Highly Sensitive and Rapid Identification of Streptococcus agalactiae Based on Multiple Cross Displacement Amplification Coupled With Lateral Flow Biosensor Assay

Ultra-Fast Impedimetric Immunoassay for Detection of Streptococcus agalactiae Using Carbon Electrode with Nanodiamonds Film

This publication presents the results of work on the development of a quick and cheap electrochemical immunosensor for the diagnosis of infections with the pathogen Streptococcus agalactiae. The research was carried out on the basis of the modification of the well-known glassy carbon (GC) electrodes. The surface of the GC (glassy carbon) electrode was covered with a film made of nanodiamonds, which increased the number of sites for the attachment of anti-Streptococcus agalactiae antibodies. The GC surface was activated with EDC/NHS (1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide/N-Hydroxysuccinimide). Determination of electrode characteristics after each modification step, performed using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).

Naked-eye detection strategies coupled with isothermal nucleic acid amplification techniques for the detection of human pathogens

Nucleic acid amplification-based techniques have gained acceptance by the scientific, and general, community as reference methodologies for many different applications. Since the development of the gold standard of these techniques, polymerase chain reaction (PCR), back in the 1980s many improvements have been made, and alternative techniques emerged reporting improvements over PCR. Among these, isothermal amplification approaches resulted of particular interest as could overcome the need of specialized equipment to accurately control temperature changes, but it was after year 2000 that these techniques have flourished in a huge number of novel alternatives with many different degrees of complexities and requirements. An added value is their possibility to be combined with many different naked-eye detection strategies, simplifying the resources needed, allowing to reduce cost, and serving as the basis for novel developments of lab-on-chip systems, and miniaturized devices, for point-of-care testing. In this review, we will go over different types of naked-eye detection strategies, combined with isothermal amplification. This will provide the readers up-to-date information for them to select the most appropriate strategies depending on the particular needs and resources for their experimental setup.

A Nanoparticle-Based Biosensor Combined With Multiple Cross Displacement Amplification for the Rapid and Visual Diagnosis of Neisseria gonorrhoeae in Clinical Application

Gonorrhea is a sexually transmitted disease caused by the host-adapted human pathogen, Neisseria gonorrhoeae. The morbidity is increasing and poses a major public health concern, especially in resource-scarce regions. Therefore, a rapid, visual, sensitive, specific, cost-saving, and simple assay for N. gonorrhoeae detection is critical for prompt treatment and the prevention of further transmission. Here, for the first time, we report a novel assay called the multiple cross displacement amplification combined with gold nanoparticle-based lateral flow biosensor (MCDA-LFB), which we constructed for the rapid and visual identification of N. gonorrhoeae in clinical samples. We successfully devised a set of MCDA primers based on the N. gonorrhoeae-specific gene, orf1. Optimal assay conditions were determined at 67°C, including genomic DNA preparation (∼15 min), MCDA amplification (30 min), and LFB reading (∼2 min), which can be completed within 50 min. The limit of detection (LoD) of the assay was 20 copies/test (in a 25-μl reaction mixture). Assay specificity was 100%, with no cross-reactions with other pathogens. Thus, our N. gonorrhoeae-MCDA-LFB is a rapid, specific, visual, cost-saving, and easy-to-use assay for N. gonorrhoeae diagnostics, and may have great potential for point-of-care (POC) testing in clinical settings, especially in resource-limited regions.