Instruction Tools for Signal Processing and Machine Learning for Ion-Channel Sensors

1.1 Importance of the Study of Ion-Channels

The study of ion-channels is embedded in several undergraduate and graduate-level bioscience, bio-engineering, and medical science curricula (Demir. 2006). Understanding ion-channels helps in understanding living systems at the cellular level. Cellular membranes are inherently non-permeable to ions. Ion-channel proteins form gated pores across these cell membranes and regulate the flow of ions (Miller 1992, Purves et.al., 2008). They are formed by proteins in living cells and are important in physiological functions such as transport of nutrients, nerve excitation, muscle contraction, and hormonal secretion (Chrispeels et. al., 1999, Goodman 2008). Disorders in the functioning of ion-channels can lead to several diseases (Hatta et.al., 2002) and mutation of the ion-channel proteins. These are the primary causes of abnormal excitation of cells. Mutations can occur in the promoter region (Chakravarthy et. al., 2004, Cooper and Jan, 1999, Ravichandran et.al., 2011) which leads to over-expression or under-expression of the channel protein. Mutations in the coding region can lead to gain or loss of channel function. Abnormalities in the ion transport across channels can cause diseases such as Bartter syndrome. In addition, certain ion-channel forming proteins can act as lethal agents and are often part of the venom of snakes. Ion channels, and their close relative nanopores, are also very useful in DNA sequencing (Ali et.al 2010). More recently, research efforts have demonstrated the utility of ion channels in detecting the SARS-CoV-2 virus that causes COVID-19 (McClenaghan et. al., 2020). The study of ion-channels can provide substantial insight into the cause of several diseases.

As computation models for ion-channel analysis continue to improve, interactions with new molecules and compounds have been discovered and used in fields such as bioengineering and pharmacology. The utility of biologically engineered ion-channels for sensing has been studied in (Braha et.al., 2000, Gu et.al., 1999). Ion-channel proteins have been used to analyze pharmaceutically important substances and to aid in the detection of harmful elements potentially released by chemical weapons.

Due to switching or gating properties, ion-channel proteins produce characteristic current signals (Catterall, 2010). These current signals can be evaluated and analyzed using standard signal processing methods. In (Spanias et. al., 2007a, Konnanath et al., 2009a), the authors describe several statistical signal analysis tools to analyze ion channel currents and ion channel noise.