Paul E. Laibinis

Research Interests:

• Surface engineering
• Interfacial phenomena
• Self-assembly
• Chemical sensor design; biosurfaces; nanotechnology

Education:

• S.B. (1985) Massachusetts Institute of Technology
• Ph.D. (1991) Harvard

Solid-solid and solid-liquid interactions are ubiquitous in chemical processes and materials applications. Microscopic details of these interactions play an integral part in separation processes and determine such macroscopic phenomena as adhesion, wetting, and adsorption. Our research focuses on the relationship between the chemical structure and morphology of a surface and its interfacial properties. Our goals are to understand the factors that control interfacial properties at the microscopic level, and to develop general processing methods for modifying the surfaces of materials. Such manipulations when properly developed yield improvements in performance and ease in chemical processing.

To examine the relationships between these various types of interfacial phenomena and surface structure in a well-controlled manner, we rely on recent chemical and materials advances to prepare systems of well-defined two- and three-dimensional architectures. Molecular engineering is applied to generate surfaces and coatings that are tailored with nanoscopic precision. A continued observation has been the remarkable changes at macroscales effected by molecular-scale manipulations to surfaces.

Long surfactant-like molecules can be tailored to adsorb spontaneously onto various supports. This method yields a densely packed assembly of oriented molecules that exposes a surface of chemical functionality to the outside world. By tailoring the molecules used in the assembly, the surface (and thereby its energetics) can be systematically modified. By this method, the relationships between molecular-scale details and macroscopic properties (such as wetting, adhesion, lubrication, adsorption, and corrosion prevention) have been examined. In our research effort, we employ a repertoire that includes organic synthesis, materials preparation, and various methods of surface characterization (Auger, XPS, SIMS, STM/AFM, contact angle measurements, electrochemistry, impedance, etc.). These studies are complemented by the use of these molecular assemblies to address various questions in surface science and in their implementation in molecular-based electronic and optical devices including biosensors.

Such systems have been developed to allow the chemical modification of a broad class of surfaces. Our focus has been primarily on electrode and semiconductor surfaces for the generation of chemical and biosensors, with recent effort examining the connections between inorganic supports and biological systems. These projects include efforts to design surfaces for use in microbioreactors where cell surface contacts and specified molecular recognition are important. Our approaches provide broad scalability to the microscale as the assembling elements are molecules and are insensitive to surface size. Sensors that rely on the presence of a single atom on a surface and polymer films that nucleate due to presence of a single layer of immobilized monomers provide examples of the fine-tuning of our processing.

Recent advances in molecular biology and in DNA synthesis and manipulation in specific afford new possibilities for introducing complex functionality to surfaces by straightforward and well-developed methods. Using these approaches, we have produced a general method for immobilizing oligonucleotides to surfaces with well-defined arrangements. These structures offer potential for allowing quantitative analyses from generated microarrays for both research and diagnosis and for providing a research platform for examining fundamental issues that affect DNA hybridization at surfaces. More broadly, these efforts provide the nucleus for a targeted research endeavor into directing the self-assembly of complex systems. This work involves the introduction of specified surface interactions that can direct the concurrent self-assembly of individual micro and nanoscopic species to form small composite objects without the requirement of additional user-input. Key elements of molecular design drive the study and development of these self-assembling structures.

Another area of interest is the development of dispersible magnetic nanoparticles with tailorable surface chemistries in collaboration with Prof. Alan Hatton from MIT. Magnetic fluids formed from these particles offer high surface areas, short diffusional distances, selectable interactions, and a magnetic handling for manipulation both within the fluid and for removal from a liquid phase. Interests in separation, extractions, and other areas define our work in this area.

Selected Publications

1. Seok-Won Lee and Paul E. Laibinis: "Protein Resistant Coatings for Glass and Metal Oxide Surfaces Derived from Oligo(ethylene glycol)-terminated Alkyltrichlorosilanes", Biomaterials 1998, 19, 1669-1675.
2. G. Kane Jennings, Jeffrey C. Munro, Tseh-Hwan Yong and Paul E. Laibinis: "Effect of Chain Length on the Protection of Copper by n-Alkanethiols," Langmuir 1998, 14, 6130-6139.
3. Mark D. Angelino and Paul E. Laibinis: "Synthesis and Characterization of Polymer-Supported Salen Ligand for Enantioselective Epoxidation", Macromolecules 1998, 31, 7581-7587.
4. Lifen Shen, Paul E. Laibinis and T. Alan Hatton: "Bilayer Surfactant Stabilized Magnetic Fluids: Synthesis and Interactions at Interfaces," Langmuir 1999, 15, 447-453.
5. Namyong Y. Kim and Paul E. Laibinis: "Improved Polypyrrole/Silicon Junctions by Surfacial Modification of Hydrogen-terminated Silicon Using Organolithium Reagents," J. Am. Chem. Soc. 1999, 121, 7162-7163.
6. Seok-Won Lee and Paul E. Laibinis: "Directed Movement of Liquids on Patterned Surfaces Using Non-Covalent Molecular Adsorption," J. Am. Chem. Soc. 2000, 122, 5395-5396.
7. Namyong Y. Kim, Noo Li Jeon, Insung S. Choi, Seiichi Takami, Yoshiko Harada, Krista R. Finnie, Gregory S. Girolami, Ralph G. Nuzzo, George M. Whitesides, and Paul E. Laibinis: "Surface-Initiated Ring-Opening Metathesis Polymerization on Silicon," Macromolecules 2000, 33, 2793-2795.
8. Lifen Shen, Agnieszka Stachowiak, Seif-Edeen K. Fateen, Paul E. Laibinis, and T. Alan Hatton: "Structure of Alkanoic Acid Stabilized Magnetic Fluids: A Small Angle Neutron and Light Scattering Analysis," Langmuir 2001, 17, 288-299
9. Seiichi Takami, G. Kane Jennings, and Paul E. Laibinis: "Composite Monolayer of Copper and Silver on Au(111) by Underpotential Deposition," Langmuir 2001, 17, 441-448.
10. Richard Michalitsch and Paul E. Laibinis: "Adsorption-Mediated Electrochemical Sensing of Halides," Angew. Chem. 2001, 113, 967-970.

CHEMICAL & BIOMOLECULAR ENGINEERING DEPT. MS-362
Rice University PO Box 1892 Houston, Texas 77251-1892	E-mail: chbe@rice.edu	Phone: (713) 348-4902 FAX:(713) 348-5478