Encapsulation of Synthetic Materials in Biological Self-Assembled Systems

2010 2010

Other formats: Order a copy

Abstract (summary)

Protein cages are unique building blocks in biological research due to their versatility and wide ranging potential applications in drug delivery and biological imaging and sensing. This dissertation addresses the use of two different protein cages, vaults and viral capsids, to package synthetic and biological materials, providing the groundwork for using these biocages in encapsulation and delivery applications.

The first part of this dissertation explores the use vaults with a goal of packaging materials in the particle interior. Three fundamental issues are addressed: 1) can a foreign material be packaged? 2) can release be controlled? 3) how do biological materials access the vault interior? For question 1, a fluorescent polyanionic semiconducting polymer [poly(2-methoxy-5-propyloxy sulfontate phenylene vinylene), MPS-PPV] was encapsulated inside vaults to form optically active protein cages. Polymer incorporation into vaults was confirmed by fluorescence spectroscopy and small-angle X-ray scattering. For question 2, a bifunctional amine-reactive reagent can be used for the reversible cross-linking of vaults to trap the polymer inside. For question 3, we examine vault fluctuations in solution. Three independent sets of experiments indicate that vaults can separate into open halves in solution and that these halves can sometimes exchange. Finally, we explored the possibility of engineering vaults with designed functions. Metal-binding proteins were fused to a vault binding domain. These vaults bind lead and copper ions and could be used for therapeutics and medical imaging reagents.

The second part of this dissertation discusses the use of a more rigid protein cage from Cowpea Chlorotic Mottle Virus to encapsulate luminescent species. The flexible polymer polystyrene-sulfonate conjugated with rhodamine-B (PSS-Rh), and the more rigid MPS-PPV are used to obtain optically active virus-like particles with different structures. The PSS-Rh polymer can be packaged into spherical structures and retain its fluorescent. However, its flexible conformation cannot control the shape of the biocage. MPS-PPV, however, whose conformation is sensitive to its local environment, can control the architecture of viral capsids. Results from fluorescence spectroscopy, TEM, and sucrose gradient separation indicate that MPS-PPV can be encapsulated into spherical particles or rod-like structures depending on the ionic strength and the MPS-PPV conformation during assembly.

Indexing (details)

Physical chemistry;
0494: Physical chemistry
0786: Biophysics
Identifier / keyword
Pure sciences; Biological sciences; Protein cages; Rhodamine; Self-assembly; Viral capsids
Encapsulation of Synthetic Materials in Biological Self-Assembled Systems
Ng, Benny Chun Hei
Number of pages
Publication year
Degree date
School code
DAI-B 72/06, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
Tolbert, Sarah H.
University of California, Los Angeles
University location
United States -- California
Source type
Dissertations & Theses
Document type
Dissertation/thesis number
ProQuest document ID
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
Access the complete full text

You can get the full text of this document if it is part of your institution's ProQuest subscription.

Try one of the following:

  • Connect to ProQuest through your library network and search for the document from there.
  • Request the document from your library.
  • Go to the ProQuest login page and enter a ProQuest or My Research username / password.