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Microfluidic Based Biosensors and Applications
Published in Sibel A. Ozkan, Bengi Uslu, Mustafa Kemal Sezgintürk, Biosensors, 2023
Münteha Nur Sonuç Karaboğa, Mustafa Kemal Sezgintürk
With their history of more than 30 years, aptamers are in increasing demand due to their advantages such as their stable three-dimensional structure and folding ability, which allows them to interact with target molecules through electrostatic interactions, hydrogen bonding, Van der Waals forces and electrostatic interactions. Aptamers, which are synthetic oligonucleotides (DNA or RNA) that bind to chemical and biological analyte targets through affinity interactions, can be developed for a variety of analytes such as small molecules, proteins and cells through an in vitro production process (75–77). Rapid advances in RNA and DNA synthesis have made possible the use of aptamers that offer high-affinity biomolecular recognition to a theoretically limitless variety of analytes. DNA and RNA aptamers compete with more established affinity ligands, including most immunoreceptors such as enzymes, lectins and antibodies, and are gaining more interest in biosensor studies. The high specificity of aptamers has also made it desirable for integration into microfluidic devices (77).
Engineered Extracellular Vesicle-Based Therapeutics for Liver Cancer
Published in Peixuan Guo, Kirill A. Afonin, RNA Nanotechnology and Therapeutics, 2022
An advantage of using RNA scaffolds attached to the EV surface is that it can provide the basis for incorporation of targeting or detection oligonucleotides. Aptamers are single-stranded RNA or DNA oligonucleotides with small molecular weight that can bind to and recognize specific target molecules. The formation of 3D structures enables them to bind strongly to targets on cancer cells without the involvement of covalent bonds and thus makes them suitable for use for cell surface molecule targeted therapy (Zhou and Rossi 2014; Lundin, Gissberg, and Smith 2015). Aptamers can be generated using Systematic Evolution of Ligands by Exponential Enrichment (SELEX) approaches, which were first described in the early 1990s and which enabled chemically synthesized oligonucleotides with minimal batch variation (Tuerk and Gold 1990; Ellington and Szostak 1990). The use of RNA aptamers for clinical applications has been challenged by their susceptibility to nuclease degradation in biological systems. Aptamer stabilization can be provided by using 2ʹ-F modifications and thereby provide stability and enhance function when used in clinical settings (Binzel, Khisamutdinov, and Guo 2014; Piao et al. 2018). With these design considerations, RNA aptamers to desired targets could be incorporated onto the membranes of EVs to generate a targeted delivery system.
Chemical Imaging with Fluorescent Nanosensors
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2020
Seren Hamsici, Robert Nißler, Florian A. Mann, Daniel Meyer, Sebastian Kruss
Developments in RNA/DNA synthesis and functionalization have led to the idea of selecting new nucleic acid-based recognition units called aptamers (Tombelli et al. 2007). Aptamers are either single-stranded DNA or RNA molecules containing 20-80 nucleotides and can be selected for different targets starting from a huge library of molecules containing randomly created sequences for targeting purposes (Tombelli et al. 2005). These small-structured RNAs have the ability to bind to viral or host proteins with high affinity and specificity and also lots of features such as small size, flexibility, chemical simplicity, and reversible denaturation make aptamers superior when compared with other receptors like antibodies (Sullivan 2002). In order to make aptamers gain a high affinity for target molecules, a selection process called systematic evolution of ligands by exponential enrichment (SELEX) was discovered (Tuerk & Gold 1990). This strategy allows the isolated aptamers to recognize cells without prior knowledge of the target molecules. Aptamers selected by these new SELEX techniques bind to certain molecules with high affinity and specificity and they can also be chemically modified with relative ease (Du et al. 2015; Wu et al. 2014).
Determination of carcinoembryonic antigen (CEA) by surface plasmon resonance-enhanced total internal reflection ellipsometry (SPRe-TIRE)
Published in Instrumentation Science & Technology, 2023
Aslı Erkal-Aytemur, Samet Şahin, Zafer Üstündağ, İbrahim Ender Mülazımoğlu, Mustafa Oguzhan Caglayan
An alternative diagnostic element to improve analytical selectivity and sensitivity is aptamers[19,20] that are single-stranded DNA or RNA oligonucleotides selected from a random or homologous library and been developed for various analytes since their first reports in 1994.[21,22] They are versatile recognition elements since they interact with the target showing as good affinity as the antibody-antigen interactions.[23] Aptamers also have advantages over antibodies such as stability, low cost, and ease of production.[24] Aptamers have been developed for the selective determination of CEA in various media with good sensitivity and selectivity, high accuracy, fast response, and low cost.[25–28]
Aptamer-based technology for radionuclide targeted imaging and therapy: a promising weapon against cancer
Published in Expert Review of Medical Devices, 2020
Luca Filippi, Oreste Bagni, Clara Nervi
Aptamers are constituted by single-strand artificial oligonucleotides sequences of DNA, RNA, or modified RNA. Their peculiar property is folding and forming three-dimensional structures, capable of interacting and specifically binding to target molecules, with an affinity in the nanomolar/sub-nanomolar range, similar to that of monoclonal antibodies (MoAb). It has to be highlighted that, respect to MoAbs, aptamers present several advantages: easier production and lower cost, lower immunogenicity, possibility of chemical synthesis and modification and, most interestingly, the property of refolding after denaturation, thus going back to the desired tridimensional (3D) configuration [2]. A wide range of aptamers can be generated through the evolutionary engineering method called systematic evolution of ligands by exponential enrichment (SELEX). However, aside SELEX, other approaches have been recently incorporated into the selection protocol to improve the efficiency of high-affinity aptamer-production [2,3].
Label-free sensitive detection of MUC1 using a liquid crystal based-system
Published in Liquid Crystals, 2020
Thai Duong Song Duong, Chang-Hyun Jang
Aptamer technology has experienced a surge in popularity over the last few decades, and they have emerged as useful highly specialised molecules that can recognise, bind and hamper a specified target [14]. Aptamers are DNA or RNA ligands, selected for high affinity and specificity for their targets. Aptamers have been developed to recognise proteins and receptors [15,16], as well as small molecules [17]. The affinity of the aptamer to their target can compete with that of antibodies, as their dissociation constants can be as low as in the picomolar range [18]. Aptamers have been used in various sensing technologies, including luminescence [19], fluorescent [20–22], electrochemical [12,23], and colorimetric [24,25].