Date of Award

2020

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Chemical Engineering (PhD)

Administrative Home Department

Department of Chemical Engineering

Advisor 1

Adrienne R. Minerick

Committee Member 1

David R. Shonnard

Committee Member 2

John J. Durocher

Committee Member 3

Rebecca G. Ong

Abstract

Worldwide, an estimated 31% of people who die each year have a cardiovascular disease (CVD), an all-encompassing group of diseases and conditions of the heart or blood vasculature. Access to portable, user-friendly tools to test lipid levels accurately and efficiently, without requiring large volume blood draws, will help improve access to wellness management by reducing costs and facilitating early screening and monitoring of CVD thus improving outcomes. Point of care micro or millifluidic chips to test biofluids that are integrated into detection units are an attractive measurement tool because of their potential for ease of use by patients at home or at satellite limited function clinics.

This dissertation outlines four research efforts aligned with the larger goal of CVD detection: 1) use laboratory equipment and microdevice measurements to compare the lipid profile content of fasting plasma and blood samples to post-meal samples to determine an optimal method to rapidly detect lipid levels, 2) compare the optimal detection method, UV-Vis spectroscopy, against gold-standard medical laboratory tests, 3) examine the effects of tea consumption (Hibiscus sabdariffa tea or Camellia sinensis (Oolong tea)) and a peach tea control on blood lipid profiles and cardiovascular metabolic indicators, 4) design and test a millifluidic chip, miniaturizing the optimal technology from Objective 1, to detect the lipemic state using a drop or two of blood plasma.

The overarching hypothesis guiding this dissertation research was given that low-density lipoproteins of large and small lipid globules directly affect plasma turbidity, optical and electrical measurements can be simplified into a portable, point-of-care unit to discern high- and low-density lipoproteins and triglyceride levels in human blood samples for lipemia diagnosis or other CVD risk determinations. This dissertation focused on detecting the transient lipemic state; however, this work could serve as a foundation to eventually discern chronic cholesterol levels using a simpler approach than current medical tests.

The new knowledge gained from this dissertation includes a simple dilution-based, reagent-free method to discern lipemic status in donated blood samples. A ratiometric analysis was conducted such that lipemic status could be discerned with a 99% confidence from a single unknown sample. These results are partially corroborated with UV-Vis lipoprotein standards as well as a gold-standard medical tool, HPLC-MS. Additional knowledge was gained regarding the time-dependent reduction in lipid profiles of participants consuming Hibiscus and Oolong teas as compared to the peach tea control. While the participant study was interrupted due to COVID-19 lab closures, the data obtained provides preliminary suggestive evidence that these teas do influence lipid profiles over time. A new device was also engineered to demonstrate portable lipid testing.

Future work will involve measuring cholesterol levels in different human body liquids such as tears, urine, skin, and saliva since research has been initiated into the ability to use fluids other than blood (plasma or serum) for diagnostic testing. Using other bio-fluids may make the test less invasive and less costly as well for the patient.

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