• FAQ
    • Deposit your work
    • Login
    View Item 
    •   Rice Scholarship Home
    • Rice University Graduate Electronic Theses and Dissertations
    • Rice University Electronic Theses and Dissertations
    • View Item
    •   Rice Scholarship Home
    • Rice University Graduate Electronic Theses and Dissertations
    • Rice University Electronic Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Studying the Interactions of Biomacromolecular Assemblies with Surfaces Using the Microcantilever Sensor and Quartz Crystal Microbalance

    Thumbnail
    Name:
    LiuKai.pdf
    Size:
    4.269Mb
    Format:
    PDF
    View/Open
    Author
    Liu, Kai-Wei
    Date
    2011
    Advisor
    Biswal, Sibani Lisa
    Degree
    Doctor of Philosophy
    Abstract
    This thesis uses surface sensitive tools to characterize the effect of a solid surface on immobilized biomacromolecules. This includes understanding how the surface can change the affinity of these macromolecules to small molecules compared to bulk studies. Two classes of immobilized biomacromolecules, the supported lipid bilayer (SLB) and the Lac repressor protein (LacI), are characterized using microcantilever sensors and quartz crystal microbalance with dissipation (QCM-D). The first part of this thesis reports the use of microcantilever beams, an ultrasensitive sensor for measuring the surface free energy changes on a substrate induced by molecular adsorptions, to probe the interaction between a solid surface and a phospholipid bilayer. This sensing method integrates two well-developed techniques: solid-supported lipid bilayers (SLBs) and the microcantilever (MC) sensors. Studying the adsorption free energy of lipid bilayers on a solid surface allows better characterizing of the formation and stability of SLBs. Microcantilever converts the Gibbs free energy change taking place on its surface into a mechanical deformation. As molecules physisorb or chemisorb onto the surface of the microcantilevers, the microcantilevers bend, either due to induced compressive or tensile stresses, which result from the surface free energy change. By monitoring the deflection values of the microcantilevers, the real-time surface free energy change during the SLB formation can be detected. This thesis has led to the development of a novel biosensor--lipid membrane coated microcantilevers--to detect the adsorption, insertion, aggregation and solubilizing effect of membrane-active substances, such as surfactants and peptides, on the phospholipid membranes. To better characterize the surface free energy, SLBs doped with charged lipids or cholesterol are shown to alter the surface free energy. We can predict this change in surface free energy using a thermodynamic model. Application of this membrane-coated cantilever is put into use for detecting how amphiphilic molecules interact with SLBs, as well as for probing the abrupt conformational change of SLBs during a temperature induced phase-transition. This study systematically demonstrates various usage aspects of microcantilever to characterize the SLBs, and how this technique may advance the biophysical knowledge of the lipid membrane, one of the essential building blocks of life. The second part of this thesis reports the use of both microcantilever sensors and QCM-D to measure the adsorption free energy and mass of a model protein, the Lac repressor (LacI), and compare how a modified T334C mutant that includes a cysteine group to orient the protein on the gold surface through a covalent sulfur bonds retains its binding capabilities over that of wild type LacI. The main challenge of this work is to unravel how the adsorption of biomacromolecules at the solid/liquid interface leads to surface free energy changes and ultimately changes the stress of the underlying solid surface (the cantilever). The uses of microcantilever sensors and QCM to probe the interactions that take place on SLBs and surface-bound proteins have the advantage of being a sensitive, real-time, and label-free technique.
    Keyword
    Applied sciences; Microcantilever sensors; Supported lipid bilayers; Quartz crystal microbalances; Chemical engineering
    Metadata
    Show full item record
    Collections
    • Rice University Electronic Theses and Dissertations [10740]

    Home | FAQ | Contact Us
    Managed by the Digital Scholarship Services at Fondren Library, Rice University
    Physical Address: 6100 Main Street, Houston, Texas 77005
    Mailing Address: MS-44, P.O.BOX 1892, Houston, Texas 77251-1892
     

     

    Browse

    Entire ArchiveCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsTypeThis CollectionBy Issue DateAuthorsTitlesSubjectsType

    My Account

    Login

    Statistics

    View Usage Statistics

    Home | FAQ | Contact Us
    Managed by the Digital Scholarship Services at Fondren Library, Rice University
    Physical Address: 6100 Main Street, Houston, Texas 77005
    Mailing Address: MS-44, P.O.BOX 1892, Houston, Texas 77251-1892