Individual Listing

0324 CHEMICAL SCIENCES
University of California
Riverside, CA 92521

Cheng, Quan

Associate Professor of Chemistry

College of Natural and Agricultural Sciences

Chemistry


Biography

 

Degrees

B.S. 1986

Nanjing University (China)

M.S. 1989

Nanjing University (China)

Postdoctor 1995

University of California-Berkeley

Research Area

The focus of our research program is the development of novel detection technologies for biological and pathogenic agents. Much attention is given to applying molecular recognition principles in advancing analytical chemistry techniques dealing with peptides, protein toxins, viruses and bacteria. Fast and sensitive detection of pathogens is of significant importance to many facets of medical diagnostics, food safety, environmental monitoring and anti-biological warfare campaigns. Our approach emphasizes “real-time” detection schemes, and involves the design and synthesis of self-organizing supramolecular assemblies capable of optical or electronic signaling. The overall research effort spans three general areas: biosensors, bio-interfaces, and biomaterials. I. Biosensors: Biosensors are molecule-based devices that transduce a biochemical process or binding event into a measurable signal. A typical biosensor consists of a receptor that defines specificity and a transducer that generates signals. Our biosensor research is directed at establishing effective signal transduction pathways through the functionalization of supramolecular assemblies that simulate cell membranes. Specifically, active cell surface constituents are incorporated into synthetic membrane-mimicking materials that undergo a change in chemical or physical properties upon binding of target molecules. Molecular level techniques are used to fabricate the sensing interface on vesicle bilayers and Langmuir-Blodgett thin films where molecular orientation and packing can be controlled. We are developing two new classes of biosensors: (1) biochromic conjugated polymer (BCP)-based sensors that report pathogen binding by straightforward color change; and (2) redox supramolecular assembly (RSA)-based sensors for amperometric detection of biological targets carrying no electroactive centers. Miniaturization of sensing units is to be carried out using microfabrication techniques. Micro-sensor chips capable of self-calibration and cross-examination are sought to enhance detection sensitivity and lower false positive response rates. The biosensor research concerns the following topics: Langmuir-Blodgett technique for fabrication of monolayer-based thin film sensors. Signal transduction in membrane-mimicking materials. Multivalent toxin interactions on BCP films. "Real-time", direct biosensing of viruses. Electrochemistry of redox supramolecular assemblies and amperometric pathogen sensors. and so on. Some Research Highlights: U.S. Researchers Develop Instant E. coli Test (CNN, 1996) A New Kind of Lipid Forms Shape-Changing Artificial Membranes (Berkeley Lab Currents, 2001) II. Bio-interfaces: To design effective biosensors, the nature of molecular interactions between the target and receptor molecules must be fully understood. We are interested in revealing the mechanisms by which chemical modifications at the interface engender changes in the binding affinity and specificity of the targeted species using surface plasmon resonance (SPR). SPR is a quantum optical-electrical phenomenon capable of sensitive and quantitative measurement of a broad spectrum of chemical and biological entities. Since the phenomenon of SPR is completely non-specific, rational design of the recognition interface for SPR applications is critical. We focus on establishing self-assembled functional monolayers (SAFM) on Au for the kinetic study of ligand-receptor interactions. The analytical aspects of SPR bio-interface study include ultrasensitive detection of pathogens, up to single organism, and micropatterning of the SAFMs for multi-channel measurements. Coupling SPR with other analytical techniques for in situ characterization of complex biological process will also be explored. III. Biomaterials: The ability to precisely control molecular arrangements developed in nanotechnology holds forth the promise of a completely new generation of advanced materials. We are interested in applying nanoscience concepts to the fabrication of bio-inspired new materials addressing various medical and environmental detection needs. Specifically, molecular recognition is combined with nanometer-scale architectural control to generate functional assemblies with desirable bulk properties. We are pursuing chemical approaches for new classes of biomaterials with unusual morphology and novel electro-optical property suitable as transducer elements for biosensors. One example is nanostructured tubular lipid assemblies and nanofibers with controllable orientation. In addition, we are interested in studying the interplay between molecular level properties and nanoscale organization, and the impact of biological functionalization on the formation and structural properties of supramolecular materials.

Publications

Jie Song, Quan Cheng*, Susanne Kopta and Raymond C. Stevens. Modulating Artificial Membrane Morphology: A pH-Induced Chromism and Nanostructural Transformation of a Bolaamphiphilic Conjugated Polymer from Blue Helical Ribbons to Red Nanofibers, J. Am. Chem. Soc. 2001, 123, 3205. Preprint in PDF format

Quan Cheng*, Maki Yamamoto and Raymond C. Stevens. Amino Acid Terminated Polydiacetylene Lipid Microstructures: Morphology and Chromatic Transition, Langmuir2000, 16, 5333. Preprint in PDF format

Tuzhi Peng, Quan Cheng and Raymond C. Stevens. Amperometric Detection of Escherichia coli Heat-Labile Enterotoxin by Redox Diacetylenic Vesicles on a Sol-Gel Thin-Film Electrode, Anal. Chem. 2000, 72, 1611. Preprint in PDF format

Quan Cheng, Tuzhi Peng and Raymond C. Stevens. Signaling of E. coli Enterotoxin on Supramolecular Redox Bilayer Vesicles, J. Am. Chem. Soc.1999, 121, 6767. Preprint in PDF format

Quan Cheng and R.C. Stevens. Charged-Induced Chromatic Transition of Amino Avid-Derivatized Polydiacetylene Liposomes, Langmuir 1998, 14, 1974. Preprint in PDF format

Quan Cheng and Raymond C. Stevens. Coupling of An Induced Fit Enzyme to Polydiacetylene Thin Films: Colorimetric Detection of Glucose, Adv. Mater. 1997, 9, 481.

Deborah Charych, Quan Cheng, Anke Reichert, Geoffrey Kuziemko, Mark Stroh, Jon O. Nagy, Wayne Spevak and Raymond C. Stevens. A ‘Litmus Test’ for Molecular Recognition Using Artificial Membranes, Chemistry & Biology 1996, 3, 113.