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Spectral Self-Interference Fluorescence Microscopy to Study Conformation of Biomolecules with Nanometer Accuracy
Published in Sarhan M. Musa, Nanoscale Spectroscopy with Applications, 2018
Xirui Zhang, Philipp S. Spuhler, David S. Freedman, M. Selim Ünlü
DNA microarrays have been widely used in gene expression profiling, biomarker detection, drug discovery, single-nucleotide polymorphism (SNP) detection, and sequencing, all benefiting from the high-throughput capacity of the technology [76–78]. A routinely used detection process of DNA microarrays and other biosensing technologies is the hybridization of surface-immobilized single-stranded DNA (ssDNA) with solution-phase complementary strands or the binding of dsDNA to target protein molecules. The distance of the probe to the solid surface, the surface hydrophobicity and charge, and physical steric hindrance of the probes influence the accessibility of surface-immobilized molecules for contact with target molecules in solution. The closer the probe molecules are to the solid support, the less likely for the target to reach the probe diffusively Hydrophobic surfaces can act like a shield for bound molecules positioned close to it because of the associated steric factors and lack of diffusion of the bound molecules [79–83]. A charged surface can either repel or attract molecules through electrostatic interactions [84–86]. It has been known that high DNA probe density does affect hybridization kinetics and efficiency, largely due to electrostatic repulsion between DNA strands and steric hindrance [87–89]. Thus, understanding the conformation of surface-bound DNA probes is of great value not only for the future development of DNA microarrays but also for other nanotech-nologies that utilize surface-immobilized DNA oligomers as sensing or actuation agents [90–92].
Optical Fiber Sensors
Published in Krzysztof Iniewski, Smart Sensors for Industrial Applications, 2017
Rogério Nunes Nogueira, Lúcia Maria Botas Bilro, Nélia Jordão Alberto, Hugo Filipe Teixeira Lima, João de Lemos Pinto
With tapered fibers, the evanescent field not only extends beyond the cladding, but its magnitude is also enhanced in that tapered region. When a liquid medium is placed at the tapered region, mode coupling changes the magnitude of the evanescent field, which can be monitored through sensor output. The evanescent field strength is also determined by the diameter and the taper geometry. Regarding tapers as biosensors, Souza et al. [21] performed a chemical treatment of a taper allowing the attachment of the covalent protein (isolated from Staphylococcus aureus cell surface). It is common to combine the use of tapers and surface plasmon resonance (SPR) methods. Leung et al. [22] presented a biosensor that consists of a taper coated with gold and is housed in a flow cell. For the detection of single-stranded DNA (ssDNA), authors showed that it was feasible to directly detect the hybridization of ssDNA to its complementary strand immobilized on the sensor surface. They also presented a similar study for the continuous detection of various concentrations of bovine serum albumin (BSA) and of the target BSA in the presence of a contaminating protein, ovalbumin (OVA) [23].
Fabrication of Sensors for Electrochemical Determination
Published in Jagriti Narang, Chandra Shekhar Pundir, Biosensors, 2017
Jagriti Narang, Nitesh Malhotra, Chandra Shekhar Pundir
The first DNA-based biosensor was investigated by Millan and Mikkelsen in 1993 [37]. A DNA biosensor is based on the principle of immobilization of a single-stranded DNA (ssDNA) on an interface, which combines with its complementary sequence according to Chargaff’s rule and form a hybrid. After the interaction of the probe and its complementary sequence, some detectable change is produced, which can be in the form of current [38], light [39], and resonance [40]. DNA and immuno-based biosensors bind specifically to their target analytes. DNA-based biosensors offer many advantages over other biosensors since interactions between complementary sequences are very specific and robust. Different methods are employed in DNA-based biosensors for the detection of target analytes, such as direct electrochemistry of DNA, redox-active species as labels for hybridization detection, and electrochemical amplifications with nanoparticles.
Activated sludge and UV-C254 for Sapovirus, Aichivirus, Astrovirus, and Adenovirus processing
Published in International Journal of Environmental Health Research, 2023
Chourouk Ibrahim, Salah Hammami, Nesserine khelifi, Pierre Pothier, Abdennaceur Hassen
Because the pathogen prefers subclinical infections, the Aichivirus (AiVs) is an enteric agent that only causes a small percentage of gastroenteritis outbreaks (Rivadulla and Romalde 2020). AiVs is a member of the Picornaviridae family and the Kobuvirus genus. It is a small, non-enveloped virus with an icosahedral-symmetric capsid. Its single-stranded RNA gene codes a poly (A) chain and a positive-sense (8280 nucleotides). In the AiVs genome, there was a 50 untranslated region (UTR) with 744 nucleotides, an internal ribosomal entry site (IRES) that promoted the direct translation of the polyprotein, and a viral genomic protein (VPg) that replaced the methylated nucleotide cap structure; and a poly (A) tail, 237 nucleotides of the 30 UTR region, and an open reading frame (ORF) (Sabin et al. 2016; Zhu et al. 2016). Aichivirus A (formerly known as Aichi virus), Aichivirus B (Bovine Kobuvirus), Aichivirus C (Porcine Kobuvirus), Aichivirus D (Kagovirus from black cattle), Aichivirus E (Rabbit picornavirus), and Aichivirus F (Bat Kobuvirus) are the six recently renamed species that are the genus Kobuvirus (Adams et al. 2017; Zell 2017; Rivadulla and Romalde 2020).
Condensation sampler efficiency for the recovery and infectivity preservation of viral bioaerosols
Published in Aerosol Science and Technology, 2021
Jodelle Degois, Marie-Eve Dubuis, Nathalie Turgeon, Marc Veillette, Caroline Duchaine
Bacteriophages are often used as surrogates for pathogenic human viruses in environmental studies to assess viral particle transport, survival, the efficiency of protective equipment, and disinfection treatments (Agranovski et al. 2005; Dee et al. 2005; Grinshpun, Adhikari, and Honda 2007; Li et al. 2009; Tseng and Li 2006). All surrogates have limits and can produce biases in risk assessment, but these phages have the advantage of being safe for humans and easy to handle in laboratories (Sinclair et al. 2012). In the present study, four tailless bacteriophages were used. MS2 (family of Leviridae, single-stranded RNA) and Phi6 (Cystoviridae, double-stranded RNA) were used as surrogates for RNA viruses, and PR772 (Tectiviridae, double-stranded DNA) and PhiX174 (Microviridae, single-stranded DNA) were used as surrogates for DNA viruses (Table 1). In addition, a strain of influenza A (H1N1) (Orthomyxoviridae, single-stranded RNA) was used as a model for a human virus.
Applications and hazards associated with carbon nanotubes in biomedical sciences
Published in Inorganic and Nano-Metal Chemistry, 2020
Ali Hassan, Afraz Saeed, Samia Afzal, Muhammad Shahid, Iram Amin, Muhammad Idrees
Another form of the gene that can be delivered effectively by use of CNTs is an aptamer. An aptamer is defined as a small single-stranded oligonucleotide that contain either DNA or RNA sequence. They are capable to find their intracellular target by looking for shape complementarity. Aptamers act as inhibitors for intracellular pathways because they possess the potential to disrupt protein-protein interactions.[72] Delivery of aptamers is a challenging factor for its role in gene therapy. This problem is solved by considering CNTs as vector system. Aptamers can be used as an anticancer agent against cancerous cells. Researchers utilized an RNA aptamer against epithelial cell adhesion molecule, a glycoprotein that is over-expressed in tumor cells and recently given the status of cancer marker. In this study, RNA aptamer was delivered through piperazine polyethyleneimine conjugated SWCNTs and investigated the activity of this delivery vector against up-regulated BCL 9 concerned with colorectal and breast cancer. The complex encouraged more cell death in MCF-7 cell line as a positive epithelial cell adhesion molecule as compared to the epithelial cell adhesion molecule negative cells. Through western blotting, a decreased level of BCL 9 protein was observed in MCF-7 that pointed out the targeting silencing.[73]