Research Goals
In order to determine the effects of hydrogel delivery of hydrogen sulfide, we must first develop gelatin microspheres of the appropriate dimension. Once the microspheres are created, time-release profiles of hydrogen sulfide will be characterized from microspheres fabricated with acidic or basic gelatin, and at varying cross-linkages. In a separate experiment, sodium hydrogen sulfide (NaHS), a salt from which hydrogen sulfide is created in solution, will be added to cell cultures in a dose-response test to determine the most effective concentration of NaHS for biological viability. The culminating step is to load the best concentration of NaHS (as determined by the dose-response test) into gelatin microspheres (fabricated according to the best time-release profile) and examine its effects on heart viability.
Research Progress
The team is finishing up cell studies, having finished in vivo experiments, and is doing immunohistochemistry on samples that have been collected. Our past research efforts involved successfully developing the materials necessary to investigate controlled release of hydrogen sulfide, which includes microsphere fabrication, cross-linking, loading with NaHS, and preliminary investigations of hydrogen sulfide release from microspheres over time.
Microspheres
Following a modified version of the protocol for microsphere fabrication as described in Tabata, et al. (1999), we have been able to successfully fabricate gelatin microspheres. Although microsphere varies across trials, we have been able to produce microspheres with an average diameter as small as 7 microns. Our goal is to consistently achieve an average diameter below 10 microns in order to avoid capillary blockage.
We are also experimenting with varying concentrations of gluteraldehyde to cross-link the fabricated microspheres. Since cross-linkage may affect release rates of NaHS, the proper concentration of gluteraldehyde must be determined in order to achieve the desired time-release profile.
Hydrogen Sulfide
Experiments with loading sodium hydrogen sulfide into microspheres are also underway. Varying concentrations of NaHS solution, diluted from a 25 mM stock solution, are carefully loaded into microspheres through overnight incubation. All protocols involving NaHS and hydrogen sulfide are carried out under the hood because hydrogen sulfide is a toxic gas.
Once microspheres are loaded release over time is determined by the zinc acetate assay. We have a time-release profile between NaHS concentration and release.
Papers & Presentations
Proposal, last updated March 31, 2009
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Proposal Defense Presentation, from April 3, 2009
Transcript of Proposal Defense, from April 3, 2009
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Junior Colloquium Presentation, from November 10, 2009
Thesis Defense Presentation, from April 2, 2011
Final Thesis, last updated April 26, 2011
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