Graduate Exam Abstract

yusra obeidat

Ph.D. Preliminary
April 27, 2018, 11:15 am - 12:45 pm
Mechanical Engineering Conference Room
A Multi-Sensor Platform for Measuring Single_Cell Metabolism to Improve Success Rate of Assisted Reproductive Technology (ART)

Abstract: Cell metabolism involves a set of cellular chemical reactions that are very important to cell development as well as its response to environmental changes around the cell. Understanding cell metabolism and the associated metabolic pathways has been the focus of many research efforts and it is gaining more attention recently. In assisted reproductive technology (ART), understanding metabolism of oocytes and embryos provides the possibility of selecting more viable embryos for transfer and reducing the number of embryos transferred in a given IVF cycle. Although stage-specific morphologic markers and grading systems have been developed and widely in use, this approach is unable to reliably assess the physiological status of the embryo and it is not only subjective but has a poor correlation with subsequent developmental competence. Therefore, there is an ever-increasing need for noninvasive quantitative markers of embryo viability. Analysis of metabolism has proved to be a valuable marker of embryo viability based on animal models. Through noninvasive analysis of viability markers, it will be feasible to identify those embryos with the highest probability of establishing a healthy pregnancy. Crucial to cell metabolic process is a set of analytes that can be used as indicators of cell metabolism. They include oxygen, glucose, and lactate. However, techniques for measuring dissolved oxygen (DO) traditionally rely on fluorescent labels. Traditional techniques for measuring glucose uptake and lactate production during cells metabolism are also based on fluorescent labels. These techniques have their drawbacks including photobleaching and cytotoxicity and they are incredibly labor intensive and pipet construction is complex comparing with solid state and electrochemical methods. Injecting a cell with fluorescent label can also lead to experimental error, since biochemical mechanisms inside of the cell may interact with the label. Due to the lack of quantitative and real-time monitoring of cell metabolism, the success rate of in-vitro fertilization (IVF) is still low, with very low percentage of embryos transferred resulting in a term pregnancy. Therefore, more work needs to be done for testing embryos metabolism in-vitro to improve the culture conditions and reduce the effect of environmental stresses and chose the media that balance all nutrients the cell needs during development. In this proposal, a multi-sensor platform has been proposed for measuring single cell metabolism to improve success rate of assisted reproductive technology. The proposal presents the development of a multi- sensors system to measure concentrations of DO, pH, glucose, and lactate concurrently at single cell level in real-time. DO was measured amperometrically using a three-electrode system of working (WE), counter (CE) and reference (RE) electrodes. pH was measured potentiometrically using two electrodes system of Indium Tin Oxide (ITO) WE and Au pseudo RE. Glucose and lactate were measured enzymatically by measuring the current generated from the oxidation of hydrogen peroxide generated from the catalysis of glucose or lactate at the WEs with their catalysis enzymes. A micro-chamber containing all four sensors was designed and manufactured to investigate single cell immersed in up to 120 µL of respiration medium. The micro-chamber design is an important part of the platform that provides sufficient changes of the target analytes in the micro-environment that enables the sensors to measure tiny changes of the target analytes due to cell respiration. This setup helps to measure the analytes with a change in concentration ranges from (0.001 to 10) fmol/s with high specificity which is comparable with what was published in literature. The specificity of our sensors was clearly determined by monitoring the switch in metabolism to glycolysis induced by adding oligomycin as an inhibitor for ATP-synthase, The preliminary results show that the embryos metabolism change with development as expected and the amounts of glucose and oxygen uptakes and lactate production increase at higher stages of developments which match the existing biological knowledge about metabolism of increasing the need for ATP production at higher stages of development. Moreover, this preliminary work includes the study of the effect of enzymes layers on cells morphology and development and the modification of the enzymes contents to make them more compatible and reduce their toxicity on oocytes and embryos in long-term development. The importance of our work came from the need for real- time measurement of multiple metabolites in addition to the change in pH level during cell metabolism. the platform of our multi-sensors system allows tracking the embryo development in the same chamber and the change of metabolic activity during development. The analysis of all analytes as well as the change in pH level at the same time can give better insight to the "switch" in metabolism induced by inhibitors such as oligomycin, and at the different time points of embryo development. Previously, different studies focused on the analysis of glucose, lactate and oxygen of mammalian embryos using fluorescence techniques. This multi-sensor system has some potential applications include evaluating effects of metabolic therapies on oocyte bioenergetics, study the effect of aging on embryos development and monitoring mitochondrial function throughout oocyte maturation and blastocyst development to predict embryo viability to compliment assisted reproductive technologies.

Adviser: Tom Chen
Co-Adviser: N/A
Non-ECE Member: Stuart Tobet , Department of Biomedical Sciences
Member 3: Sudeep Pasricha, ECE
Addional Members: Goerge Collins, ECE

accepted: Y. Obeidat, T. Chen, Characterization of an O2 Sensor Using Microelectrodes. ‎IEEE Sens. Orlando, FL, Oct. 30 – Nov. 2, 2016, [].
submitted: Obeidat, Y.; Evans, A.; Tedjo, W.; Chicco, A.; Carnevale, E.; Chen, T. Monitoring Oocyte/Embryo Respiration Using Electrochemical-Based Oxygen Sensors. Preprints 2017, 2017120060 (doi: 10.20944/preprints 201712. 0060.v1).

Program of Study:
Grad 550