DNAzyme-based colorimetric assay and its application for lipopolysaccharide analysis assisted by oxime chemistry

A Point-of-Care Aptasensor for the Real-Time Detection of Sepsis Biomarker

The rising demand for noninvasive portable point-of-care (POC) sensors for on-site detection of biomarkers reflects a shift toward personalized healthcare and real-time diagnostics. Lipopolysaccharide (LPS) is a key sepsis biomarker, a bacteria-borne endotoxin that can induce fatal conditions, such as septic shock, if left undetected. Timely bedside detection of LPS is critical for the appropriate intervention and treatment of sepsis. In this work, we report a highly sensitive electrochemical sensor chip designed for the selective detection of LPS, which is compatible with a portable analyzer for on-site detection. The sensor is fabricated using functionalized CNT (fCNT) and copper(I) oxide nanoparticles (Cu2O). Functionalized with the LPS-specific aptamer, the sensor demonstrated remarkable selectivity and sensitivity toward LPS. It achieved a limit of detection (LOD) of 10 ag mL-1 and exhibited a linear detection range from 10 ag mL-1 to 10 ng mL-1. The device detected LPS across various samples, including food samples such as mayonnaise and fruit juices, as well as a clinical sample, whole blood. These results underscore its potential for practical application in food quality assurance and clinical diagnostics, offering real-time analysis capabilities.

Electrochemical DNAzyme-based biosensors for disease diagnosis

DNAzyme-based electrochemical biosensors provide exceptional analytical sensitivity and high target recognition specificity for disease diagnosis. This review provides a critical perspective on the fundamental and applied impact of incorporating DNAzymes in the field of electrochemical biosensing. Specifically, we highlight recent advances in creating DNAzyme-based electrochemical biosensors for diagnosing infectious diseases, cancer and regulatory diseases. We also develop an understanding of challenges around translating the research in the field of DNAzyme-based electrochemical biosensors from labs to clinics, followed by a discussion on different strategies that can be applied to enhance the performance of the currently existing technologies to create truly point-of-care electrochemical DNAzyme biosensors.

A Multicomponent Nucleic Acid Enzyme-Cleavable Quantum Dot Nanobeacon for Highly Sensitive Diagnosis of Tuberculosis with the Naked Eye

Clinical tuberculosis (TB) screening and diagnosis are crucial for controlling the spread of this life-threatening infectious disease. In this work, a novel, rapid, and simple colorimetric detection platform for TB was developed based on a quantum dot-based nanobeacon (QD-NB) and multicomponent nucleic acid enzyme (MNAzyme). In the presence of target DNA (IS1081 gene fragment), the recombinase polymerase amplification (RPA) was performed and the amplicons were chemically DNA-denatured and then subjected to MNAzyme reaction. RNA-cleaving MNAzyme assembly included the recognition of target DNA and hybridization with a QD-NB fluorescence probe. Under the addition of Mg²⁺, the RNA-containing QD-NB as a cleavable substrate could be broken into two DNA fragments, leading to green fluorescence release due to their departure from a black hole quencher (BHQ2). The TB detection could be achieved with the naked eye under a portable and inexpensive UV flashlight. Our results demonstrated that QD-NB-based MNAzyme colorimetric assays improved the detection sensitivity by 1 order of magnitude compared with the detection using RPA. The limit of detection (LOD) of the visual reading was as low as 2 copies/μL (3.3 amol/L). Excellent specificity and reproducibility could also be achieved. Furthermore, the practical application of the colorimetric method for TB diagnosis was verified by 36 clinical TB patients and 20 healthy individuals. The developed QD-NB-based MNAzyme colorimetric assays provided a rapid, convenient, sensitive, and accurate alternative for clinical TB screening and diagnosis.

Recent Advances on Functional Nucleic-Acid Biosensors

In the past few decades, biosensors have been gradually developed for the rapid detection and monitoring of human diseases. Recently, functional nucleic-acid (FNA) biosensors have attracted the attention of scholars due to a series of advantages such as high stability and strong specificity, as well as the significant progress they have made in terms of biomedical applications. However, there are few reports that systematically and comprehensively summarize its working principles, classification and application. In this review, we primarily introduce functional modes of biosensors that combine functional nucleic acids with different signal output modes. In addition, the mechanisms of action of several media of the FNA biosensor are introduced. Finally, the practical application and existing problems of FNA sensors are discussed, and the future development directions and application prospects of functional nucleic acid sensors are prospected.