subject:(Biological separations)

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1. McCallum, Christopher Craig. Modeling Complex Electrokinetic Nanofluidic Systems.

Degree: 2017, University of California – eScholarship, University of California

URL: http://www.escholarship.org/uc/item/3859826d

The electrical double layer (EDL) nano-structure at the interface between electrolytes and charged surfaces dominates the performance of a myriad of electrokinetic and electrochemical processes. A complete understanding of the EDL nano-structure allows for a predictive tool for various systems such as supercapacitors, desalination, and nano-particle manipulation. My work involves developing theoretical models to elucidate the nano-structure of the EDL and the consequent effects on fluid flow and species transport in such systems. These include models explaining dispersion of ions in channels with thick EDLs, surface-charge-based ion conductivity changes, nanofluidic-based DNA hybridization, nanofluidic isotachophoresis, charge inversion due to large ions, and nanofluidic systems with heterogeneous surface charges. Collectively, these studies have enriched our understanding of complex electrokinetic nanochannel transport.First, I describe a model for the EDL in nanofluidic channels, showing experimentally validated theoretical regimes where dispersion and/or significant EDL size might affect experimental results, as well as methods to account for these effects. Understanding these effects is essential to accurately interpret experiments as well as design of future experiments and subsequent applications. This model can further explain other micro- and nanoscale electrokinetic transport physics. For example, 1) this theory can explain nanochannel conductivity changes due to changes in surface charge, 2) accounting for reaction terms, it can accurately model non-equilibrium DNA hybridization as well as the effect of nano-confinement on such hybridization in electrokinetic capillary electrophoresis-based systems, 3) it can predict an isotachophoretic-like standing front in nanochannels with surface-charge-inverting complex ionic species that induce fluid flow reversal, and 4) it can describe behavior with heterogeneous surface charge. To explain the behavior of nanofluidic systems with heterogeneous surface charge and complex ionic species, I refined the model by accounting for hard-sphere ion size and more complex near-field screening effects using classical Density Functional Theory. I conducted a theoretical study to explore heterogeneous surface charge in nanochannels with embedded, addressable electrodes that allow us to fully probe EDL structure. I developed a more complete EDL model and performed a systematic theoretical study of EDL nano-structure by varying ion diameter, valence, and concentration, as well as surface charge in order to elucidate EDL nano-structure, fluid flow, and species transport in nanochannels. Thus far we have preliminary model validation using custom-fabricated nanochannels with complex ions, and further experiments will both interpret nanochannel physics through theory as well as improve the model via experimental feedback, overall enabling a more complete predictive theory for future experimental and application design.

Subjects/Keywords: Mechanical engineering; biological separations; density functional theory; electrokinetics; nanofluidics

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APA (6^th Edition):

McCallum, C. C. (2017). Modeling Complex Electrokinetic Nanofluidic Systems. (Thesis). University of California – eScholarship, University of California. Retrieved from http://www.escholarship.org/uc/item/3859826d

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

McCallum, Christopher Craig. “Modeling Complex Electrokinetic Nanofluidic Systems.” 2017. Thesis, University of California – eScholarship, University of California. Accessed April 16, 2021. http://www.escholarship.org/uc/item/3859826d.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

McCallum, Christopher Craig. “Modeling Complex Electrokinetic Nanofluidic Systems.” 2017. Web. 16 Apr 2021.

Vancouver:

McCallum CC. Modeling Complex Electrokinetic Nanofluidic Systems. [Internet] [Thesis]. University of California – eScholarship, University of California; 2017. [cited 2021 Apr 16]. Available from: http://www.escholarship.org/uc/item/3859826d.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

McCallum CC. Modeling Complex Electrokinetic Nanofluidic Systems. [Thesis]. University of California – eScholarship, University of California; 2017. Available from: http://www.escholarship.org/uc/item/3859826d

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

2. Kazemi, Amir Sadegh. Development of High-throughput Membrane Filtration Techniques for Biological and Environmental Applications.

Degree: PhD, 2018, McMaster University

URL: http://hdl.handle.net/11375/23404

Membrane filtration processes are widely utilized across different industrial sectors for biological and environmental separations. Examples of the former are sterile filtration and protein fractionation via microfiltration (MF) and ultrafiltration (UF) while drinking water treatment, tertiary treatment of wastewater, water reuse and desalination via MF, UF, nanofiltration (NF) and reverse-osmosis (RO) are examples of the latter. A common misconception is that the performance of membrane separation is solely dependent on the membrane pore size, whereas a multitude of parameters including solution conditions, solute concentration, presence of specific ions, hydrodynamic conditions, membrane structure and surface properties can significantly influence the separation performance and the membrane’s fouling propensity. The conventional approach for studying filtration performance is to use a single lab- or pilot-scale module and perform numerous experiments in a sequential manner which is both time-consuming and requires large amounts of material. Alternatively, high-throughput (HT) techniques, defined as the miniaturized version of conventional unit operations which allow for multiple experiments to be run in parallel and require a small amount of sample, can be employed. There is a growing interest in the use of HT techniques to speed up the testing and optimization of membrane-based separations. In this work, different HT screening approaches are developed and utilized for the evaluation and optimization of filtration performance using flat-sheet and hollow-fiber (HF) membranes used in biological and environmental separations. The effects of various process factors were evaluated on the separation of different biomolecules by combining a HT filtration method using flat-sheet UF membranes and design-of-experiments methods. Additionally, a novel HT platform was introduced for multi-modal (constant transmembrane pressure vs. constant flux) testing of flat-sheet membranes used in bio-separations. Furthermore, the first-ever HT modules for parallel testing of HF membranes were developed for rapid fouling tests as well as extended filtration evaluation experiments. The usefulness of the modules was demonstrated by evaluating the filtration performance of different foulants under various operating conditions as well as running surface modification experiments. The techniques described herein can be employed for rapid determination of the optimal combination of conditions that result in the best filtration performance for different membrane separation applications and thus eliminate the need to perform numerous conventional lab-scale tests. Overall, more than 250 filtration tests and 350 hydraulic permeability measurements were performed and analyzed using the HT platforms developed in this thesis.

Thesis

Doctor of Philosophy (PhD)

Membrane filtration is widely used as a key separation process in different industries. For example, microfiltration (MF) and ultrafiltration (UF) are used for sterilization and…

Advisors/Committee Members: Latulippe, David, Chemical Engineering.

Subjects/Keywords: Membrane filtration; Ultrafiltration; Downstream bio-processing; High-throughput (HT) testing; Wastewater treatment; Hollow-fiber membranes; Humic acids; High-throughput filtration; Design-of-experiments (DOE); Process optimization; Microscale filtration; Microfluidic flow control system; Stirred well filtration; SWF; High-throughput hollow-fiber module; HT-HF; Constant TMP; Constant flux; Multi-modal filtration; Bioseparation; MMFC; Microscale parallel-structured, cross-flow filtration; MS-PS-CFF; PEG; Dextran; FITC-Dextran; BSA; DNA; IgG; α-lactalbumin; Biomolecule separation; Module hydrodynamics; Concentration polarization; Membrane fouling; Micromixing; Omega™ membrane; Microscale processing; Fouling test; PVDF membrane; Surface modification; Polydopamine; Membrane cleaning; Membrane backwashing; Sodium alginate; Polyethersulfone; PES; Hydraulic permeability; Membrane permeability; ZeeWeed® membrane; Filtration ionic strength; Filtration pH; Solution conditions; Water treatment; Environmental separations; Biological separations

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APA (6^th Edition):

Kazemi, A. S. (2018). Development of High-throughput Membrane Filtration Techniques for Biological and Environmental Applications. (Doctoral Dissertation). McMaster University. Retrieved from http://hdl.handle.net/11375/23404

Chicago Manual of Style (16^th Edition):

Kazemi, Amir Sadegh. “Development of High-throughput Membrane Filtration Techniques for Biological and Environmental Applications.” 2018. Doctoral Dissertation, McMaster University. Accessed April 16, 2021. http://hdl.handle.net/11375/23404.

MLA Handbook (7^th Edition):

Kazemi, Amir Sadegh. “Development of High-throughput Membrane Filtration Techniques for Biological and Environmental Applications.” 2018. Web. 16 Apr 2021.

Vancouver:

Kazemi AS. Development of High-throughput Membrane Filtration Techniques for Biological and Environmental Applications. [Internet] [Doctoral dissertation]. McMaster University; 2018. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/11375/23404.

Council of Science Editors:

Kazemi AS. Development of High-throughput Membrane Filtration Techniques for Biological and Environmental Applications. [Doctoral Dissertation]. McMaster University; 2018. Available from: http://hdl.handle.net/11375/23404

University of Canterbury

3. Van Alstine, J.M. PEG-proteins: Reaction engineering and separation issues.

Degree: Chemical and Process Engineering., 2005, University of Canterbury

URL: http://hdl.handle.net/10092/353

Poly(ethylene glycol)-conjugated (or PEGylated) proteins are an increasingly important class of therapeutic proteins that offer improved in vivo circulation half lives over their corresponding native forms. Their production involves covalent attachment of one or more poly(ethylene glycol) molecules to a native protein, followed by purification. Because of the extremely high costs involved in producing native therapeutic proteins it is important that subsequent PEGylation processes are as efficient as possible. In this paper, reaction engineering and purification issues for PEGylated proteins are reviewed. Paramount considerations for PEGylation reactions are specificity with respect to the conjugation site and overall yield. Batch PEGylation reaction methods are discussed, along with innovative methods using packed bed or “on-column” approaches to improve specificity and yield. Purification methods are currently dominated by ion exchange and size exclusion chromatography. Other methods in common use for protein separations, including hydrophobic interaction chromatography, affinity chromatography and membrane separations, are rarely used in PEGylated protein purification schemes. A better understanding of the effects of PEGylation on the physicochemical properties of proteins (isoelectric point, surface charge density and distribution, molecular size and relative hydrophobicity) and interactions between PEGylated proteins and surfaces is needed for the future development of optimal purification processes and media.

Subjects/Keywords: PEGylation; proteins; biochemical engineering; separations; reaction engineering; chromatography; Fields of Research::290000 Engineering and Technology::290600 Chemical Engineering::290699 Chemical engineering not elsewhere classified; Fields of Research::270000 Biological Sciences::270100 Biochemistry and Cell Biology; Fields of Research::250000 Chemical Sciences::250300 Organic Chemistry

Record Details Similar Records Cite « Share

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6^th Edition):

Van Alstine, J. M. (2005). PEG-proteins: Reaction engineering and separation issues. (Thesis). University of Canterbury. Retrieved from http://hdl.handle.net/10092/353

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16^th Edition):

Van Alstine, J M. “PEG-proteins: Reaction engineering and separation issues.” 2005. Thesis, University of Canterbury. Accessed April 16, 2021. http://hdl.handle.net/10092/353.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7^th Edition):

Van Alstine, J M. “PEG-proteins: Reaction engineering and separation issues.” 2005. Web. 16 Apr 2021.

Vancouver:

Van Alstine JM. PEG-proteins: Reaction engineering and separation issues. [Internet] [Thesis]. University of Canterbury; 2005. [cited 2021 Apr 16]. Available from: http://hdl.handle.net/10092/353.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Van Alstine JM. PEG-proteins: Reaction engineering and separation issues. [Thesis]. University of Canterbury; 2005. Available from: http://hdl.handle.net/10092/353

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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