Biomimetic membranes as new materials for applications in envrionmental engineering and biology

Kumar, Manish

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https://hdl.handle.net/2142/16976 Copy

Description

Title

Biomimetic membranes as new materials for applications in envrionmental engineering and biology

Author(s)

Kumar, Manish

Issue Date

2010-08-31T20:02:50Z

Director of Research (if dissertation) or Advisor (if thesis)

Clark, Mark M.

Doctoral Committee Chair(s)

Zilles, Julie L.

Committee Member(s)

• Clark, Mark M.
• Snoeyink, Vernon L.
• Meier, Wolfgang P.

Department of Study

Civil & Environmental Eng

Discipline

Environ Engr in Civil Engr

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

• Biomimetic Membranes
• Aquaporins
• Block copolymers
• Desalination

Abstract

Biological water channel proteins, called aquaporins, provide selective and rapid transport of water across cell membranes. They utilize an elegant mechanism distinct from and more efficient than that used in commercial solute separation polymeric membranes such as Reverse Osmosis (RO) membranes. In this work, the bacterial Aquaporin (AqpZ) was functionally incorporated into synthetic biomimetic polymer vesicles. Using stopped flow light scattering, the permeability of such systems was determined to be up to two orders of magnitude higher than current RO membranes, revealing the potential of this approach. A templating procedure was then used to make flat membrane films with a high density of AqpZ. The sizes of these films are small (~500 nm) and more research needs to be performed to scale up this process. However, this method led to creation of flat 2D or thin 3D crystals of AqpZ in a polymer matrix as confirmed by electron diffraction. This indicates that the packing efficiency of these polymer-based systems is extremely high. Additionally, such crystals have the potential to allow for structural reconstruction of the incorporated aquaporins. This procedure can thus provide fundamental knowledge regarding the conformation of membrane proteins in block copolymers and help in design of functional protein-polymer hybrid materials. This work also led to the serendipitous discovery of AqpZ gating (reversible closure) at low pH values when incorporated into triblock copolymer vesicles. This gating is also present in bacteria and has relevance for bacterial survival under acid and osmotic shock. An overall scheme of osmoregulation and acidic shock survival utilizing coordinated activation and gating of membrane proteins is proposed. Several research ideas resulted from this work and are currently being pursued. This includes determination of insertion efficiency of membrane proteins in block copolymers, the use of block copolymer membranes for studying gas transport in membrane proteins, block copolymer vesicles with encapsulated perchlorate degrading enzymes for water treatment, and carbon capture using active CO2 transporters inserted into block copolymer membranes. Overall, this work has demonstrated the promise of using hybrid protein-polymer systems for environmental engineering applications. In particular its applicability to synthetic desalination membranes is most promising and relevant. The basic approach used here may be applied to any separation for which a specific transport protein is available or could be engineered. My work has also contributed to understanding the properties of aquaporins, in particular AqpZ and its possible role in microbial physiology. Finally, recent successes in immobilizing protein molecules and in synthesizing 2D crystals of membrane proteins may provide an excellent way to answer fundamental questions regarding the structure and function of these membrane proteins in block copolymers. In broad terms, this work has shown that biology provides excellent paradigms for engineering materials and processes that are efficient and sustainable and that this “reverse engineering” approach can enrich our understanding of underlying biological phenomena

Graduation Semester

2010-08

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Copyright and License Information

Copyright 2010 Manish Kumar

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