Catalytic hairpin assembly-assisted dual-signal amplification platform for ultrasensitive detection of tumor markers and intelligent diagnosis of gastric cancer

Instant synthesis of bimetallic CuCo PBA nanozyme for efficient colorimetric immunoassay of carcinoembryonic antigen

Colorimetric immunoassays are widely used for biomarker detection, offering advantages of simplicity, sensitivity, and cost-effectiveness. Recent advancements focus on improving the catalytic activity of nanozymes for enhancing the sensitivity and accuracy of such assays. Bimetallic CuCo Prussian blue analog (CuCo PBA) has emerged as promising candidates due to their excellent peroxidase-like activity. However, their instant synthesis and integration into immunoassays for the rapid detection of biomarkers like carcinoembryonic antigen (CEA) remain underexplored. This study presents an innovative approach using CuCo PBA nanozymes for colorimetric immunoassays with immediate generation and application. In this study, CuCo PBA nanozymes were synthesized instantly by reacting Cu2+ with K3[Co(CN)6] (<1 min), and their peroxidase-like activity was exploited for a colorimetric immunoassay system targeting CEA. The system demonstrated a clear blue color change upon the reaction of CuCo PBA with H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB), enabling sensitive detection. The assay was optimized for various parameters, including pH, temperature, and material ratio. A linear response was obtained for CEA detection over a concentration range of 0.05-60 ng/mL with a limit of detection (LOD) of 22 pg/mL. The integration of glucose oxidase (GOx) mediated the generation of H2O2, triggering the colorimetric reaction. This instantaneous CuCo PBA-based system effectively detected CEA in human serum samples, highlighting its potential for rapid diagnostic applications. This work introduces a novel approach for rapid and sensitive colorimetric immunoassays using CuCo PBA nanozymes that are synthesized on-demand and immediately applied. The system allows for efficient CEA detection with an exceptionally low detection limit, offering great potential for clinical diagnostics. The instant generation and application of CuCo PBA nanozymes in immunoassays represent a significant advancement in point-of-care testing technologies.

A ratio luminescent europium organometallic gel for in vitro detection of hepatocellular carcinoma marker and cellular imaging

Hepatocellular carcinoma is a particularly aggressive form of liver malignancy, representing one of the most formidable threats to human health and a major contributor to cancer-related deaths. Cholyglycine (CG), which plays a pivotal role in lipid metabolism, has garnered attention as a potential biomarker for hepatocellular carcinoma. Nevertheless, the structural resemblance of CG to various bile acids complicates the specific identification of CG. Therefore, the effective monitoring of CG in biological samples is still a challenge to be solved. In this study, a europium-based metal organic gel (Eu-MOG) with dual emission was synthesized and displayed an obvious luminescent color change from red to blue for CG. The synthesized Eu-MOG exhibits excellent selectivity towards CG, and enables the sensitive detection of CG in serum with LOD as 307 ppb. This character of Eu-MOG has also been validated in cell imaging for CG, which make this europium-based probe sufficient for clinical monitoring of CG to diagnosis hepatocellular carcinoma. The results of our experiments, corroborated by theoretical calculations, indicate that the high sensitivity of MOG to CG stems from the intermolecular N-H⋯O interaction between CG and the ligand H2NDC. This interaction facilitates intermolecular charge transfer, which in turn alters the luminescence of the europium-based metal-organic gel (Eu-MOG). This study provides a robust platform for the early diagnosis of hepatocellular carcinoma and contributes significantly to the evaluation of human hepatobiliary metabolic status.

T4 DNA Polymerase-Proofread DNA Binding Identifier for Sensitive Homogeneous Immunoassays

Aptamer-based homogeneous immunoassays exhibit considerable potential in the domains of bioanalysis and biodiagnosis owing to their universality in analyzing both proteins and small molecules as well as their compatibility with nucleic acid amplification technologies. Nevertheless, the substantial signal leakage by nonspecific aptamer allostery poses a challenge to enhancing sensitivity further. Herein, we reported a T4 DNA polymerase-proofread DNA binding identifier (ReID). This strategy could harness the dual-enzymatic activity of T4 DNA polymerase to eliminate the leaked signal, thereby efficiently integrating target-induced aptamer allostery with subsequent polymerase chain reaction signal amplification. Moreover, we explored the regulation mechanism of dNTPs concentration on the dual-enzymatic activity of the T4 DNA polymerase. As a result, this strategy achieved an ultrasensitive protein detection limit of 8 fg/mL, validating the effectiveness of this proofreading approach. The universality was further confirmed by highly sensitive detection of small molecules. The exploration of ReID represents a significant advancement in the sensitivity and universality of immunoassays, even demonstrating the potential for multiple proteomic assays, offering a novel perspective for the development of high-performance homogeneous immunoassays.

Integrating CRISPR-Cas12a with Aptamer as a Logic Gate Biosensing Platform for the Detection of CD33 and CD123

Molecular logic gates, as biomolecule-based computational systems, are highly suitable for multitarget detection due to their programmability and modularity. However, existing systems are primarily limited to nucleic acid detection and have not been widely applied to disease-related sensing, particularly for disease antigens. CD33 and CD123 are critical biomarkers for acute myeloid leukemia (AML), yet conventional detection methods rely on expensive equipment and complex procedures, limiting their accessibility and practicality. This study designs a DNA logic gate system integrating nucleic acid aptamers, catalytic hairpin assembly (CHA), and CRISPR-Cas12a, pioneering its use for AML antigen detection. The system comprises three modules: input recognition, signal amplification, and signal transduction. Nucleic acid aptamers specifically identify CD33 and CD123, while CHA enables efficient signal amplification and CRISPR-Cas12a generates a fluorescent output via trans-cleavage activity. The system operates stably at room temperature and implements multiple logic gate models, including YES, OR, AND, NOR, and INHIBIT, enabling the simultaneous detection of CD33 and CD123. Experimental results are visually distinguishable under blue light, and the system requires only standard fluorescence detection instruments. In serum samples, it exhibits excellent selectivity and stability, with a detection limit of 0.5 ng/mL. This study pioneers the application of logic gate technology for disease antigen detection, addressing a critical gap in AML biomarker sensing. Our study indicates that this logic detection platform, characterized by its simplicity in operation, high sensitivity, and versatility in logic functions, holds promise as a potent sensing system for the intelligent multiplex target detection of disease antigens, environmental pollutants, and heavy metals.

Structure-switching G-quadruplex: An efficient CRISPR/Cas12a signal reporter for label-free colorimetric biosensing

G-quadruplex is widely used as a signal reporter for colorimetric biosensor construction. However, the effectiveness of CRISPR/Cas12a in trans-cleaving G-quadruplexes is significantly influenced by their resistance to nuclease, resulting in a weak colorimetric signal response. Herein, a structure-switching G-quadruplex regulated by transducer DNA is used as a signal reporter to construct CRISPR/Cas12a-based biosensors. The transducer DNA lacks a stable secondary structure, enabling efficient cleavage by CRISPR/Cas12a, which subsequently affects the catalytic activity of the G-quadruplex/hemin DNAzyme. We used microRNAs (miRNAs) and ATP as model targets to develop a label-free colorimetric detection platform. By optimizing the DNA sequences and reaction conditions, the biosensors exhibit excellent detection selectivity and sensitivity. The reliability of the proposed method was validated by its consistency with RT-qPCR for miRNAs detection and a commercial chemiluminescence kit for ATP assay, demonstrating its potential in clinical diagnosis and bioanalytical studies. The assay is concise and cost-effective because it does not require DNA labeling, magnetic separation, or enzymatic DNA amplification. Our design strategy avoids the use of G-quadruplex as a cleavage substrate for CRISPR/Cas12a while ensuring an efficient response of the G-quadruplex/hemin DNAzyme to CRISPR/Cas12a system, addressing the issue of G-quadruplex resistance to CRISPR/Cas12a nuclease activity.

A sensitive miRNA detection method based on a split-T7 switch modulating CRISPR/Cas12a system

This study presents a novel method for sensitive miRNA detection based on a split-T7 switch modulating CRISPR/Cas12a system. By integrating the split-T7 promoter-mediated transcription with the CRISPR/Cas12a system, this method can achieve femtomolar detection of the target miRNA within 1 h and successfully analyze miR-21 in samples from various cell lines, demonstrating its potential for clinical applications.

CRISPR/Cas detection with nanodevices: moving deeper into liquid biopsy

The emerging field of liquid biopsy has garnered significant interest in precision diagnostics, offering a non-invasive and repetitive method for analyzing bodily fluids to procure real-time diagnostic data. The precision and accuracy offered by the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (CRISPR/Cas) technology have advanced and broadened the applications of liquid biopsy. Significantly, when combined with swiftly advancing nanotechnology, CRISPR/Cas-mediated nanodevices show vast potential in precise liquid biopsy applications. However, persistent challenges are still associated with off-target effects, and the current platforms also constrain the performance of the assays. In this review, we highlight the merits of CRISPR/Cas systems in liquid biopsy, tracing the development of CRISPR/Cas systems and their current applications in disease diagnosis particularly in liquid biopsies. We also outline ongoing efforts to design nanoscale devices with improved sensing and readout capabilities, aiming to enhance the performance of CRISPR/Cas detectors in liquid biopsy. Finally, we identify the critical obstacles hindering the widespread adoption of CRISPR/Cas liquid biopsy and explore potential solutions. This feature article presents a comprehensive overview of CRISPR/Cas-mediated liquid biopsies, emphasizing the progress in integrating nanodevices to improve specificity and sensitivity. It also sheds light on future research directions in employing nanodevices for CRISPR/Cas-based liquid biopsies in the realm of precision medicine.