Isolation of target DNA using synergistic magnetic bead transport and electrokinetic flow

2021 ◽  
Vol 15 (2) ◽  
pp. 024104
Author(s):  
Lindsay Schneider ◽  
Francis Cui ◽  
Anubhav Tripathi
Micromachines ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1204
Author(s):  
Zackary A. Zimmers ◽  
Alexander D. Boyd ◽  
Hannah E. Stepp ◽  
Nicholas M. Adams ◽  
Frederick R. Haselton

Among nucleic acid diagnostic strategies, non-enzymatic tests are the most promising for application at the point of care in low-resource settings. They remain relatively under-utilized, however, due to inadequate sensitivity. Inspired by a recent demonstration of a highly-sensitive dumbbell DNA amplification strategy, we developed an automated, self-contained assay for detection of target DNA. In this new diagnostic platform, called the automated Pi-powered looping oligonucleotide transporter, magnetic beads capture the target DNA and are then loaded into a microfluidic reaction cassette along with the other reaction solutions. A stepper motor controls the motion of the cassette relative to an external magnetic field, which moves the magnetic beads through the reaction solutions automatically. Real-time fluorescence is used to measure the accumulation of dumbbells on the magnetic bead surface. Left-handed DNA dumbbells produce a distinct signal which reflects the level of non-specific amplification, acting as an internal control. The autoPiLOT assay detected as little as 5 fM target DNA, and was also successfully applied to the detection of S. mansoni DNA. The autoPiLOT design is a novel step forward in the development of a sensitive, user-friendly, low-resource, non-enzymatic diagnostic test.


Equipment ◽  
2006 ◽  
Author(s):  
C. Yang ◽  
G. Y. Tang ◽  
D. G. Yan ◽  
H. Q. Gong ◽  
John C. Chai ◽  
...  

Author(s):  
S.N Mbugua ◽  
L.W Njenga ◽  
R.A Odhiambo ◽  
S.O Wandiga ◽  
M.O Onani

: Modern anticancer drugs target DNA specifically on rapid division of malignant cells. One downside of this approach is that they also target other rapidly dividing healthy cells such as those involved in hair growth leading to serious toxic side effects and hair loss. Therefore, it would be better to develop novel agents that address cellular signalling mechanisms unique to cancerous cells, and new research is now focussing on such approaches. Although the classical chemotherapy area involving DNA as the set target continues to produce important findings, nevertheless, a distinctly discernible emerging trend is the divergence from the cisplatin operation model that uses the metal as the primary active centre of the drug. Many successful anti-cancer drugs present are associated with elevated toxicity levels. Cancers also develop immunity against most therapies and the area of cancer research can therefore be seen as an area with a high unaddressed need. Hence, ongoing work into cancer pathogenesis is important to create accurate preclinical tests which can contribute to the development of innovative drugs to manage and treat cancer. Some of the emergent frontiers utilizing different approaches include nanoparticles delivery, use of quantum dots, metal complexes, tumour ablation, magnetic hypothermia and hyperthermia by use of Superparamagnetic Iron oxide Nanostructures, pathomics and radiomics, laser surgery and exosomes. This review summarizes these new approaches in good detail giving critical views with necessary comparisons. It also delves into what they carry for the future including their advantages and disadvantages.


ACS Sensors ◽  
2021 ◽  
Author(s):  
Luciano F. Huergo ◽  
Khaled A. Selim ◽  
Marcelo S. Conzentino ◽  
Edileusa C. M. Gerhardt ◽  
Adrian R. S. Santos ◽  
...  

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Bo Zhang ◽  
Diyin Luo ◽  
Yu Li ◽  
Vanja Perčulija ◽  
Jing Chen ◽  
...  

AbstractCas12i is a newly identified member of the functionally diverse type V CRISPR-Cas effectors. Although Cas12i has the potential to serve as genome-editing tool, its structural and functional characteristics need to be investigated in more detail before effective application. Here we report the crystal structures of the Cas12i1 R-loop complexes before and after target DNA cleavage to elucidate the mechanisms underlying target DNA duplex unwinding, R-loop formation and cis cleavage. The structure of the R-loop complex after target DNA cleavage also provides information regarding trans cleavage. Besides, we report a crystal structure of the Cas12i1 binary complex interacting with a pseudo target oligonucleotide, which mimics target interrogation. Upon target DNA duplex binding, the Cas12i1 PAM-interacting cleft undergoes a remarkable open-to-closed adjustment. Notably, a zipper motif in the Helical-I domain facilitates unzipping of the target DNA duplex. Formation of the 19-bp crRNA-target DNA strand heteroduplex in the R-loop complexes triggers a conformational rearrangement and unleashes the DNase activity. This study provides valuable insights for developing Cas12i1 into a reliable genome-editing tool.


Biomolecules ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1162
Author(s):  
Seohyun Kim ◽  
Sangmin Ji ◽  
Hye Ran Koh

Clustered regularly interspaced short palindromic repeats (CRISPR)-Cas system has recently gained growing attention as a diagnostic tool due to its capability of specific gene targeting. It consists of Cas enzymes and a guide RNA (gRNA) that can cleave the target DNA or RNA based on the sequence of the gRNA, making it an attractive genetic engineering technique. In addition to the target-specific binding and cleavage, the trans-cleavage activity was reported for some Cas proteins, including Cas12a and Cas13a, which is to cleave the surrounding single-stranded DNA or RNA upon the target binding of Cas-gRNA complex. All these activities of the CRISPR-Cas system are based on its target-specific binding, making it applied to develop diagnostic methods by detecting the disease-related gene as well as microRNAs and the genetic variations such as single nucleotide polymorphism and DNA methylation. Moreover, it can be applied to detect the non-nucleic acids target such as proteins. In this review, we cover the various CRISPR-based diagnostic methods by focusing on the activity of the CRISPR-Cas system and the form of the target. The CRISPR-based diagnostic methods without target amplification are also introduced briefly.


Author(s):  
Daisuke Miki ◽  
Rui Wang ◽  
Jing Li ◽  
Dali Kong ◽  
Lei Zhang ◽  
...  

Abstract Humans are currently facing the problem of how to ensure that there is enough food to feed all of the world’s population. Ensuring that the food supply is sufficient will likely require the modification of crop genomes to improve their agronomic traits. The development of engineered sequence-specific nucleases (SSNs) paved the way for targeted gene editing in organisms, including plants. SSNs generate a double-strand break (DSB) at the target DNA site in a sequence-specific manner. These DSBs are predominantly repaired via error-prone non-homologous end joining (NHEJ), and are only rarely repaired via error-free homology-directed repair (HDR) if an appropriate donor template is provided. Gene targeting (GT), i.e., the integration or replacement of a particular sequence, can be achieved with combinations of SSNs and repair donor templates. Although its efficiency is extremely low, GT has been achieved in some higher plants. Here, we provide an overview of SSN-facilitated GT in higher plants and discuss the potential of GT as a powerful tool for generating crop plants with desirable features.


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