Electrokinetic Biosensing at a Liquid-Liquid Interface

Electrokinetics;Biosensing;Microfluidics;Chemical & Biomolecular Engineering

Mavrogiannis, Nicholas G.Gagnon, Zachary ;

Johns Hopkins University

关键词: Electrokinetics;    Biosensing;    Microfluidics;    Chemical & Biomolecular Engineering;   

Others  :  https://jscholarship.library.jhu.edu/bitstream/handle/1774.2/37264/MAVROGIANNIS-THESIS-2014.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: JOHNS HOPKINS DSpace Repository

【 摘 要 】

Development of low-cost, rapid, sensitive and portable biosensing systems are important for the detection and prevention of disease in developing countries, biowarfare/anti-terrorism applications, environmental monitoring, point-of-care diagnostic testing and for basic biological research. Currently, the most established commercially available and widespread assays for portable point of care detection and disease testing are paper-based dipstick and lateral flow test strips. These paper-based devices are often small, cheap and simple to operate. The last three decades in particular have seen an emergence of these assays in diagnostic settings for the detection of pregnancy, HIV/AIDS, blood glucose, Influenza, urinary protein, cardiovascular disease, respiratory infections and blood chemistries. Such assays are widely available largely because they are inexpensive, lightweight, portable, are simple to operate, and a few platforms are capable of multiplexed detection for a small number of sample targets.In this paper, we present, in three parts, the first non-optical technique for detecting and quantifying chemical and biomolecular reactions in solution phase. First, an interfacial tilt is explored utilizing Maxwell-Wagner (MW) stress. Two fluids of varying electrochemical properties, conductivity and permittivity, are forced to flow side by side. When an electric field is applied across the interface a liquid displacement occurs across the interface. This displacement is found to be frequency dependent. At low frequency, roughly 1 MHz, the fluid with a higher conductivity displaces into that of a lower conducitivity. On the contrary, at high frequencies, roughly 20 MHz, the fluid with the high permitivitty displaces into the fluid with a lower permitivitty. The frequency in which no displacement occurs is known as the crossover frequency (COF). Next, for ion and biodetection, the interface created between these two streams is comprised of one liquid containing the analyte of interest and a second liquid containing a receptor. Analyte-receptor binding at the interface changes the interfacial electrical polarizability, and this change in polarizability can be detected by measuring the physical interfacial ;;tilt” during exposure to the AC electric field. The frequency-dependence of this displacement is highly sensitive to receptor:ligand binding at the interface, and by measuring this displacement as a function of frequency, the presence of an analyte can be determined. When a reaction occurs downstream the channel, the COF of the system increases, yet when no reaction occurs, the COF decreases down the channel, due to diffusion. Advisor: Dr. Zachary GagnonReader: Dr. Joelle Frechette