specimen chamber of an environmental scanning electron microscope (SEM) to visualize and quantitatively characterize the 3D microporous structure of commercially available polyethersulfone microfiltration membranes with nominal pore sizes of 0.45 and 0.60 μm. Brickey et al 40 analyzed the 3D morphology of virus removal filters and estimated the virus retentive pore diameter using a focused ion beam SEM (FIB-SEM). Qin et al 41 demonstrated the superiority of FIB-SEM over freeze-fracture in imaging polymeric and inorganic membranes.…”

Section: Introductionmentioning

confidence: 99%

High-Resolution Numerical Simulation of Microfiltration of Oil-in-Water Emulsion Permeating through a Realistic Membrane Microporous Structure Generated by Focused Ion Beam Scanning Electron Microscopy Images

et al. 2022

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Owing to the limitations of visualization techniques in experimental studies and low-resolution numerical models based on computational fluid dynamics (CFD), the detailed behavior of oil droplets during microfiltration is not well understood. Hence, a high-resolution CFD model based on an in-house direct numerical simulation (DNS) code was constructed in this study to analyze the detailed dynamics of an oil-in-water (O/W) emulsion using a microfiltration membrane. The realistic microporous structure of commercial ceramic microfiltration membranes (mullite and αalumina membranes) was obtained using an image processing technique based on focused ion beam scanning electron microscopy (FIB-SEM). Numerical simulations of microfiltration of O/W emulsions on the membrane microstructure obtained by FIB-SEM were performed, and the effects of different parameters, including contact angle, transmembrane pressure, and membrane microporous structure, on filtration performance were studied. Droplet deformation had a strong impact on filtration behavior because coalesced droplets with diameters larger than the pore diameter permeated the membrane pores. The permeability, oil holdup fraction inside the pores, and rejection were considerably influenced by the contact angle, while the transmembrane pressure had a little impact on the permeability and oil hold-up fraction. The membrane structure, especially the pore size distribution, also had a significant effect on the microfiltration behavior and performance.

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FIB-SEM tomography reveals the nanoscale 3D morphology of virus removal filters

Cited by 20 publications

References 32 publications

Effect of protein fouling on filtrate flux and virus breakthrough behaviors during virus filtration process

Effect of protein fouling on filtrate flux and virus breakthrough behaviors during virus filtration process

Microporous Polyethersulfone Membranes Grafted with Zwitterionic Polymer Brushes Showing Microfiltration Permeance and Ultrafiltration Bacteriophage Removal

High-Resolution Numerical Simulation of Microfiltration of Oil-in-Water Emulsion Permeating through a Realistic Membrane Microporous Structure Generated by Focused Ion Beam Scanning Electron Microscopy Images

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