Merlin Bruening
Professor Office: 311 Chemistry
Phone: 517-355-9715 237 /
Websites: Research Group - Area
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Ultrathin Films for Separation and Analysis
(Research Description PDF - 1425 kb)Our current research focus is the development of thin films for separations and analysis. One area of this work involves alternating adsorption of polycations and polyanions to form ultrathin separation membranes on highly porous supports. Judicious selection of the constituent polyelectrolytes in these films affords membranes that are selectively permeable to ions and neutral molecules such as sugars. Target applications range from water softening and salt purification to separation of proteins and peptides.
In a second area, we are developing methods to synthesize "giant" polymer brushes from surfaces. These micron-long, tethered polymers can serves as substrates for immobilization of biomolecules such as DNA and antibodies. Control over chain density regulates brush swelling and should allow enhancements in the accessibility of immobilized molecules for subsequent binding assays. When arrays of affinity molecules are bound to the surface, detection of binding to these probes should permit simultaneous analysis of a plethora of proteins or DNA fragments.
We also employ immobilized affinity probes for selective binding of biomolecules to enhance analysis by matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. Currently, we are utilizing Fe(III) complexes to capture phosphorylated peptides directly on the MALDI probe. Determination of phosphorylation sites in proteins is important for understanding processes such as cell regulation and signaling.
The final focus of our research is synthesis of films containing catalytic nanoparticles. Using alternating adsorption of polymeric metal-ion complexes and a polyanion followed by reduction of the metal ion, we can synthesize catalytic nanoparticles in ultrathin films. We are currently investigating the use of these films as antibacterial coatings and selective catalysts in reactions such as hydrogenation of organic compounds.
All of these projects require thorough surface characterization. To investigate ultrathin films and their properties, we employ atomic force microscopy, field-emission scanning electron microscopy, ellipsometry, electrochemical techniques, grazing angle reflectance infrared spectroscopy, X-ray photoelectron spectroscopy, contact-angle measurements, fluorescence spectroscopy, and permeation measurements
Selected Publications
High-capacity Binding of Proteins by Derivatized Poly(Acrylic Acid) Brushes, J. Dai, Z. Bao, L. Sun, G.L. Baker, and M.L. Bruening, Langmuir 2006, 22, 4274-4281.Detection of Phosphopeptides Using Fe(III)-Nitrilotriacetate Complexes Immobilized on a MALDI Plate, J.D. Dunn, J.T. Watson, and M.L. Bruening, Anal. Chem. 2006, 78, 1574-1580.
Use of Porous Membranes Modified with Polyelectrolyte Multilayers as Substrates for Highly Sensitive Protein Arrays with Low Non-specific Adsorption, J. Dai, G.L. Baker, and M.L. Bruening, Anal. Chem. 2006, 78, 135-140.
Catalytic Membranes Prepared Using Layer-by-Layer Adsorption of Polyelectrolytes and Metal Nanoparticles in Porous Supports, D.M. Dotzauer, J. Dai, L. Sun, and M.L. Bruening, Nano Letters 2006, 6, 2268-2272.
Rapid Growth of Polymer Brushes from Immobilized Initiators, Z. Bao, M.L. Bruening, and G.L. Baker, J. Am. Chem. Soc. 2006, 128, 9056-9060.
Separation of Fluoride from Other Monovalent Anions Using Multilayer Polyelectrolyte Nanofiltration Membranes, S.U. Hong, R. Malaisamy, and M.L. Bruening, Langmuir 2007, 23, 1716-1722.
