We specialize in synthetic bioorganic chemistry with a focus on carbohydrate chemistry, particularly oligosaccharide and glycoconjugate synthesis, as well as synthetic photochemistry.  Our lab engages in two research areas both of which are highly interdisciplinary and collaborative in nature.  Therefore, students have the opportunity to gain project-related knowledge and hands-on experiences beyond synthetic organic chemistry.  Our research projects are as follows:

Carbohydrate Chemistry:

Biomarker Discovery for Chagas Disease and Leishmaniasis and Development of New Diagnostic Tools

The protozoan parasites Trypanosoma cruzi, which causes Chagas disease, and several species of Leishmania, which cause different forms of leishmaniasis, express unusual glycans on their cell surfaces, which are foreign to humans and highly immunogenic.  The trypomastigote form of T. cruzi has glycosylphosphatidylinositol (GPI)-anchored mucin-like glycoproteins on the cell surface, with predominantly branched O-glycans.  With the exception of the linear trisaccharide Galα1,3Gal β1,4GlcNAcα, the exact structures of these glycans are not known, but many of them have terminal a-galactosyl (a-Gal) residues at their non-reducing ends.  Some Leishmania species, e.g. L. major, L. mexicana, and L. braziliensis, all of which cause cutaneous leishmaniasis in different parts of the world, express type-2 glycoinositolphospholipids (GIPLs), which are rich in α-galactopyranosyl and β-galactofuranosyl residues.  The structures of the type-2 GIPLs are well established, but the immunodominant glycotopes, i.e., the portions of the glycan responsible for a strong antibody response, are not known.  In an overall process that we call "Reversed Immunoglycomics", our lab synthesizes parasite-derived glycans, terminal portions of these glycans, or suspected structures based on partial structural information.  These sugars are then conjugated to proteins to form glycoarrays of neoglycoproteins which are used as antigens in chemiluminescent Enzyme-Linked Immunosorbent Assay (CL-ELISA) to identify diagnostic biomarkers.  The ELISA assays are carried out in the laboratories of Drs. Igor Almeida and Rosa Maldonado (Dept. of Biological Sciences, UTEP).  We are interested in utilizing these biomarkers for the development of vaccines (with Drs. Almeida and Maldonado), and highly sensitive and specific diagnostic methods with Dr. Almeida and Dr. Sreeprasad Sreenivasan (Dept. of Chemistry and Biochemistry, UTEP).

Photochemistry as Green Chemistry:

Exploration of the Photochemistry of 7-Nitroindoline Containing Compounds  –  Synthesis and Application

The attractiveness of photochemistry lies in its mild and neutral reaction conditions and in the utilization of light (including sun light) as an unlimited energy source and "activating agent".  Therefore, photochemical methods are considered environmentally friendly alternatives that reduce the need for chemical activators and metal catalysts, and also reduce hazardous waste. 

The unusual photochemical properties of N-acyl-7-nitroindolines have been discovered by Abraham Patchornik and coworkers in the 1970’s.  These compounds undergo photochemical acylation reactions, and photohydrolysis.  We developed 7-nitroindoline-containing linkers suitable for solid-phase peptide chemistry, and photochemical methods to synthesize protected N-glycopeptides, peptide thioesters, and peptide amides under neutral conditions.  We also incorporated nitroindolines into the backbone of a collagen-like peptide, giving it unique photochemical properties.  Photolysis can occur by illumination with near UV light by a one-photon absorption mechanism, or with infrared femtosecond laser light by a two-photon absorption mechanism.  Films or gels of these N-acyl-7-nitroindoline-containing compounds lend themselves to precision micropatterning and have potential applications in biophotolithograpy.  The micropatterning is carried out with a femtosecond laser in the laboratory of our collaborator, Dr. Chunqiang Li (Dept. of Physics, UTEP).  We are also interested in the generation of photoreactive crosslinkers, and in understanding the photolysis mechanism of photoreactive nitroindoline compounds.  For the latter we combine experiment with theoretical calculations in collaboration with Dr. Carl Dirk (Dept. of Chemistry and Biochemistry, UTEP).