Our group has broad research interests in solar energy conversion, bioanalytical chemistry and materials chemistry. Categorized as such, however, our projects are often found more exciting when we can disregard the boundaries or depart our comfort zone for at least a while. Of course, efforts have been consistently made to turn the items in the comfort zone into our expertise, which include electrochemistry, luminescence (spectroscopy and imaging) and microfabrication.
Solar energy can potentially cut our dependence on fossil fuels but current technologies suffer from high cost and low efficiency. To fully tap its potential, significant advancements both in fundamental understanding and technological innovation are needed in capture and storage of solar energy. Our approach to this complex problem is to build a modular thin-film photoconversion model system using solid-supported lipid structures. This is apparently inspired by Nature's tremendous success in building photosynthesis systems using these materials. With our biomimetic approach, fundamental parameters governing the photoconverting performance can be systematically studied and optimized. Conventional monolayer-based photoconversion systems typically rely on the covalent linkage of thiol- or silane-functionalized photoactive conjugates on electrodes, which often require nontrivial synthesis in organic media. By contrast, our approach takes advantage of the versatile assembly of phospholipids in water and potentially provides an alternative approach to modular photoelectrochemical cell design.
Fullerenes have been frequently included in building artificial photoconversion systems owing to their unique electrical and photochemical properties, including their narrow HOMO-LUMO gap, long-lived photoinduced charge separation and low reorganization energy associated with the electron/energy transfer. To facilitate light-to-electrical energy conversion, a stable fullerene-on-electrode structure often needs to be constructed. Because of their extreme hydrophobicity, the handling and chemical modification of fullerenes have been largely limited to organic media. A very interesting alternative is based on the use of amphiphilic species such as surfactants and phospholipids. As these molecules form colloids such as micelle and liposome in water via self-assembly, they can host fullerenes within the hydrophobic region of the final structure. Besides fullerenes, we’re also interested in integrating other novel photoactive agents, such as ruthenium tris(bipyridyl) complexes and porphyrins, into the lipid matrix. Similar successes we’ve had so far clearly points to the generality of this lipid-based approach.
Efforts have also been made in this lab to understand the potential roles lipids can play in order to improve the photoconversion efficiency further. More details on this project can be found in our recent publications.
One of our long-term research goals is to develop integrated chemical systems for sensitive biorecognition and detection. While it seems increasingly easy to achieve high-sensitivity detection nowadays, it remains difficult to do it cheaply and reliably. Thus, we’ve spent a lot of time thinking about multiplexing and signal amplification.
Equally important in achieving sensitive and reliable biological/chemical detection is the mechanisms for signal generation and transduction. To this end, we’re working on new strategies for immobilization of biomaterials on electrodes so that inexpensive electrochemical readouts can be carried out at the end. Importantly, electrochemistry-based detection schemes also bear a great potential in simultaneous detection of multiple analytes. In this case, our experience in microfabrication and patterning comes in handy.
Research is also underway in this lab to develop new detection techniques that are inexpensive to operate than fluorescence but bear the same kind of sensitivity. Check out our publications for the latest results in this area.
Our current research in materials chemistry focuses on phospholipid-based systems for biosensing and solar energy conversion. Lipids can be either directly extracted from natural sources or synthesized from widely available starting materials. More importantly, lipids combine several appealing characteristics that make them ideal building blocks in constructing integrated chemical systems. First, they are used by Nature to form cell membranes of all organisms, hosting molecular machineries including numerous cell receptors and photosynthesis system complexes. Second is their versatile assembly. Lipids can form stable microscopic colloid particles, such as liposomes, in solution and bilayer structure on solid support surfaces. These assembled structures can be further controlled in terms of size, bilayer thickness and fluidity. Third, chemical modification to these lipids can be made with great flexibility so that structures with additional functionalities can be obtained. These new functional groups, in turn, provide additional means for bioimmobilization, the first step in building biosensors. Last but not least, the assembled acyl chains of lipids form a 2-dimensional oleophilic environment in which many hydrophobic molecules can be dissolved or inserted. This offers a completely different mechanism for integration and thus increases the overall complexity of the system. Please check out our recent publications in this area for more information.
26. Liu, L.; Zhan, W. “Molecular Photovoltaic System Based on Fullerenes and Carotenoids Co-Assembled in Lipid/Alkanethiol Hybrid Bilayers.” Langmuir, 2012, 4877-4882.
25. Xie, H.; Jiang, K.; Zhan, W. “A Modular Molecular Photovoltaic System Based on Phospholipid/Alkanethiol Hybrid Bilayers: Photocurrent Generation and Modulation.” Phys. Chem. Chem. Phys., 2011, 17712-17721.
24. Song, N.; Zhu, H.; Jin, S.; Zhan, W.; Lian, T. “Poisson-Distributed Electron-Transfer Dynamics from Single Quantum Dots to C60 Molecules.” ACS Nano, 2011, 613-621.
23. Zhan et al. “Photocurrent Generation from Porphyrin/Fullerene Complexes Assembled in a Tethered Lipid Bilayer.” Langmuir, 2010, 15671-15679.
22. Jiang, K.; Xie, H.; Zhan, W. “Photocurrent Generation from Ru(bpy)32+ Immobilized on Phospholipid/Alkanethiol Hybrid Bilayers.” Langmuir, 2009, 11129-11136.
21. Zhan, W.; Jiang, K. “A Modular Photocurrent Generation System Based on Phospholipid-Assembled Fullerenes.”Langmuir, 2008, 13258-13261.
20. Yu, Y.; Zhan, W.; Albrecht-Schmitt, T. E. “[H2bipy]2[(UO2)6Zn2(PO3OH)4(PO4)4]·H2O: An Open-Framework Uranyl Zinc Phosphate Templated by Diprotonated 4,4´-bipyridyl.” Inorg. Chem., 2008, 9050-9054.
19. Alsobrook, A. N.; Zhan, W.; Albrecht-Schmitt, T. E. “On the Use of Bifunctional Phosphonates for the Preparation of Heterobimetallic 5f-3d Systems.” Inorg. Chem., 2008, 5177-5183.
18. Nelson, A. G. D.; Bray, T. H.; Zhan, W.; Albrecht-Schmitt, T. E. “Further Examples of the Failure of Surrogates to Properly Model the Structural and Hydrothermal Chemistry of Transuranium Elements: Insights Provided by Uranium and Neptunium Diphosphonates.” Inorg. Chem., 2008, 4945-4951.
17. Jiang, K.; Zhang, H.; Shannon, C.; Zhan, W. “Preparation and Characterization of Polyoxometalate/ Protein Ultrathin Films Grown on Electrode Surfaces Using Layer-by-Layer Assembly.”Langmuir, 2008, 3584-3589.
16. Yu, Y.; Zhan, W.; Albrecht-Schmitt, T. E. “One- and Two-Dimensional Silver and Zinc Uranyl Phosphates Containing Bipyridyl Ligands.” Inorg. Chem., 2007, 10214-10220.
15. Zhan, D.; Li, X.; Zhan, W.; Fan, F.-R. F.; Bard, A. J. “Scanning Electrochemical Microscopy. 58. The Application of a Micropipette-Supported ITIES Tip to Detect Ag+ and Study Its Effect on Fibroblast Cells.” Anal. Chem. 2007, 5225-5231.
14. Zhan, W.; Bard, A. J. “Electrogenerated Chemiluminescence. 83. Immunoassay of Human C-Reactive Protein (CRP) by Using Ru(bpy)32+ Encapsulated Liposomes as Labels.”Anal. Chem., 2007, 459-463.
13. Bard, A. J.; Li, X.; Zhan, W. “Chemically Imaging Living Cells by Scanning Electrochemical Microscopy.” Biosens. Bioelect. 2006, 461-472.
12. Zhan, W.; Bard, A. J. “Scanning Electrochemical Microscopy. 56. Probing Outside and Inside Single Giant Liposomes Containing Ru(bpy)32+.”Anal. Chem., 2006, 726-733.
11. Zhan, W.; Crooks, R. M. “Microelectrochemical Logic Circuits.”J. Am. Chem. Soc., 2003, 9934-9935. (Highlighted by Chemical & Engineering News, Sep. 1 2003, Nature Materials Sep. 2003 and Analytical Chemistry Oct. 1 2003)
10. Zhan, W.; Alvarez, J.; Sun, L.; Crooks, R. M. “A Multichannel Microfluidic Sensor that Detects Anodic Redox Reactions Indirectly Using Anodic Electrogenerated Chemiluminescence.” Anal. Chem., 2003, 1233-1238.
9. Zhan, W.; Alvarez, J.; Crooks, R. M. “A Two-Channel Microfluidic Sensor that Uses Anodic Electrogenerated Chemiluminescence as a Photonic Reporter of Cathodic Redox Reactions.” Anal. Chem., 2003, 313-318.
8. Zhan, W.; Alvarez, J.; Crooks, R. M. “Electrochemical Sensing in Microfluidic Systems Using Electrogenerated Chemiluminescence as a Photonic Reporter of Electroactive Species.” J. Am. Chem. Soc., 2002, 13265-13270.
7. Zhan, W.; Seong, G. H.; Crooks, R. M. “Hydrogel-Based Microreactors as a Functional Component of Microfluidic Systems.” Anal. Chem., 2002, 4647-4652.
6. Seong, G. H.; Zhan, W.; Crooks, R. M. “Fabrication of Microchambers Defined by Photopolymerized Hydrogels and Weirs within Microfluidic Systems: Application to DNA Hybridization.” Anal. Chem., 2002, 3372-3377.
5. Zhan, W.; Wang, T.; Li, S. F. Y. “Derivatization, Extraction and Concentration of Amino Acids and Peptides by Using Organic/Aqueous Phases in Capillary Electrophoresis with Fluorescence Detection.” Electrophoresis, 2000, 3593-3599.
4. Zhan, W.; Xu, Y.; Li, A.; Zhang, J.; Schramm, K. M.; Kettrup, A. “Endocrine Disruption by Hexachlorobenzene in Crucian Carp (Carassius auratus gibelio).” B. Environ. Contam. Tox., 2000, 560-566.
3. Zhan, W.; Wang, T.; Li, S. F. Y. “Coupling of Solvent Semimicroextraction with Capillary Electrophoresis Using Ethyl Acetate as Sample Matrix.” Electrophoresis, 2000, 573-578.
2. Zhang, D. N.; Zhou, Z. P.; Tang, Y. Z.; Wu, C. Y.; Zhan, W.; Xu, Y. “Analysis of Organchlorine Compounds in Water by Solid Phase Microextraction and Gas Chromatography.” Chinese J. Anal. Chem., 1999, 768-772.
1. Zhang, D. N.; Zhou, Z. P.; Tang, Y. Z.; Wu, C. Y.; Zhan, W.; Xu, Y. “Sol-gel method for the preparation of solid-phase microextraction fibers.”Anal. Lett., 1999, 1675-1681.
Thanks for your visit!
I’ve come into my fourth year at Auburn. Before taking my current position, I spent six years in the Lone Star State, first getting my Ph.D. (Advisor: Richard M. Crooks, Texas A&M University) and then as a postdoctoral fellow in Al Bard’s lab at University of Texas at Austin.
I’ve had all-around training in analytical chemistry. I started out my M.S. studies in China by analyzing environmental samples with GC, HPLC and GC/MS. Then I spent two years on capillary electrophoresis for various applications. In my Ph.D. work at Texas A&M, I developed microfluidics-based sensing and networking strategies where I became acquainted with fluorescence microscopy and electrochemistry. Of course, in Al Bard’s lab at Austin, I greatly deepened my understanding in electrochemistry and also had the chance to play with his beloved scanning electrochemical microscope (SECM).
Also in Austin, I resumed my exercise as a soccer striker in Al’s group. Our weekly opponents, most of the times, are the guys (sometimes girls) of my former (Crooks) group, who then relocated themselves to Austin. With strong and skillful oversea players from France, Spain and Cameron, Crooks squad is hell of a team to beat. I continued my soccer games for about a year at Auburn and then decided to quit because of the arrival of my son, Austin (pictured above at 1 month), and other responsibilities as a starting professor.
My name is Hong (Sherry) Xie and I joined Dr. Zhan’s group in 2007. I’m interested in new solar conversion strategies.
My name is Lixia (Lisa) Liu and I joined Dr. Zhan's research group in the Fall of 2008. My research is focused on bioanalytical/materials chemistry.
My name is Ana and I joined Dr. Zhan's research group in the Fall of 2011. I'd like to explore lipids based photoelectrochemistry and bioanalytical chemistry in this group.
Hi! I'm Brad and I'm in my second year at Auburn. I want to develop my career in biomedicine and currently, I'm feeling proud to run my own project on lipid-based biomaterials in Dr. Zhan's lab. War eagle!
Hi! I'm Alex and I'm a junior chemistry student at Auburn. I'm pretty good at skateboarding and like to learn some solar energy related chemistry in Dr. Zhan's lab.
Hi! I'm Andrew and I'm a junior chemistry student at Auburn. I'm pretty good at skateboarding too!
Postdoctoral researcher '07-'10, Current employment: Professor, Huangzhong University of Science and Technology, Wuhan, China
Visiting Scholar '10-'11, Current employment: Associate Professor, Wuhan University, Wuhan, China
Postdoctoral researcher '11-'12, Current employment: Postdoctoral researcher, Texas A&M
March 16, 2010
Our research on solar energy conversion gets funded by the NSF (through a CAREER award to W.Z.). We're grateful for their recognition and generous support.