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Essay / Ion Transport Essay - 630
Ion transport through pores at the nanoscale is a common process in various biological phenomena. Ion channels, in particular, play an important role in physiological functions such as generating electrical activity in nerves and muscles, regulating cell volume, intracellular signaling, etc. Defective ducts have been linked to a wide range of diseases. For example, abnormal sodium channels in muscle cell membranes cause hyperkalemic periodic paralysis and abnormal potassium channels cause cardiac arrhythmia. It is also known that dysfunction of chloride channels is the cause of cystic fibrosis. Several other disorders are caused by defective ion channels such as epilepsy, diabetes, ataxia and hypertension [bagal, Shieh, Choi]. Drug discovery to restore the proper behavior of defective ion channels is a challenging problem due to the wide variety of channel types as well as their complex behavior. The aim of our study is to relate the mechanism of ion transport in biological channels to molecular level characteristics and to provide a quantitative understanding of the processes responsible for the functioning of ion channels. This is an area widely recognized as needing development. Ultimately, this will make it possible to design new drugs and treatments that will restore the proper functioning of mutated channels. Ion transport also has new applications in medical technology. It has been shown that measuring the ion gating signal of different nucleotides translocating across a pore can form the basis of a rapid DNA sequencing technique [symposium, Clarke]. This technique does not require expensive sample preparation or enzyme-dependent amplification, and will therefore significantly reduce the time required to middle of paper. Solid state nanopores show that when ions pass through the pores their hydration layers are distorted. When the pore diameter is very small, the hydration layer must be removed when the ion passes through the pore. The energy cost associated with partial removal of the hydration layer results in scaled features in the ionic conductance as a function of pore radius [dehydration, Josi]. We want to examine this process in graphene nanopores. The dehydration of ions in these pores is interesting for multiple reasons: 1) the dynamics of the process, in addition to energetics, should play an important role due to the small size and 2) these pores will allow the systematic study of the factors contributing to a complex biological ion channel. Additionally, these pores can be manufactured much more precisely and lead to better controlled experiments...