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The Emerging Field of RNA Nanotechnology
Published in Lajos P. Balogh, Nano-Enabled Medical Applications, 2020
A striking marvel demonstrating the addressable and programmable property of DNA is Rothemund’s DNA origami [60], where a long single-stranded viral DNA is used as a scaffold for binding shorter strands to generate well-defined 2D and 3D configurations. DNA origami was subsequently applied to build 3D boxes that can be locked and unlocked [61], nanoarrays for label-free detection of substrates [62] and for structure elucidation of organized proteins [63]. Rationally designed supramolecular DNA assemblies can be conjugated with organic and inorganic molecules, such as conjugation of porphyrins on parallel DNA helix bundles [64] nanomagnets [65] and elegant nanomachines [58, 66]. Replicable DNA architectures have been achieved to scale-up DNA nanostructure production for practical applications by using enzymatic rolling circle replication, bacterial cells infected with a viral vector [67], or chemical approaches for amplifying branched DNA arms [68].
Maternal plasma cell-free DNA screening
Published in Moshe Hod, Vincenzo Berghella, Mary E. D'Alton, Gian Carlo Di Renzo, Eduard Gratacós, Vassilios Fanos, New Technologies and Perinatal Medicine, 2019
There are other methods that are in clinical use in some countries, but these generally are based on more limited validation studies or scant published data on clinical experience. One is based on quantitative PCR of specific target sequences (27). Another relies on incorporation of target regions into circular DNA that can undergo rolling circle replication, fluorophore labeling of the products, and detection following nanoparticle filtration (28). It is reasonable to anticipate that other approaches to cfDNA screening will emerge. While all methods appear to show high detection rates and low false-positive rates for Down syndrome, it should not be assumed that they are all equivalent.
Human Bocavirus
Published in Dongyou Liu, Handbook of Foodborne Diseases, 2018
José Luiz Proença-Módena, Guilherme Paier Milanez, Eurico Arruda
In the “rolling-hairpin” model, hairpin structures flanking the viral genome are used as primers for the initiation of DNA replication, generating DNA concatemers, which may be present in two possible intermediate structures: head-to-head and tail-to-tail. In studies assessing primary airway epithelial cells, it was possible to verify the formation of head-to-head structures. However, to date, these structures have not been observed in vivo, supporting the hypothesis that HBoV replicates using an alternative mechanism, supposedly by helper virus-dependent initiation in a rolling-circle replication model.
Focus on the frontier issue: progress in noninvasive prenatal screening for fetal trisomy from clinical perspectives
Published in Critical Reviews in Clinical Laboratory Sciences, 2023
Meng Tian, Lei Feng, Jinming Li, Rui Zhang
Despite the ACOG endorsement, NGS-based NIPS has not been utilized globally due to the inherent limitations in sequencing methods. First, due to the nature of cffDNA in maternal circulation and the high maternal DNA background, it is difficult to detect small amounts of cffDNA present in samples [28]. Second, the need for exclusive equipment and technical expertise limits the routine use of sequencers in basic diagnostic laboratories. Third, a long turnaround time (approximately 10 days) is not ideal in clinical practice [29]. The high cost and complexity of existing sequencing methods further hinder the utility of NIPS for pregnant women. Many amplification methods have been developed with the aim of overcoming the limitations of sequencing methods. These include rolling circle replication (RCR) and peptide nucleic acid (PNA) probe-based real-time polymerase chain reaction (RT-PCR).
Biomaterials-assisted construction of neoantigen vaccines for personalized cancer immunotherapy
Published in Expert Opinion on Drug Delivery, 2023
It has also been found that the abnormal activation of immunosuppressive signal transduction pathways inside APCs represents as another biological barriers hindering the vaccination efficacy of various cancer vaccines [70,71]. To remove the negative role of STAT3, a member of the Janus kinase-signal transducer and activator of transcription (STAT) family, on the CpG promoted activation of APCs, a recent study reported the synthesis of a biostable intertwining DNA-RNA nano-capsules (iDR-NCs) of CpG and Stat3 short hairpin RNA through the combined rolling circle replication (RCR) and rolling circle transcription (RCT) reactions (Figure 2a-f) [49]. After being condensed with cationic PEG-grafted polypeptides and loaded with neoantigens, the yielded nanovaccines would enable sustained presentation of neoantigens to elicit more potent specific peripheral CD8+ T cell response than that with free CpG as the immunostimulatory adjuvant. As a result, such nanovaccines could effectively suppress the growth of these neoantigen-specific colorectal tumors in mice, highlighting them as a promising candidate for effective personalized cancer immunotherapy.
The current and future applications of in situ hybridization technologies in anatomical pathology
Published in Expert Review of Molecular Diagnostics, 2022
Hoi Yi Leung, Martin Ho Yin Yeung, Wai Tung Leung, King Hin Wong, Wai Yan Tang, William Chi Shing Cho, Heong Ting Wong, Hin Fung Tsang, Yin Kwan Evelyn Wong, Xiao Meng Pei, Hennie Yuk Lin Cheng, Amanda Kit Ching Chan, Sze Chuen Cesar Wong
A localized signal is generated by the isothermal amplification of the oligonucleotide circle. As the polymerase progresses along the probe, the 60 bases on the probe are amplified thousands of times. Incorporating a labeled nucleotide during the rolling circle replication (RCA) reaction produces sufficient signal for easy visualization of the target. In one single round of enzymatic amplification, RCA significantly increases signal and sensitivity, making it much simpler and robust than other signal amplification techniques, such as CARD and branched ISH that requires multi-step amplification. Furthermore, RCA amplification is done isothermally, which allows better preservation of tissue morphology [33,35].