Session: Research Posters

Paper Number: 172495

Impact of Hemoglobin-Ion Interaction on the Electrical Properties of Hemoglobin Solutions 

Electrical properties of hemoglobin (Hb) solutions are fundamental properties that provide valuable insights into the health metrics of red blood cells (RBCs). In an equivalent circuit model of a suspending RBC, its intracellular content can be modeled with a resistor. As the electrical conductivity of intracellular Hb solution is primarily influenced by the intracellular salts concentration, ion mobilities, and Hb concentration, understanding the impact of Hb-ion interactions on the electrical properties of Hb solutions can be useful to inform the hydration and Hb concentration of individual RBCs. In this study, we developed a computational-experimental framework for evaluating human Hb solutions, which were prepared from both crystallized and fresh forms of human Hb. Electrical impedance spectroscopy in a microfluidic system that consists of a Polydimethylsiloxane (PDMS) microfluidic channel and interdigitated indium tin oxide electrode chip, was employed to characterize the Hb solutions over a frequency range of 40 Hz to 110 MHz.  As the obtained impedance data consists of not only the impedance of suspending medium but influences of the device under testing, including stray capacitance, lead resistance from electrical connections, as well as the electrical double layer. System calibration was performed by fitting electrical circuit models on deionized water (DI) and ionic buffer of known ionic compositions in simulating cytoplasm composition and further validated by finite element analysis through COMSOL simulation. The results showed that when dissolved in DI, the electrical properties of Hb exhibited an increasing linear trend in conductivity at low concentrations, whereas a polynomial relationship emerged at medium to high concentration levels. In low ionic strength buffers, an initial increase in the total conductivity of the Hb solutions was observed at very low concentrations (0–3 g/L). This behavior can be interpreted as resulting from minimal interaction between hemoglobin and the ions. Given that hemoglobin itself carries a net negative charge, it contributes to the overall conductivity of Hb solutions. When ionic strength further increases, such as in cytoplasm-like environment, Hb interaction with surrounding ions leads to a reduction in the overall electrical conductivity, attributed to ions binding to Hb and reduced ionic mobility. This trend remains consistent across varying concentrations of fresh Hb. On the other hand, Hb solutions prepared from powder exhibited significant variability in impedance data at ionic strengths exceeding 0.024 mol/L, suggesting the formation of a supersaturated and non-homogeneous solution. This method can be extended to analyze Hb variants beyond normal Hb and can also be combined with single cell impedance to inform intracellular Hb content of individual RBCs.   

Presenting Author: Adeleh Kazemi Alamouti Florida Atlantic University

Presenting Author Biography: Adeleh Kazemi Alamouti is a PhD student under supervision of Dr. E(Sarah) Du, Associate professor at Florida Atlantic University, she is currently conducting research in the field of blood impedance spectroscopy focus on determining hemoglobin concentration at single red blood cell level.

Authors:

Adeleh Kazemi Alamouti Florida Atlantic University
E Du Florida Atlantic University