Roger M. LeBlanc
Professor, Physical Chemistry

Ph.D., Universite Laval, 1964
Postdoctorate, Davy Faraday Research Laboratory, 1968-70

E-mail: rml@umiami.ir.miami.edu

Link to my laboratory website:
http://umchemistry.cox.miami.edu/leblanc

Our research group aims at understanding the surface chemistry, spectroscopic and microscopic investigation of organic and biological supramolecular complexes. The chemistry of monolayers of supramolecular complexes is of paramount importance on account of many potential applications in diverse fields such as manufacture of new polymers, bio- and chemisensors, protective surface coatings, conductive films, optoelectronic devices, etc.

Specifically we are focusing on:

• Combinatorial chemistry

• Molecular recognition

• Development of chemi- and biosensors

• Tissue engineering

• Aggregation studies regarding amyloidogenesis

I. Combinatorial chemistry

We are exploring the novel idea of using 2D combinatorial chemistry methodology to recognize toxin molecules, to catalyze special reactions, and to mimic function of enzymes.

peptide           linker                                  hydrophobic tail

By a combination of different peptide length, sequence and linker, we are interested in screening the amphiphilic peptide lipids library to discover the leading amphiphilic lipids with the best binding affinity or the best catalytic effect to mimic enzymes.

                                   
II. Molecular recognition

The molecular recognition process at biomembrane interfaces plays a crucial role in biological systems. Another long-term objective of our group is to understand the molecular interaction and recognition phenomenon at air/water interface. Specifically, we are studying the interactions between enzymes (OPAA, OPH) and organophosphorus compounds in monolayers. This project funded by a federal agency ultimately aims at developing a sensitive biosensor using enzyme monolayers for the detection of traces of pesticides in aqueous solutions. The detection method is based on photonics.

III. Development of chemi- and biosensors

The long term goal of this project is to develop an optical fiber sensing device to detect the presence of toxins (marine toxin) by fluorescence emission. The major goals are: i) to optimize fluorescence response and selectivity of a chemical sensor to a toxin through molecular recognition , ii) to prepare a sensor derivative and incorporate into an organized assembly such as a monolayer at air/water interface and evaluate the response in 2D array, and iii) to synthesize a molecular sensor suitable for covalent attachment and study the response to toxins.

IV. Tissue engineering

Photocrosslinking provides an effective and benign method for in situ gelation. Facile photogelation exhibits considerable advantages lacked by conventional chemical methods. We are preparing hydrophilic polymers such as PEG, dextran, chitosan macromers with photosensitive groups such as anthrancene and nitrocinnamate. Our preliminary results show that the synthesized macromers can form hydrogel very quickly upon longwave UV irradiation. Additionally, some of these polymers exhibit photoreversibility . These hydrogels will be highly promising in biotechnical and biomedical applications ranging from controlled drug delivery and enzyme immobilization to size-selective biomembranes and wound healing dressings.

V. Aggregation studies regarding Amyloidogenesis

Amyloidogenesis is a very important factor in developing Alzheimer's Disease (AD). AD is known as a progressive neurodegenerative disease that has been the focus of many research endeavors over the few last decades. AD is known to form the so called amyloid plaque which is formed by extracellular aggregates of protein affecting the brain parenchyma and the neurofibrillary tangles which are intracellular aggregates composed of paired helical filaments of hyperphosphorylated tau protein. Surface chemistry is known to be a biomimetic model that can mimic biological systems. Its methodology can be used to study structure conformations, molecular orientation and membrane diffusion. The advantage of surface chemistry is the use of the air-water interface where the molecules will assemble in a similar way as in a biological membrane. We are proposing a two-dimensional biomimetic approach to the amyloidogenesis. The reason for this approach is that biomimetic studies performed to date are done in solution, but since the cleavage of the ß-amyloids takes place at a biointerface it seems logical to study the amyloidogenesis in 2-D. Our approach is based on the possibility of designing peptides or peptide libraries that can assemble in protein-like structures or aggregates. We can assemble in the ßA(1-40) or ßA(1-42) peptide a fluorescent aminoacid that would enhance contrast in the visualization of the amyloidogenesis by means of intrinsic fluorescence; this would, therefore, not require the addition of octadecanoylamino fluorescein to enhance the contrast.

Full List of Publications