CRISPR/Cas12a-based photoelectrochemical sensing of microRNA on reduced graphene oxide-anchored Bi2WO6 coupling with catalytic hairpin assembly

Ultrasensitive CRISPR/Cas13a-Mediated Photoelectrochemical Biosensors for Specific and Direct Assay of miRNA-21

“…In recent years, the clustered regularly interspaced short palindromic repeats (CRISPR)/Cas systems containing CRISPR/Cas9, Cas12, Cas13, and Cas14 have been widely applied to biomedical research and clinical diagnostics. − Among these systems, Cas13a (previously known as C2c2) or Cas12a, as an RNA-guided ribonuclease, can be programmed with CRISPR RNAs (crRNAs) to nonspecifically cleave (termed trans -cleavage) nearby RNAs or DNAs, respectively, in the presence of its target RNA or DNA. − On average, this trans -cleavage activity activated by a single target nucleic acid can cleave numerous nonspecific nucleic acid strands at physiological temperature, resulting in signal amplification. − More importantly, compared to the previously reported signal amplification strategies including HCR, catalytic hairpin assembly, and DNA nanomachine, the CRISPR/Cas system can greatly simplify the operation difficulty and significantly improve the analytical performance of the biosensing platform without the need for complex nucleic acid sequence design and excessive experimental manipulations. Given these advantages, several CRISPR/Cas12a-assisted PEC biosensors have been developed for the sensitive detection of miRNAs. − Moreover, to further achieve a desired detection sensitivity, the CRISPR/Cas12a system was commonly integrated with nucleic acid pre-amplification for miRNA detection, such as polymerase chain reaction, rolling circle amplification, loop-mediated isothermal amplification, recombinase polymerase amplification, and so forth. − However, the integration strategies of the pre-amplification step and CRISPR assay are carried out in steps and usually involve the transfer of amplified products. It not only increases the detection time and operational complexity but also easily causes aerosol contamination.…”

ssDNA-Modified Gold Nanoparticles as a Tool to Detect miRNA Biomarkers in Osteoarthritis

“…Among the potential biological molecules, microRNAs (miRNAs or miRs) hold great promise as novel circulating biomarkers. miRNAs are small, single-stranded, noncoding RNAs composed of 22–28 nucleotides with a crucial role in post-transcriptional gene silencing. − They are encoded by miRNA genes or by introns located on genes, bind to complementary mRNAs, and inhibit their translation. , Besides functioning intracellularly, miRNAs can be transferred extracellularly by being packaged in membranous vesicles, such as exosomes, or bound to lipoproteins or other RNA-binding proteins . Until now, several studies have explored the role of miRNAs in OA, and about 80 of them have been associated with the underlying stage of the disease .…”

“…As proposed, miRNAs regulate the expression of both catabolic and anabolic genes and target different signaling pathways involved in the progression of the disease. The main biological functions that are regulated include chondrocyte proliferation and apoptosis, extracellular matrix synthesis, degradation, and inflammation. , …”

Sensitive Detection of Salmonella Based on CRISPR-Cas12a and the Tetrahedral DNA Nanostructure-Mediated Hyperbranched Hybridization Chain Reaction

“…A clustered regularly interspaced short palindromic repeat (CRISPR)-Cas system is a complex immune system in prokaryotes . In CRISPR-Cas12a systems, the Cas12a protein exhibits nonspecific collateral cleavage activity after activation by the target nucleic acid under the guidance of a guide-RNA (gRNA), , which is ingeniously employed for detection of nucleic acid-involving targets (e.g., miRNA, foodborne pathogens, HPV). ,− The merits of the CRISPR-Cas12a system are ultrahigh sensitivity, single-base specificity, and simplicity to operate due to the efficient degradation ability toward ssDNA reporters of the Cas12a. , Generally, to improve the sensitivity, the nucleic acid targets need to be amplified before activation of the CRISPR-Cas12a via some amplification techniques, such as PCR, loop-mediated isothermal amplification (LAMP), recombinase polymerase amplification (RPA), catalytic hairpin assembly (CHA), and recombinase-aided amplification (RAA) . When it involves foodborne pathogens, intricate sample pretreatment steps and DNA extraction are highly required, which possibly elongate the pretreatment process and the loss of target DNA. , As the development of immunomagnetic separation, whole bacterial detection becomes an interesting alternative in foodborne pathogen determination due to the simple sample pretreatment and circumvention of DNA extraction .…”