Tulane University School of Science and Engineering
Summer MAterials Research @ Tulane (SMART)
Research Experience for Undergraduates
Below we describe sample projects offered by faculty advisors under Materials for Health. These representative projects highlight the general interests of the participating faculty, though the specifics may be subject to change.
Materials for Health
Multifunctional Photoreactive Hydrogels for Neural Microengineering
Michael J. Moore, Biomedical Engineering
We are developing novel hydrogels whose physical and chemical properties can be changed with incident light, to serve as the basis for models of neuronal axon guidance and as preclinical models for drug development and toxicity screening. By exploiting variable bandwidth sensitivity of different functional groups, we are developing materials whose responses may be tailored by exposure to different wavelengths of light. The gels enable the relatively simple, yet precise, control of cell microenvironments—specific tissue geometries, regional matrix stiffness, and the placement of soluble and immobilized biomolecules. The models systems we are developing are useful for investigating the precise manners in which axons grow in response to multiple cues in their microenvironment, which are not fully understood. These systems are also being developed as higher-throughput, “nerve-on-a-chip” models of peripheral nerve physiology, neurological diseases, and central nervous system synaptic connections. Models such as these will be employed for drug discovery and toxicity screening, filling an important gap between traditional cell culture preparations and animal studies.
Liposomes and Polymer Breath Figures for Drug Delivery
Vijay John, Chemical and Biomolecular Engineering
Polymer breath figures are thin films containing honeycomb structured surface pores. They are formed by the condensation of water droplets in an evaporating polymer solution, in analogy to the condensation of droplets obtained by breathing on a cold metal surface. The pores are roughly hemispherical allowing them to be filled with slow release systems such as liposomes, and with drugs. We are exploring the use of these films for a number of biomedical applications in controlled drug delivery. For instance, we work with an ophthalmologist and a biochemist at the Tulane Medical Center to develop coatings for glaucoma drainage devices. Such devices allow drainage of fluid from the eye to relieve internal pressure, but become plugged with fibroblast cells. Our coatings contain antifibrolytic agents and allow the glaucoma drainage devices to operate efficiently. Other examples of polymer breath figure coatings are being studied in connection with antibiotic surgical meshes. Finally, we also work extensively with liposomes for drug delivery and for biolubrication, integrating liposomes into breath figures and attaching DNA to liposomes to form lipoplexes for malaria vaccine development. Students working on these projects will learn valuable skills in electron microscopy, drug delivery, liposome and polymer film fabrication. The projects involve use-inspired fundamental work in collaboration with scientists at the medical school and with faculty in physics, chemistry and the life sciences. Students will also learn aspects of technology translation through participation in scale-up and manufacturing aspects. A novel aspect of the research is the extension of the use of breath figure polymer films to the development of new energy storage devices.
Porphyrinic Nanospheres with Attenuated Aromatic-stacking for Biological Imaging
Janan Jayawickramarajah, Chemistry
Porphyrins and their congeners are highly attractive fluorophores for loading onto functional nanoparticles that can be used to interrogate/image biological systems since these macrocycles possess attractive photo-physical properties (including intense absorption in the visible and strong fluorescence). However, in practice, when porphyrinoids are incorporated into nanostructures, especially in aqueous environments, they tend to aggregate via aromatic stacking leading to vastly diminished photo-physical properties including decreased photon absorption and fluorescence. Janan Jayawickramarajah’s lab is developing methods based on supramolecular and polymer chemistry to preclude aromatic stacking of the porphyrin chromophores whilst incorporating them into biocompatible, non-toxic, nanospheres. Student participants will synthesize novel water soluble porphyrin analogs and incorporate them into nanospheres. These will include cyclodextrin linked porphyrin dimers to increase conjugation and enhance the absorption of the porphyrins at longer wavelengths where there is less absorption from endogenous biomolecules and deeper light penetration. Participants will help prepare porphyrins appended to a mono-alkyne arm and three water soluble polymer arms. These porphyrin monomers will have attenuated aromatic stacking due to the appended polymer chains. As the project progresses, students will have opportunities to transfect cells with the nanospheres and evaluate their localization and imaging capabilities.
Developing 3-dimensional Microenvironments for Studying Neuronal Cell Response to Extracellular Tau
A. S. Robinson and J. N. L. Albert, Chemical and Biomolecular Engineering
The cellular microenvironment is of paramount importance to cell function and health since cells are not singularly responsive to chemical signals. Ultimately, the cellular responses to external stimuli may be altered by conducting 3-dimensional culture as opposed to those observed on a tissue culture plate. Synthetic scaffolds fabricated from biocompatible and functionalizable polymers provide an exciting route to creating such environments with tunable chemical and mechanical properties. The Albert group investigates the morphologies of phase separating blends of biocompatible polymers to create nano- and micro-structured materials for various applications, including cell culture. The Robinson group studies protein expression in native and non-native environments and investigates protein trafficking and aggregation. One particular protein of interest is tau, which is implicated in Alzheimer’s disease progression. A student working on this joint project between the Albert and Robinson labs will fabricate 3-dimensional scaffolds suitable for supporting neuronal cells and utilize their scaffolds to investigate how the 3-dimensional microenvironment affects cell behavior in vitro.