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A biosensor is an analytical device, used for the detection of a chemical substance, that combines a biological component with a physicochemical detector. The sensitive biological element, e.g. tissue, microorganisms, organelles, cell receptors, enzymes, antibodies, nucleic acids, etc., is a biologically derived material or biomimetic component that interacts with, binds with, or recognizes the analyte under study. The biologically sensitive elements can also be created by biological engineering. The transducer or the detector element, which transforms one signal into another one, works in a physicochemical way: optical, piezoelectric, electrochemical, electrochemiluminescence etc., resulting from the interaction of the analyte with the biological element, to easily measure and quantify. The biosensor reader device connects with the associated electronics or signal processors that are primarily responsible for the display of the results in a user-friendly way. This sometimes accounts for the most expensive part of the sensor device, however it is possible to generate a user friendly display that includes transducer and sensitive element. The readers are usually custom-designed and manufactured to suit the different working principles of biosensors.
Nanosensors are nanoscale devices that measure physical quantities and convert these to signals that can be detected and analyzed. There are several ways proposed today to make nanosensors; these include top-down lithography, bottom-up assembly, and molecular self-assembly. There are different types of nanosensors in the market and in development for various applications, most notably in defense, environmental, and healthcare industries. These sensors share the same basic workflow: a selective binding of an analyte, signal generation from the interaction of the nanosensor with the bio-element, and processing of the signal into useful metrics.
Colloidal gold is a sol or colloidal suspension of nanoparticles of gold in a fluid, usually water.The colloid is usually either an intense red colour or blue/purple . Due to their optical, electronic, and molecular-recognition properties, gold nanoparticles are the subject of substantial research, with many potential or promised applications in a wide variety of areas, including electron microscopy, electronics, nanotechnology, materials science, and biomedicine.
Thioredoxin reductases are the only known enzymes to reduce thioredoxin (Trx). Two classes of thioredoxin reductase have been identified: one class in bacteria and some eukaryotes and one in animals. In bacteria TrxR also catalyzes the reduction of glutaredoxin like proteins known as NrdH. Both classes are flavoproteins which function as homodimers. Each monomer contains a FAD prosthetic group, a NADPH binding domain, and an active site containing a redox-active disulfide bond.
A nanoparticle or ultrafine particle is usually defined as a particle of matter that is between 1 and 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm, or fibers and tubes that are less than 100 nm in only two directions. At the lowest range, metal particles smaller than 1 nm are usually called atom clusters instead.
An immunoassay (IA) is a biochemical test that measures the presence or concentration of a macromolecule or a small molecule in a solution through the use of an antibody (usually) or an antigen (sometimes). The molecule detected by the immunoassay is often referred to as an "analyte" and is in many cases a protein, although it may be other kinds of molecules, of different sizes and types, as long as the proper antibodies that have the required properties for the assay are developed. Analytes in biological liquids such as serum or urine are frequently measured using immunoassays for medical and research purposes.
Phosphoribosyl pyrophosphate (PRPP) is a pentose phosphate and a biochemical intermediate in the formation of purine nucleotides via inosine-5-monophosphate. Hence it is a building block for DNA and RNA. The vitamins thiamine and cobalamin, and the amino acid tryptophan also contain fragments derived from PRPP. It is formed from ribose 5-phosphate (R5P) by the enzyme ribose-phosphate diphosphokinase:
Tryptophan hydroxylase (TPH) is an enzyme (EC 1.14.16.4) involved in the synthesis of the neurotransmitter serotonin. Tyrosine hydroxylase, phenylalanine hydroxylase, and tryptophan hydroxylase together constitute the family of biopterin-dependent aromatic amino acid hydroxylases. TPH catalyzes the following chemical reaction
Annexin A5 is a cellular protein in the annexin group. In flow cytometry, annexin V is commonly used to detect apoptotic cells by its ability to bind to phosphatidylserine, a marker of apoptosis when it is on the outer leaflet of the plasma membrane. The function of the protein is unknown; however, annexin A5 has been proposed to play a role in the inhibition of blood coagulation by competing for phosphatidylserine binding sites with prothrombin and also to inhibit the activity of phospholipase A1. These properties have been found by in vitro experiments.
An artificial enzyme is a synthetic organic molecule or ion that recreates one or more functions of an enzyme. It seeks to deliver catalysis at rates and selectivity observed in naturally occurring enzymes.
Gamma-butyrobetaine dioxygenase is an enzyme that in humans is encoded by the BBOX1 gene. Gamma-butyrobetaine dioxygenase catalyses the formation of L-carnitine from gamma-butyrobetaine, the last step in the L-carnitine biosynthesis pathway. Carnitine is essential for the transport of activated fatty acids across the mitochondrial membrane during mitochondrial beta oxidation. In humans, gamma-butyrobetaine dioxygenase can be found in kidney (high), liver (moderate), and brain. BBOX1 has recently been identified as a potential cancer gene on the basis of a large-scale microarray data analysis.
In enzymology, a kynurenine-oxoglutarate transaminase is an enzyme that catalyzes the chemical reaction
Magnetic nanoparticles are a class of nanoparticle that can be manipulated using magnetic fields. Such particles commonly consist of two components, a magnetic material, often iron, nickel and cobalt, and a chemical component that has functionality. While nanoparticles are smaller than 1 micrometer in diameter, the larger microbeads are 0.5–500 micrometer in diameter. Magnetic nanoparticle clusters that are composed of a number of individual magnetic nanoparticles are known as magnetic nanobeads with a diameter of 50–200 nanometers. Magnetic nanoparticle clusters are a basis for their further magnetic assembly into magnetic nanochains. The magnetic nanoparticles have been the focus of much research recently because they possess attractive properties which could see potential use in catalysis including nanomaterial-based catalysts, biomedicine and tissue specific targeting, magnetically tunable colloidal photonic crystals, microfluidics, magnetic resonance imaging, magnetic particle imaging, data storage, environmental remediation, nanofluids, optical filters, defect sensor, magnetic cooling and cation sensors.
Morpheeins are proteins that can form two or more different homo-oligomers, but must come apart and change shape to convert between forms. The alternate shape may reassemble to a different oligomer. The shape of the subunit dictates which oligomer is formed. Each oligomer has a finite number of subunits (stoichiometry). Morpheeins can interconvert between forms under physiological conditions and can exist as an equilibrium of different oligomers. These oligomers are physiologically relevant and are not misfolded protein; this distinguishes morpheeins from prions and amyloid. The different oligomers have distinct functionality. Interconversion of morpheein forms can be a structural basis for allosteric regulation. A mutation that shifts the normal equilibrium of morpheein forms can serve as the basis for a conformational disease. Features of morpheeins can be exploited for drug discovery. The dice image represents a morpheein equilibrium containing two different monomeric shapes that dictate assembly to a tetramer or a pentamer. The one protein that is established to function as a morpheein is porphobilinogen synthase, though there are suggestions throughout the literature that other proteins may function as morpheeins.
Polyvalent DNA gold nanoparticles, now more commonly referred to as spherical nucleic acids, are colloidal gold particles densely modified with short, highly oriented, synthetic DNA strands. They were invented by Chad Mirkin et al. at Northwestern University in 1996. Paul Alivisatos et al. at the University of California, Berkeley introduced a related monovalent structure the same year. Due to the strong interaction between gold and thiols (-SH), the first polyvalent DNA gold nanoparticles were obtained by capping the gold nanoparticles with a dense monolayer of thiol-modified DNA. The dense packing and negative charge of the phosphate backbones of DNA orients it into solution with a footprint that is dependent on factors including the particle size and radius of curvature.
Spherical nucleic acids (SNAs) are nanostructures that consist of a densely packed, highly oriented arrangement of linear nucleic acids in a three-dimensional, spherical geometry. This novel three-dimensional architecture is responsible for many of the SNA's novel chemical, biological, and physical properties that make it useful in biomedicine and materials synthesis. SNAs were first introduced in 1996 by Chad Mirkin’s group at Northwestern University.
A biotransducer is the recognition-transduction component of a biosensor system. It consists of two intimately coupled parts; a bio-recognition layer and a physicochemical transducer, which acting together converts a biochemical signal to an electronic or optical signal. The bio-recognition layer typically contains an enzyme or another binding protein such as antibody. However, oligonucleotide sequences, sub-cellular fragments such as organelles and receptor carrying fragments, single whole cells, small numbers of cells on synthetic scaffolds, or thin slices of animal or plant tissues, may also comprise the bio-recognition layer. It gives the biosensor selectivity and specificity. The physicochemical transducer is typically in intimate and controlled contact with the recognition layer. As a result of the presence and biochemical action of the analyte, a physico-chemical change is produced within the biorecognition layer that is measured by the physicochemical transducer producing a signal that is proportionate to the concentration of the analyte. The physicochemical transducer may be electrochemical, optical, electronic, gravimetric, pyroelectric or piezoelectric. Based on the type of biotransducer, biosensors can be classified as shown to the right.
Throughout human history, fungi have been utilized as a source of food and harnessed to ferment and preserve foods and beverages. In the 20th century, humans have learned to harness fungi to protect human health, while industry has utilized fungi for large scale production of enzymes, acids, and biosurfactants. With the advent of modern nanotechnology in the 1980s, fungi have remained important by providing a greener alternative to chemically synthesized nanoparticle.
A copper nanoparticle is a copper based particle 1 to 100 nm in size. Like many other forms of nanoparticles, a copper nanoparticle can be formed by natural processes or through chemical synthesis. These nanoparticles are of particular interest due to their historical application as coloring agents and the biomedical as well as the antimicrobial ones.
Christa L. Brosseau is a Canadian chemist, currently a Canada Research Chair at Saint Mary's University (Halifax). Brosseau's research focus is on Electrochemical Surface-Enhanced Raman Spectroscopy.
References
- ↑ Sanderson, Katharine (23 March 2010). "Nanoparticle kit could diagnose disease early". Nature . doi:10.1038/news.2010.143.
