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Biosensors: A Biotechnological Tool for Monitoring Environmental Pollution
Published in Rouf Ahmad Bhat, Moonisa Aslam Dervash, Khalid Rehman Hakeem, Khalid Zaffar Masoodi, Environmental Biotechnology, 2022
Irteza Qayoom, Zulaykha Khurshid Dijoo, Mehvish Hameed
Immunosensors work on the principle of antigen and antibody interaction (North, 1985; Long et al., 2013). Surface immobilization of antibodies is an important step in the formation of biosensors, and may also cause loss of function in the case of nonoriented immobilization. Nonoriented immobilization results from arbitrary immobilization and steric hindrance due to high antibody density (Karyakin et al., 2000; Grieshaber et al., 2008). Biorecognition process consists of firm binding of antibody to antigens resulting in the formation of complexes. Among five classes of antibodies (IgA, IgD, IgE, IgG, and IgM), IgG is extensively employed for the detection of heavy metals, due to their superior affinity and specificity. Antibodies like monoclonal, polyclonal, or recombinant can be used as biorecognition component in biosensors. Monoclonal antibodies are specific as it binds to a specific antigen. While as polyclonal antibodies have affinity for numerous binding sites contrary to a lone antigen which causes it to bind strongly to the target. Recombinant antibodies are fashioned by genetic engineering technology (Ferrigno, 2016). High sensitivity plus specificity with marginal cross-reactivity are indispensable characteristics of the antibodies for recognition and measurement of targets precisely (Ferrigno, 2016). In order to immobilize antibodies on the sensor, surface covalent binding, noncovalent immobilization plus coupling interfaces are necessary as immobilization is the main phase that shapes the best working of an Immunosensor (Sharma et al., 2016). The activity of the antibodies can also be influenced by the reaction settings like temperature, pH, and ionic strength (Dzantiey and Zherdev, 2013). In electrochemical biosensors, a variation in the electric properties in the space between two electrodes occurs as a result of antigen–antibody responses (Katz and Willner, 2003).
An Overview of Immunoassays
Published in Richard O’Kennedy, Caroline Murphy, Immunoassays, 2017
Caroline Murphy, Sarah Gilgunn, Richard O’Kennedy
The myriad of immunosensing possibilities presented in this chapter are just a taste of the sensing capabilities that are on offer today. Firstly, the type of antibody for a particular application must be taken into account, and, due to their ‘ease-of-manipulation’ and capacity for sensitivity improvement, renders recombinant antibodies increasingly attractive.
Design of an effective piezoelectric microcantilever biosensor for rapid detection of COVID-19
Published in Journal of Medical Engineering & Technology, 2021
Hannaneh Kabir, Mohsen Merati, Mohammad J. Abdekhodaie
The human immune system responds to virus invasion by producing immunoglobulin molecules (antibody) to neutralise the viral antigen. There are three types of antibodies created in response to infection; IgA, IgG, and IgM; antibodies rise and fall at different times after the onset of infection. In usual, IgG is the choice to be measured in most antibody tests as it lasts for the longest time and may reflect longer-term immunity. Like other infectious diseases, B-lymphocytes secrets some types of antibody especially IgM in the acute phase which is found in lymph fluid, blood, and plasma cells as the first antibody. Its protective function is temporary and remains for a short time [1]. Scientists demonstrated that about 48% of the patients, produced IgM antibody in the first week of infection while nearly 96% of them, have it two weeks later [15]. Therefore, it is not an appropriate agent for diagnosing patients in the early phase, particularly in two weeks of symptoms onset. According to the above-mentioned features and for simpler modelling, IgG has been selected to be coated on the biosensor surface and binds the COVID-19 virus through its antigen. IgG is the most abundant and the smallest antibody that is produced by white blood cells. IgG is secreted and identified in serum 7 days after symptom onset. Its concentration begins to rise gradually and peaks during 21th–25th day at 16.47 µg/ml and remains at its high level for about 4 weeks [32,33]. It is a Y-shaped monomer with a molecular weight of 150 kDa [34]. In the current study, the specific COVID-19 antibody could be collected in two ways; 1-Convalescent plasma, 2-Recombinant antibodies (rAbs). Convalescent plasma contains high specific antibodies against antigens of SARS-Cov-2. Now, it has therapeutic uses in COVID-19 patient treatment and it could be utilised as diagnostic agents in the future, as well [35–37]. Monoclonal antibodies (mAbs) are homogenous collections of antibodies that are identical in their protein sequences. Recombinant antibodies are monoclonal antibodies that are produced in vitro by using synthetic genes. Once mAbs with the desired specificity has been developed, it must be produced in a large amount as practical medicines for therapeutic uses. Recently, scientists have developed recombinant monoclonal antibodies that recognise S and N protein of SARS-Cov-2, specifically [38–40].