Electrophoretic Transport Through Fibrocartilage Driven by Square and Sawtooth Pulses With Decreased Joule Heating

Measurement of molecular transport through tissues can be performed using gel electrophoresis techniques but is subject to substantial changes of temperature over the course of an experiment due to conversion of electrical to thermal energy. The objective of this study is to mitigate thermal generation and accumulation while determining the electrophoretic mobility of charged molecules within annulus fibrosus cartilage tissue. By using electrical pulses as compared to direct current (DC), less total energy is input and more heat can dissipate in a given amount of time. Temperature measurements confirm that use of DC leads to higher rates of temperature change during electrophoresis, with Joule heating responsible for the thermal rise. The measured electrophoretic mobilities of two small, charged dye molecules are found to be similar among DC, square and sawtooth pulsed electrophoresis. One significant difference occurs between square and sawtooth pulses for the dye that interacts less with the cartilage tissue. Results herein suggest that accurate measurements with reduced temperature changes of thermally-sensitive tissues can be made using pulsed electrophoresis, which can lead to a better understanding of molecular transport under physiological conditions.