Multiplex Nucleic Acid Assay of SARS-CoV-2 via a Lanthanide Nanoparticle-Tagging Strategy

Single Particle Analysis-Enhanced DNA Walking Machine for Sensitive miRNA Detection

DNA walking machines have achieved significant breakthroughs in areas such as biosensing, bioimaging, and early cancer diagnosis, facilitated by the self-assembly of DNA or its combination with other materials, such as magnetic beads and metal nanoparticles. However, current DNA walking machine strategies are constantly challenged by inadequate analytical sensitivity, while sophisticated signal amplification procedures are often indispensable. Single-particle inductively coupled plasma mass spectrometry (SP-ICPMS) provides superior sensitivity and can effectively discriminate between background noise and detected signals due to the large number of metal atoms in a nanoparticle and the concentrating effect of single nanoparticle detection. In this study, we present a novel approach utilizing single nanoparticle counting and duplex-specific nuclease (DSN)-assisted signal amplification to construct a 3D DNA walking machine for detecting the aggressive prostate cancer (PCa) biomarker miRNA-200c. The proposed strategy showed an improvement in sensitivity with a detection limit (LOD) of 0.93 pM (28 amol) and was successfully applied in human serum samples. To the best of our knowledge, this is the first report of the DNA walking machine with single nanoparticle counting study.

Metallic nanoplatforms for COVID-19 diagnostics: versatile applications in the pandemic and post-pandemic era

The COVID-19 pandemic, which originated in Hubei, China, in December 2019, has had a profound impact on global public health. With the elucidation of the SARS-CoV-2 virus structure, genome type, and routes of infection, a variety of diagnostic methods have been developed for COVID-19 detection and surveillance. Although the pandemic has been declared over, we are still significantly affected by it in our daily lives in the post-pandemic era. Among the various diagnostic methods, nanomaterials, especially metallic nanomaterials, have shown great potential in the field of bioanalysis due to their unique physical and chemical properties. This review highlights the important role of metallic nanosensors in achieving accurate and efficient detection of COVID-19 during the pandemic outbreak and spread. The sensing mechanisms of each diagnostic device capable of analyzing a range of targets, including viral nucleic acids and various proteins, are described. Since SARS-CoV-2 is constantly mutating, strategies for dealing with new variants are also suggested. In addition, we discuss the analytical tools needed to detect SARS-CoV-2 variants in the current post-pandemic era, with a focus on achieving rapid and accurate detection. Finally, we address the challenges and future directions of metallic nanomaterial-based COVID-19 detection, which may inspire researchers to develop advanced biosensors for COVID-19 monitoring and rapid response to other virus-induced pandemics based on our current achievements.

Isotope-encoded tetrahedral DNA for multiple SARS-CoV-2 variant diagnosis

The evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has posed an unprecedented demand for accurate and cost-effective diagnostic assays to discriminate between different variants. Whilst many bioassays have been successfully demonstrated for SARS-CoV-2 detection, diagnosis of its variants remains challenging and mainly relies on time-consuming and costly sequencing techniques. Herein, we proposed a triplevalent tetrahedral DNA nanostructure (tTDN) with three overhang isotope probes capable of multiplex simultaneous analysis. HV69/70 del (alpha-specific), K417N (beta-specific) and T478K (delta-specific) and omicron with common mutations above of the SARS-CoV-2 S gene were detected selectively with the aid of the TDN scaffold and MNAzyme system, and a sensitive strategy enabling the screening of four kinds of variants of concern (VOC) was achieved.

Study on the detection of anthrax by ICP-MS based on gold nanoparticle labeling

BACKGROUND

In recent years, inductively coupled plasma mass spectrometry (ICP-MS) has been widely used in the field of molecular biology because of its unique advantages. Anthrax is a widespread and long-standing infectious disease, which affects and restricts people's work and life seriously.

OBJECTIVE

The study goal is to develop a new method for the detection of anthrax.

METHODS

A rapid, sensitive and accurate method for the detection of anthrax characteristic DNA was proposed by combing gold nanoparticles (AuNPs) and inductively coupled plasma mass spectrometry.

RESULTS

The linear range of this method is 100-2500 pmol/L and the limit of detection of 16.61 pmol/L.

CONCLUSION

The proposed method has numerous advantages, including simplicity of operation, high sensitivity, and specificity, which provides a new idea for the detection of anthrax. Importantly, this methodology has good potential for the detection of other biological substances such as bacteria and viruses by changing the modification sequence on the nanoparticle probe.

Single-Molecule Evaluation of the SARS-CoV-2 Nucleocapsid Protein Using Gold Particle-in-a-Frame Nanostructures Enhanced Fluorescent Assay

Ultrasensitive evaluation of low-abundance analytes, particularly with limits approaching a single molecule, is a key challenge in the design of an assay for profiling severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen. Herein, we report an aptamer claw strategy for directly evaluating the SARS-CoV-2 antigen based on gold particle-in-a-frame nanostructures (Au PIAFs). Au PIAF was used as a metal-enhanced fluorescence material. The assay integrated with a microplate reader achieved a sensitivity of 44 fg·mL-1 in under 3 min and accurately detected the SARS-CoV-2 nucleocapsid protein (N protein) in human saliva samples. When our assay is combined with a single-molecule counting platform, the limit of detection can be as low as 0.84 ag·mL-1. This rapid and ultrasensitive assay holds promise as a tool for screening SARS-CoV-2 and other contagious viruses.

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.

Emerging Multiplex Nucleic Acid Diagnostic Tests for Combating COVID-19

The COVID-19 pandemic caused by SARS-CoV-2 has drawn attention to the need for fast and accurate diagnostic testing. Concerns from emerging SARS-CoV-2 variants and other circulating respiratory viral pathogens further underscore the importance of expanding diagnostic testing to multiplex detection, as single-plex diagnostic testing may fail to detect emerging variants and other viruses, while sequencing can be too slow and too expensive as a diagnostic tool. As a result, there have been significant advances in multiplex nucleic-acid-based virus diagnostic testing, creating a need for a timely review. This review first introduces frequent nucleic acid targets for multiplex virus diagnostic tests, then proceeds to a comprehensive and up-to-date overview of multiplex assays that incorporate various detection reactions and readout modalities. The performances, advantages, and disadvantages of these assays are discussed, followed by highlights of platforms that are amenable for point-of-care use. Finally, this review points out the remaining technical challenges and shares perspectives on future research and development. By examining the state of the art and synthesizing existing development in multiplex nucleic acid diagnostic tests, this review can provide a useful resource for facilitating future research and ultimately combating COVID-19.

Isothermal gene amplification coupled MALDI-TOF MS for SARS-CoV-2 detection

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been spreading worldwide for more than a year and has undergone several mutations and evolutions. Due to the lack of effective therapeutics and long-active vaccines, accurate and large-scale screening and early diagnosis of infected individuals are crucial to control the pandemic. Nevertheless, the current widely used RT-qPCR-based methods suffer from complicated temperature control, long processing time and the risk of false-negative results. Herein, we present a three-way junction induced exponential rolling circle amplification (3WJ-eRCA) combined MALDI-TOF MS assay for SARS-CoV-2 detection. The assay can detect simultaneously the target nucleocapsid (N) and open reading frame 1 ab (orf1ab) genes of SARS-CoV-2 in a single test within 30 min, with an isothermal process (55 °C). High specificity to discriminate SARS-CoV-2 from other coronaviruses, like SARS-CoV, MERS-CoV and bat SARS-like coronavirus (bat-SL-CoVZC45), was observed. We have further used the method to detect pseudovirus of SARS-CoV-2 in various matrices, e.g. water, saliva and urine. The results demonstrated a great potential of the method for large scale screening of COVID-19, which is an important part of the pandemic control.