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Bioelectronics is a broad field of research in the convergence of biology and electronics. It is characterized as the integration of organic and biological materials with electronic components. Through evolution, organisms have created the most effective catalysts in the form of enzymes. Nature has also produced biomolecules with optimal recognition and binding capabilities such as antibody-antigen and hormone-receptor pairs. Modern biotechnology has allowed humans to modify and create new novel biomolecules which can apply principles developed by evolution to help solve engineering problems. Nano and micro scale engineering have produced electronic devices with highly tailorable structures and properties. These advances have created a broad platform of functional units for integration between biological materials and electronic elements. This integration can produce technologies that utilize biomolecules to alter electronic components to respond to changes in a biological environment as well as utilize electronic units to activate biomaterials toward desire functions. Applications of bioelectronics include biosensing, medical imaging, biofuel cells, biocomputing, nanoscale mechanical devices, prosthetics, and other medical applications.

The National Institute of Standards and Technology (NIST) defines “drivers” as targeted bioelectronic technology applications. Bioelectronic technologies and devices can be utilized to detect and prevent diseases, and develop prosthetics. For example, conducting polymers are being utilized in biomedical devices like implanted electronics and in vitro devices, and biosensors are being utilized to sense enzymes, antibodies, and nucleic acids [3D nanostructured…..devices]. These technologies can further research into various diseases such as cancer and neurodegenerative diseases. Another related driver in the field of bioelectronics is prosthetics. This includes neural prosthetics such as cochlear implants and artificial retinas, as well as biochemical prosthetics such as artificial tissues and organs. These drivers motivate research and innovation in the field of bioelectronics.

Biosensing

 * Main Article: Biosensor

There are numerous biological systems that are sought to be analyzed by bioelectronic means. For example, electronic devices integrated with proteins can be used to rapidly detect the presence of various metabolic products in a sample of body fluid. It is thought that measurement devices that utilize biomolecules can be used to quickly and accurately collect data both in vitro and in vivo and can allow for rapid chemical testing that does not require full laboratory setups.

An example of a bioelectronic technology used in biosensing is electrically contacted enzymes.

Enzymes have been used to catalyze the reaction of particular molecules into detectable products. Enzymes can also be used as labels in binding assays that use antibodies and binding proteins as their catalytic activity can amplify the chemical signaling of the system, allowing for extremely sensitive assay methods. The primary method used to produce enzymatic biosensors is to couple redox enzymes with electrodes.

Current uses of enzyme electrodes are in the detection of low molecular weight metabolites, such as glucose. Blood glucose meters for patients with diabetes utilize disposable test strips on which are screen printed enzyme electrodes. Each strip contains a working and reference electrode, with the working electrode coated with the reagents, such as enzymes, mediators, stabilizers, and linking agents. These disposable strips, paired with a hand-held computer and display, are used to display the concentration of blood glucose. This is a prime example of the use of bioelectronic principles to provide individuals with diagnostic tools without the need of a laboratory.

Biofuel Cells

 * Main Article: Microbial Fuel Cell

Biofuel cells are electrochemical systems that utilize biological components or bacteria to drive an electrical current. This involves transferring electrons from the cell’s fuel source into the anode of an electrochemical cell. Charge balance is maintained by ionic movement within the cell. Microbial fuel cells are a type of biofuel cell that transfers the energy of bacterial activity in an electron-donating fuel to drive a current, and can be either mediated or unmediated. Another type of biofuel cell involves using electrically contacted enzymes to activate redox reactions to directly harvest electrons from an electron donor. Many biofuel cells utilize an organic electron donor such as glucose or acetate. Waste biomass such as lactic acid and other biologically produced material such as ethanol are attractive fuels for biofuel cells. Through the use of bio-catalysts, the reduction of oxygen and the oxidation of biofuels can be driven without the need for rapid combustion. One attractive use for biofuel cells is to provide power for biomedical applications such as pacemakers, prosthetics, and in vivo biosensors which can use blood glucose as a fuel source.

Electrochemical DNA Sensors
Nucleic acid bases undergo redox processes at electrodes. It was first discovered in 1955 by E. Chargaff and J.N. Davison that adenine is reducible at mercury electrodes where other nucleic acid bases are inactive. Several studies occurred in the decades following their experiments, testing nucleic acids by electrochemical methods using differing electrodes and it was found that nucleic acids undergo reduction and oxidation processes at electrodes. It was also found that electrochemical signals of long chain DNA and RNA molecules are significantly influenced by their higher ordered structures. This means that electrochemical means can be used to detect damage in the double-helix structures of DNA as well as structural changes in nucleic acids. Electrochemical DNA sensors can indicate differences in native and denatured DNA; their measurements may be used to find strand breaks, unmatched nucleic acid base pairs, and damage to bases. These methods can be particularly useful in drug analysis, and allow researchers and healthcare providers to understand the effects that many anticancer drugs will have on a patient's DNA. In this way, health care providers can better understand what medications may perform well in treatment, but do the least harm to a patient.

Molecular Optobioelectronics
Researchers are developing methods by which they might initiate a biochemical reaction using light signals. The structure of molecules can be changed without changing the composition by utilizing certain photographic processes to convert signals, such as a pulsing pattern of light with a certain wavelength or energy, to cause chemical reactions to occur on the surface of the biomaterial. Some of the methods that have been developed include the chemical modification of proteins by photoisomerizable units, the application of photoisomerizable inhibitors, and the immobilization of enzymes in photoisomerizable polymers. The term photoisomerizable refers to molecules which exhibit a reversible behavior in which structural changes in isomers occur, caused by photoexcitation. Photocurrent generation can be read by modified electrodes and translated through some biorecognition processes to produce readouts that allow scientists to determine what biochemical reactions are occuring on the interface. One application of this technology is in information storage. Depending on the optical signal received, a biomolecule will change into a particular isomer and will not change again unless given a different signal.