A lateral flow strip biosensor platform based on cascade nucleic acid amplification technology for ultrasensitive detection of OSCC-associated salivary MicroRNA

Lateral flow strip assay of a gene segment in the COVID-19 virus with combined dual readout mode and preliminary multisite hybrid chain reaction amplification

The past and present scenario of COVID-19 has revealed the necessity of simple point-of-care tests. When combined with the great advantages of amplification, lateral flow assay nucleic acid analysis represents a more sensitive molecular diagnostic technique compared to universal protein analysis. Room temperature operation, an enzyme-free nature, and in situ elongation make hybrid chain reaction amplification (HCR) a good candidate for amplified combined lateral flow assays (LFAs). Since dual modes of detection can not only satisfy different application scenarios, but also reduce the false-negative rate, in this paper, visual and fluorescent detection based on labelling with colloidal gold nanoparticles and fluorescence labelling were incorporated into a HCR integrated with a LFA. The detection assay was finished in 30 minutes. The linear relationship between the signal and the concentration of the characteristic segment in the COVID-19 ORF gene was demonstrated. The obtained detection limits of as low as 10 fM (6.02 × 103 copies per mL) and 1 fM (6.02 × 102 copies per mL), respectively, were comparable with those in the literature. The multi-site HCR amplification integrated with LFA of a 1053 bp nucleic acid chain was also preliminarily studied, and tri-site amplification was found to exhibit higher signal intensity than single-site amplification. This study provides a promising strategy for simple, sensitive, and wide-ranging detection of pathogenic bacteria.

Sample-to-answer salivary miRNA testing: New frontiers in point-of-care diagnostic technologies

MicroRNA (miRNA), crucial non-coding RNAs, have emerged as key biomarkers in molecular diagnostics, prognosis, and personalized medicine due to their significant role in gene expression regulation. Salivary miRNA, in particular, stands out for its non-invasive collection method and ease of accessibility, offering promising avenues for the development of point-of-care diagnostics for a spectrum of diseases, including cancer, neurodegenerative disorders, and infectious diseases. Such development promises rapid and precise diagnosis, enabling timely treatment. Despite significant advancements in salivary miRNA-based testing, challenges persist in the quantification, multiplexing, sensitivity, and specificity, particularly for miRNA at low concentrations in complex biological mixtures. This work delves into these challenges, focusing on the development and application of salivary miRNA tests for point-of-care use. We explore the biogenesis of salivary miRNA and analyze their quantitative expression and their disease relevance in cancer, infection, and neurodegenerative disorders. We also examined recent progress in miRNA extraction, amplification, and multiplexed detection methods. This study offers a comprehensive view of the development of salivary miRNA-based point-of-care testing (POCT). Its successful advancement could revolutionize the early detection, monitoring, and management of various conditions, enhancing healthcare outcomes. This article is categorized under: Diagnostic Tools > Biosensing Diagnostic Tools > Diagnostic Nanodevices.

Label-free and highly sensitive detection of microRNA from cancer cells via target-induced cascade amplification generation of lighting-up RNA aptamers

The abnormal expression levels of miRNAs have been proven to be highly related to the generation of various diseases and are also closely associated with the stages and types of disease development. The novel RNA aptamers-based homogenous fluorescent methods were simple, with low background signal and high signal-to-noise ratio, but lacked effective signal amplification technology to achieve sensitive detection of trace miRNA markers. There is an urgent need for combining effective nucleic acid amplification technology with RNA aptamer to achieve highly sensitive and accurate detection of miRNA. For this purpose, a new DNA multi-arm nanostructure-based dual rolling circle transcription machinery for the generation of lighting-up MG RNA aptamers is constructed for label-free and highly sensitive sensing of miRNA-21. In this system, the target miRNA-21 induces a structural transformation of the DNA multi-arm nanostructure probe to recycle miRNA-21 and trigger two independent rolling circle transcription reactions to generate two long RNAs, which can partially hybridize with each other to generate large amounts of complete MG RNA aptamers. These RNA aptamers can associate with organic MG dye to produce significantly enhanced fluorescence signals to accomplish ultrasensitive miRNA-21 detection down to 0.9 fM. In addition, this method exhibits high selectivity to distinguish miRNA-21 even with single nucleotide mismatch, and also has potential application capability to monitor different expression levels of miRNA-21 from different cancer cells. The effective collaboration between MG RNA aptamer and rolling circle transcription reaction makes this fluorescent method show the significant advantages of low background signal, high signal-to-noise ratio and high detection sensitivity. It has great potential to be a promising means to achieve label-free and highly sensitive monitoring of other trace biological markers via a simple change of target sequence.

Recent Uses of Paper Microfluidics in Isothermal Nucleic Acid Amplification Tests

Isothermal nucleic acid amplification tests have recently gained popularity over polymerase chain reaction (PCR), as they only require a constant temperature and significantly simplify nucleic acid amplification. Recently, numerous attempts have been made to incorporate paper microfluidics into these isothermal amplification tests. Paper microfluidics (including lateral flow strips) have been used to extract nucleic acids, amplify the target gene, and detect amplified products, all toward automating the process. We investigated the literature from 2020 to the present, i.e., since the onset of the COVID-19 pandemic, during which a significant surge in isothermal amplification tests has been observed. Paper microfluidic detection has been used extensively for recombinase polymerase amplification (RPA) and its related methods, along with loop-mediated isothermal amplification (LAMP) and rolling circle amplification (RCA). Detection was conducted primarily with colorimetric and fluorometric methods, although a few publications demonstrated flow distance- and surface-enhanced Raman spectroscopic (SERS)-based detection. A good number of publications could be found that demonstrated both amplification and detection on paper microfluidic platforms. A small number of publications could be found that showed extraction or all three procedures (i.e., fully integrated systems) on paper microfluidic platforms, necessitating the need for future work.

Leak-proof probe for accurate detection of Neisseria gonorrhoeae by recombinase polymerase amplification-mediated lateral flow strip

Neisseria gonorrhoeae is the only pathogen contributing to gonorrhea, a common infectious disease. Clinically, approximately 50-80% of female and 40% of male patients are asymptomatic, and these carriers are the key to gonorrhea transmission. The rapid detection of N. gonorrhoeae recessive infection is vital to curb the spread of gonorrhea. Therefore, the development of a specific, sensitive, rapid, and convenient method for the diagnosis of N. gonorrhoeae is a priority. In this study, we identified the highly conserved fitA gene of N. gonorrhoeae as a detection target through bioinformatics analysis. Then, we constructed a convenient, economical, and effective biosensor to detect N. gonorrhoeae without false-positive results based on recombinase polymerase amplification-mediated lateral flow strip by leak-proof probe. The biosensor has high sensitivity, is capable of detecting N. gonorrhoeae at concentrations as low as 10² copies/μL within 28 min, and has high specificity, which allows N. gonorrhoeae to be differentiated from other genito-urinary bacteria and fungi. Finally, this biosensor has been successfully applied to the detection of N. gonorrhoeae in clinical samples, and the results have been consistent with those determined using qRT-PCR.

Salivary Biomarkers in Oral Squamous Cell Carcinoma: A Proteomic Overview

BACKGROUND

Oral squamous cell carcinoma (OSCC) is one of the most frequent cancers worldwide. Endoscopic methods may be useful in the evaluation of oral injuries even though the diagnostic gold standard is a biopsy. Targeted screenings could be considered the best way to prevent the occurrence of oral cancer. Aimed to elucidate the potential identification of specific biomarkers of OSCC, the use of saliva is convenient and noninvasive. Many studies reported more than a hundred putative saliva biomarkers for OSCC, and proteogenomic approaches were fundamental to disclosing this issue.

METHODS

Relevant literature published in the last few years was systematically searched on PubMed and we focused on articles about the use and study of salivary biomarkers in the diagnostics of head and neck cancer (n = 110). Thereafter, we performed a selection focusing on diagnosis with salivary proteomics in OSCC (n = 8).

RESULTS

Saliva proteomics can be a source of biomarkers for OSCC. We reviewed literature of biomarker proteins in saliva that could also be evaluated as probable targets for non-invasive screening of oral neoplasm such as cytokines, matrix metalloproteinases, and acute-phase response proteins.

CONCLUSIONS

The measurement of salivary biomarkers is a highly hopeful technique for the diagnosis of OSCC. Proteogenomic approaches could permit an accurate and early diagnosis of OSCC. This review seeks to generate an up-to-date view on translational OSCC issues by raising awareness of researchers, physicians, and surgeons. Renewed clinical studies, which will validate the sensitivity and specificity of salivary biomarkers, are necessary to translate these results into possible strategies for early diagnosis of OSCC, thus improving patient outcomes.