1019A Poster - 16. Techniques and technology
Thursday April 07, 2:00 PM - 4:00 PM

Authors:
Abby Matt ¹; Hongwu Liang ¹; Matthew Fishman ¹; Andrey Komarov ¹; Xinyuan Zhang ¹; Jing Men ¹; Elena Gracheva ¹; Alex Savtchenko ²; Chao Zhou ¹

Affiliations:
1) Washington University in St. Louis, St. Louis, MO; 2) University of California San Diego, San Diego, CA

Keywords:
b. live imaging; j. cardiovascular disease

Current methods of cardiac stimulation, such as electrical stimulation, ultrasound stimulation, and cardiac optogenetics have certain risks or drawbacks. The use of invasive surgical procedures to implant electrodes and electrochemical reactions caused by electrode-tissue contact may cause serious detrimental effects. In this study, we implement a stimulation technique in the fruit fly Drosophila melanogaster heart that uses graphene injection to optically modulate cardiac activity. Graphene is a single layer arrangement of carbon molecules with unique electrical properties. We prepare a homogenized graphene solution for injection into the heart tube with a combination of phosphate buffer saline (PBS) or artificial hemolymph (AH). PBS and AH were also injected as control solutions. From the graphene solution, optical stimulation excites graphene particles that coat the heart tube, which in turn creates electrical stimulation, changing the membrane potential of heart tube muscles. Through the use of an Optical Coherence Microscopy (OCM) system, custom red light simulation, and a machine learning based model for analysis, we demonstrate non-contact cardiac stimulation after injecting graphene-based biointerfaces into the heart. Further, the analysis of heart mechanics, such as fractional shortening, indicates that there is no change to the way the heart moves when stimulated. This system is promising for studies of various gene-related cardiovascular diseases or for testing drugs. For example, it could enable studies of various cardiovascular differences in Drosophila caused by human ortholog gene mutations.