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MicroRNAs in Human Cancers and Therapeutic Applications
Published in Peixuan Guo, Kirill A. Afonin, RNA Nanotechnology and Therapeutics, 2022
Ji Young Yoo, Balveen Kaur, Tae Jin Lee, Peixuan Guo
Peptide nucleic acid (PNA) is a peptide bond-based nucleic acid mimic generated by replacing the sugar-phosphodiester backbone with N-(2-aminoethyl)-glycine units. The (2-aminoetyl)-glycine groups present no surface charge, which allows PNA molecules to pass through cell membranes by themselves. PNA is highly stable in serum and binds specifically to both DNA and RNA (Hanvey et al., 1992). PNA is shown to be highly stable in serum since PNA incubated for 2 hours in serum shows 100% structurally intact rate compared to only 8% for unmodified control peptides (Demidov et al., 1994). In a study where PNA-anti-miR-155 was given intraperitoneally to mice, endogenous miR-155 in primary B cells was successfully inhibited reducing the gene expression levels of PNA-treated mice to levels comparable to mir-155 deficient mice (Fabani et al., 2010). As LNA-based miRNA inhibitors are more cost-effective and have a higher cellular uptake, they are more popular to use than PNA.
Biomedical Applications II: Influence of Carbon Nanotubes in Cancer Therapy
Published in Giorgia Pastorin, carbon nanotubes, 2019
Fabbro Chiara, Toma Francesca Maria, Ros Tatiana Da
In 2005, Kerman et al reported an example of CNT-FETs on a silicon dioxide/silicon (SiO2/Si) substrate based on peptide nucleic acid (PNA) associated with tumour necrosis factor-a gene (TNF-a), for real-time electrical detection of DNA hybridisation with easy discrimination of singlenucleotide polymorphism.79 Tumour necrosis factor belongs to the cytokine family and is responsible for the inflammatory response and for some anomalies in the regulation process related to cancer (i.e., overexpression), and so it can be considered a biomarker for early cancer detection. PNA is a synthetic oligonucleotide, in which the phosphate and deoxyribose skeleton is replaced by a polypeptide, and it can hybridise with complementary DNA or RNA sequences. There are some advantages in using PNAs: their backbone is neutral and does not suffer from electrostatic repulsions, the base pairing is not influenced by ionic strength and they are not altered by proteases and nuclease degradation.
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Published in P. Dakin John, G. W. Brown Robert, Handbook of Optoelectronics, 2017
Constantinos Pitris, Tuan Vo-Dinh, R. Eugene Goodson, Susie E. Goodson
Nucleic acids have been widely used as bioreceptors for microarray and biochip systems [16, 17]. In DNA biochips, the biorecognition mechanism involves hybridization of DNA or RNA, which are the building blocks of genetics. The microarrays of probes on DNA biochips serve as reaction sites, each reaction site containing single strands of a specific sequence of a DNA fragment. These fragments can either be short oligonucleotide (about 18–24) sequences or longer strands of cDNA. The sequence of any known part of DNA (target) can be amplified by the polymerase chain reaction (PCR) and labeled with an optically detectable compound (e.g., a fluorescent label) inserted during the PCR process. When the targets contain more than one type of sample, each is labeled with a different tag so that they can be detected simultaneously. The complementarity of adenine:thymine (A:T) and cytosine:guanine (C:G) pairing in DNA provides the basis for the specificity of biorecognition in DNA biochips. When unknown fragments of single-strand DNA react (or hybridize) with the probes on the chip, double-strand DNA fragments form only when the target and the probe are complementary according to the base-pairing rule. Finally, the sample is tested for hybridization to the microarray by detecting the presence of the attached labels. Probes based on a synthetic biorecognition element, peptide nucleic acid (PNA), have also been developed [18]. PNA is an artificial oligo amide that is capable of binding very strongly to complementary oligonucleotide sequences.
Ultrasensitive electrocatalytic detection of COX-2 rs20417: relying on 3D interconnected architecture of Pt-LSSUs@PAA nanostructures for sensor interface modification
Published in Journal of Experimental Nanoscience, 2019
We use a multi-pronged strategy to minimise the current in the absence of target nucleic acid. The sensors are functionalised with aminated PNA probes complementary to the target sequence. PNA is a synthetic nucleic acid analogue that has a neutral charge. This neutral charge minimises the background current and increases the signal-to-noise ratio. Our assay employs Ru(NH3)63+ and [Fe(CN)6]3−/4−. The Ru(NH3)63+ electron acceptor complex is positively charged and binds to the sensors at levels that corresponding to the amount of negatively charged nucleic acid. In a potential sweep, adsorbed Ru(NH3)63+ is reduced at −200 mV, producing a measurable current that reports on the presence of the target DNA. However, the limited concentration of Ru(NH3)63+ localised at the bound target nucleic acids yields a small current. [Fe(CN)6]3− is introduced into the system to chemically oxidise the reduced Ru2+, which creates multiple redox cycles for a single Ru(NH3)63+ molecule and thus amplifies the observed current.