A signal conversion system using binding-induced strand displacement for disease biomarker assay

Mass Spectrometric Multiplex Detection of MicroRNA and Protein Biomarkers for Liver Cancer

The occurrence of cancers is often accompanied by the abnormal expression of several sorts of biomarkers (e.g., nucleic acids and proteins). The multiplex assessment of them would substantially aid in the early detection and precise diagnosis, which is often hampered by their different detection schemes, different reaction matrix and reagents, and spectral overlapping. Herein, we propose a simple and sensitive mass spectrometric method for the multiplex detection of nucleic acid and protein, in which liver cancer-related biomarkers miRNA 223 and alpha-fetoprotein (AFP) were selected as model analytes. The self-amplification effect of metal atom-based nanoparticle probes can provide high sensitivity in complex serum samples without any additional amplification procedure. The detection limits for the simultaneous detection of miRNA 223 and AFP were 103 (2.1 pM) and 219 amol (0.15 ng/mL), respectively, with high specificity and selectivity. The proposed method is potentially useful for the rapid screening of cancers.

Dual-amplified CRISPR-Cas12a bioassay for HIV-related nucleic acids

Nucleic acid amplification strategies have successfully dominated ultrasensitive bioassays, but they sometimes bring high time-consumption, multi-step operation, increased contamination risk, and mismatch-related inaccuracy. We proposed a nucleic acid amplification-free method called the AuNPs-tagging based CRISPR-Cas12a bioassay platform. The signal amplification was realized by integrating the self-amplification effect of CRISPR-Cas12a with the enhancement effect of the large number of detectable atoms inside each gold nanoparticle. The proposed method achieved a low LOD of 1.05 amol in 40 min for HIV-related DNA.

Multiplex DNA Walking Machines for Lung Cancer-Associated miRNAs

Biomimetic DNA walking machines have gained great success in scrutinizing the microscopic world and sensitive biosensing of disease biomarkers. Despite superb achievements, the research on DNA walking machines for simultaneous detection of multiple analytes is still rare, while the design and realization of multiplexing are considered as an important bottleneck. The multiplex detection of biomarkers can not only improve the specificity of bioassays but also avoid the squander of valuable biological specimens. Herein, we reported multiplex three-dimensional (3D) DNA walking machines based on high-resolution inductively coupled plasma mass spectrometry (HR-ICPMS) for lung cancer-associated miRNA detection. In the presence of lung cancer-associated target miRNAs (miR-21, miR-141, and miR-125b), DNA walking machines were stimulated and operated to liberate a large number of lanthanide elements (Tb, Ho, and Tm), and then the signals were collected simultaneously by HR-ICPMS. The recovery test of target miRNAs in human serum and the simultaneous monitoring experiment of three miRNAs in human lung cancer cell line (A549) and normal cell line (HBE) specimens display satisfactory analysis capabilities for complex biological samples. Thanks to the vast potential of lanthanide tags and the modular design, the proposed bioassay might flexibly detect different miRNA combinations with corresponding sets of DNA walking machines to meet the requirements of various tasks.

HOGG1-assisted DNA methylation analysis via a sensitive lanthanide labelling strategy

The assessment of DNA methylation level is an important indicator for the diagnosis and treatment of some diseases. DNA methylation assays are usually based on nucleic acid amplification strategies, which are time-consuming and complicated in operation procedures. Herein, we proposed a sensitive lanthanide-labelled ICP-MS method for DNA methylation analysis that exploited the feature of Human 8-oxoGuanine DNA Glycosylase (hOGG1), which specifically recognizes 8-oxo-G/5mC base pairs to effectively distinguish methylated DNA. A low limit of detection of 84 pM was achieved, and a 0.1% methylation level can be discriminated in the mixture, without any amplification procedure. Compared with commonly used nucleic acid amplification strategies, this proposed method is time-saving and low probability of false positive. Moreover, this work has been successfully validated in human serum samples, the recovery rates is between 96.7% and 105%, and the relative standard deviation (RSD) is in the range of 3.0%-3.5%, indicating that this method has the potential to be applied in clinical and biological samples quantitative analysis.

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.