Difference between revisions of "Team:Lambert GA/Applied Design"

In order to demonstrate the versatility of electroporators, the underlying mechanism allowing their functioning must first be described. Cell membranes comprise of a combination of proteins, lipids, carbohydrates, and other macromolecule-based structures arranged into a bilayer formation providing a selectively permeable barrier to protect the cell and facilitate the transport of molecules into and out of the cell, thereby reducing the potential for molecules to freely diffuse into a cell (Gennis1989Biomembranes). This theory of the organization of the cell membrane in the formation of a phospholipid bilayer was characterized by Singer and Nicholson and named the “fluid mosaic model”, and the mosaic properties were further characterized as dominant to the fluidic properties (Engelman2005MembranesFluid). Electroporation results in a disruption of membrane integrity (1989ElectroporationBiology, 2008ElectroporationProtocols, Nickoloff1995AnimalProtocols), and the subsequent events following electrical discharge allow for membrane permeabilization (Glaser1988ReversiblePores, Needham1989ElectromechanicalCompressibility, Neumann1972PermeabilityMembranes, Teissie1999ElectropermeabilizationMembranes, YowTsong198725Cells,WeaverElectroporationMechanisms, Zimmermann1976EffectsMembranes, Zimmermann1996ElectromanipulationCells). While the actual molecular occurrences caused by electroporation that allow for DNA uptake are relatively unknown, experimental trials have indicated that interaction between the electrical fields and phospholipids result in the creation of aqueous pores in the membrane (Chernomordik1987ThePhenomenologies, Neu2003ElectricalPores, Benz1979ReversibleStudy), high-voltage pulses stimulate a reorganization in the ions resulting in a new transmembrane voltage producing a local electrical field. These local electrical fields are theorized to lead to the formation of the aforementioned aqueous pores, allowing for the transport of molecules into a cell (Kotnik2010InducedTransport). The totality of these sequence of events contribute to the uptake of DNA by cells in the processes of bacterial electrotransformations, but additionally function in cellular uptake for the other outlined applications of electroporation.

The observation of the effects of electrical pulses on living organisms can be traced back to the late 1700s when German physicist Georg Christoph Lichtenberg described branched structures that form when high-voltage electrical pulses are induced on human skin, which are now referred to as Lichtenberg Figures (Rolong2018HistoryElectroporation). Over 200 years later, it was demonstrated that high-voltage pulses greatly increased the number of transfected cells, leading to the coinage of the term “electroporation”, based on the theory that these pulses induced temporary membrane disruptions allowing for DNA uptake (Neumann1982GeneFields). Over the past decade, electroporation has been increasingly characterized in terms of its electrical and biological functionality, with elements such as field strength, voltage output, arc length, transformation efficiency, etc, leading to more advanced technology utilized to carry out the process. Additionally, an increase in the theoretical understanding behind electroporation’s principles has expanded its applications tremendously, including for cancer therapies through electrochemotherapy and electrically-induced tumor apoptosis, transdermal drug delivery, vaccine delivery, etc (Prausnitz1993ElectroporationDelivery., SuzukiDirectElectroporation, Miklavcic2015ElectrochemotherapyElectroporation, Todorova2017ElectroporationMacaques). This versatility in terms of functionality and applicability for the electroporator indicates its importance in biotechnology and medical fields, and with the inhibitory factors mentioned above limiting its incorporation into labs, schools, and even in field biology, the need for a low-cost portable electroporator has risen greatly.

In contrast with the existing bulky and complex electroporators available commercially, the ElectroPen stems from a basic design incorporating readily available components, including a conventional household stove lighter. It is actuated using a toggle which pushes down the hammer action controlling the force generation on the piezoelectric crystal. The user exerted force allows for the hammer action to proceed through several phases (described below), allowing for discharge of the high-voltage pulse. The casing additionally allows for the attachment of copper wires to those already existing on the crystal, and heat-sensitive insulation is coated on the copper wire to prevent the user from experiencing any electrical shock. The ElectroPen thereby requires no access to electricity, can be fabricated in approximately 15 minutes, is portable, and costs only 23 cents to build*.