A controllable CRISPR/Cas12a-based signal logic gate that enables simultaneous detection of KRAS G12C mutation and Septin9 promoter methylation in a single reaction and offers a simple and reliable platform for simultaneous genetic and epigenetic analysis in point-of-care cancer screening.
Abstract
Early detection of both genetic mutations and epigenetic modifications is critical for cancer diagnosis, but current methods often require separate assays or suffer from bisulfite-induced DNA damage. Here, we present a controllable CRISPR/Cas12a-based signal logic gate that enables simultaneous detection of KRAS G12C mutation and Septin9 promoter methylation in a single reaction. The strategy converts target information into two distinct ssDNA activators (T1 for methylation and T2 for mutation) via orthogonal enzymatic cascades (GlaI- and FEN1-mediated cleavage followed by strand displacement amplification). By limiting crRNA concentrations, the CRISPR/Cas12a trans-cleavage activity produces three well-resolved fluorescence kinetic states: low (mutation only), medium (methylation only), and high (both targets), respectively, which could be distinguished using three predefined threshold values. Validation with clinical samples from colorectal cancer patients and healthy controls showed complete concordance with Sanger sequencing and qPCR. And the proposed method successfully detected Septin9 methylation in peripheral blood. This isothermal, single-tube, bisulfite-free strategy offers a simple and reliable platform for simultaneous genetic and epigenetic analysis in point-of-care cancer screening.
A previously unrecognized feature of CRISPR/Cas12a is identified, in which incorporation of ribonucleotides into single stranded DNA targets modulates Cas12a activation efficiency, revealing a hybrid DNA/RNA-dependent regulation of Cas12a activity.
Xiang-Lan He, Le Wang, Cong Zhang et al.· bioRxiv· 0 citations
DNA methylation is an important epigenetic biomarker for early disease screening and prognosis evaluation, but its reliable detection remains challenging because methylated DNA is often present at low abundance in complex biological backgrounds. Here, we report a methylation-sensitive bioelectronic sensing platform that integrates AciI-assisted target discrimination, CRISPR/Cas12a-mediated trans-cleavage, and vertical organic electrochemical transistors (vOECTs) amplification for highly sensitive methylated DNA detection. In this strategy, unmethylated DNA is selectively digested by AciI, while intact methylated DNA activates the crRNA-guided Cas12a system, triggering collateral cleavage of ssDNA reporters immobilized on the Au gate electrode. The resulting interfacial changes are efficiently amplified by the vOECTs through coupled electric-double-layer gating. The platform achieved quantitative methylated DNA detection from 100 fM to 100 pM with a sensitivity of 267.6 μA/dec and a detection limit of 100 fM. The sensor also exhibited good operational stability, reproducibility, and reliable recovery performance in artificial serum samples. This work demonstrates the potential of CRISPR/vOECTs bioelectronics for sensitive epigenetic analysis and presents a promising proof-of-concept for future non-invasive screening strategies.
Kun Xu, Sibo Wang, Kejie Zhang et al.· Talanta: The International J...· 0 citations
MicroRNAs (miRs) are central regulators of tumor initiation and progression, and their aberrant expression patterns have been identified as clinically valuable biomarkers for the early diagnosis of malignancies and prognostic evaluation. Here, we report tag-free fluorescence biosensing platform for the detection of circulating miRs in serum, targeting microRNA-21 (miR-21) and microRNA-10b (miR-10b) as clinically relevant oncogenic markers. The assay integrates CRISPR/Cas12a-mediated signal regulation with complementary strand (CS)-mediated target recognition. In this strategy, target miRs hybridize with the CS, thereby preventing CS-mediated activation of the Cas12a-crRNA complex. As a result, Cas12a collateral cleavage is suppressed, the G-quadruplex reporter remains intact, and Thioflavin T fluorescence is enhanced. The platform demonstrated excellent sequence discrimination capability, effectively distinguishing closely related and mismatched targets. Sensitive quantification was achieved with limits of detection of 1.4 nM for miR-21 and 852 pM for miR-10b. Importantly, robust analytical performance was maintained in complex biological matrices, confirming its applicability to serum samples. Collectively, this CRISPR/Cas12a-enabled fluorescent biosensor provides a simple approach for circulating miR detection.
Sepideh Hassibian, Masoomeh Esmaelpourfarkhani, M. Alibolandi et al.· Methods· 0 citations
A novel triple-modal biosensor integrating hybridization chain reaction (HCR) with CRISPR/Cas12a was developed for sensitive and selective detection of kanamycin (KANA) and bisphenol A (BPA). The system employs a phosphorothioate-modified G-rich hairpin (SHG4-2) as a dual-functional reporter probe, which resists Cas12a trans-cleavage and enables multimodal signal output via SG-quadruplex (SG4) formation. Upon target recognition by aptamers, an initiator strand is released to trigger HCR amplification, generating long double-stranded DNA products that activate Cas12a trans-cleavage. This cleaves the (SHG4-2) probe, releasing SG-rich sequences that self-assemble into SG4 structures, yielding fluorescence (with Thioflavin T), colorimetric (via SG4/hemin-catalyzed TMB oxidation), and smartphone-readable RGB signals. This platform enables parallel detection of a single target analyte, allowing flexible detection modes. Under optimized conditions, the sensor achieved detection limits as low as 20.1 pM for KANA and 6.8 pM for BPA in fluorescence mode, 32.3 pM for KANA and 17.1 pM for BPA in colorimetric mode, and 74.3 pM for KANA and 35.8 pM for BPA in smartphone mode, with excellent selectivity against interfering analogues. Successful application in spiked milk samples demonstrated high recovery rates and good reproducibility. In addition, the platform supports the logical gate operations of OR (single-target detection) and AND (dual-target detection), which allows flexible detection modes. This work presents a versatile, amplification-enhanced multimodal sensing strategy for environmental and food safety monitoring, highlighting its potential for logic-driven biosensing applications.
Xiaolong Li, Daxiu Li, Yanni Wang et al.· Analytical Methods· 0 citations
On-site nucleic acid detection plays a crucial role in disease diagnosis, biosafety monitoring, and food quality control. This study develops a novel nucleic acid detection platform that integrates catalytic hairpin assembly (CHA) with the CRISPR/Cas12a system and utilizes pregnancy test strips (PTS) for result visualization, addressing the limitations of existing nucleic acid detection methods in balancing sensitivity, specificity, and portability with cost and dependence on a cleanroom. The main mechanism involves the following three steps. The presence of target RNA triggers the CHA reaction, generating double-stranded DNA (dsDNA) as an activation unit. Subsequently, this unit activates the CRISPR/Cas12a system to specifically cleave the single-stranded DNA (ssDNA) that has bridged human chorionic gonadotropin (HCG) to a magnetic bead, ultimately releasing HCG that produces a visual result on the PTS. This dual-signal amplification strategy (CHA cycling and Cas12a trans-cleavage) can detect concentrations as low as 10 pM in approximately 50 min, without the need for pre-amplification of the target nucleic acid. This detection system ensures high sensitivity and specificity while effectively avoiding non-specific activation. In practical applications with transgenic maize samples, the detection results are highly consistent with those of real-time quantitative polymerase chain reaction (qPCR), validating its reliability in real-world scenarios. This innovative method offers advantages such as simple operation and low cost, providing an efficient tool for rapid nucleic acid detection while demonstrating broad potential for application in resource-limited settings.
Huimin Wang, Lin Liu, Chengxin Bao et al.· Lab on a Chip· 0 citations
A one-pot self-primer isothermal exponential amplification reaction (SP-EXPAR) combined with a CRISPR/Cas14a assay was developed for detecting KRAS G12C and G12D and demonstrated 100% sensitivity and 100% specificity compared with DNA sequencing.
Guozhi Yang, Yaqin Chen, Wenyong Zhao et al.· Analytical Methods· 0 citations
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