Application of nucleic acid aptamer-based lateral flow assay in microbe detection

Abstract

<p indent="0mm">Microbial contamination and infection are global issues in the food and environmental fields that seriously threaten human health. Bacteria and fungi can easily cause food spoilage, resulting in diarrhea and vomiting; viruses can infect humans through different transmission routes, causing severe or even fatal harm. Hence, rapid analysis and identification of pathogenic microorganisms and simultaneous detection of multiple types of microbes have become hot research topics in biochemical analysis and molecular diagnosis. The lateral flow assay (LFA) is a simple, rapid, economical, and efficient detection technology with high sensitivity, simple operation, and environmental friendliness. It can provide instant test results under non-laboratory circumstances, hence becoming an ideal choice for point-of-care testing, which has been applied to rapidly detect various targets. The current conventional principle of the LFA is still based on the specific recognition of the antigen by the antibody. However, as a commonly used target recognition molecule in conventional biochemical and medical detection, the application of antibodies also has certain limitations for rapid and accurate identification of certain targets due to strict control of the production and purification process, as well as susceptibility to the interference of the operating environment, pH, temperature, and other conditions, such as long production cycle, high cost, poor stability, and cross-reactivity. Aptamers are a class of single-stranded DNA (ssDNA) or RNA obtained through the systematic evolution of ligands by exponential enrichment (SELEX), which can usually form a stable secondary structure. Aptamers can be folded into a three-dimensional structure through conformational change and interact with the target through conformation complementarity, π-π stacking between aromatic rings, base stacking, electrostatic interaction, and hydrogen bonding. So far, nearly 300 kinds of aptamers have been discovered. As alternatives, aptamers are easy and facile to modify and label with high sensitivity and specificity. Accordingly, the innovative rapid detection technique can be developed by combining the LFA with an aptamer. This aptamer-based LFA technology can be widely used in qualitative, semi-quantitative, and quantitative detection in food safety, environment, clinical, and other fields. Nowadays, most microbe detection methods are constructed based on this approach. The common strategies of aptamer-based LFAs include the sandwich method, competitive method, and adsorption–desorption method. Diverse ingenious materials such as gold nanoparticles and quantum dots have also been proposed for signal read-out. Different signal capture models, such as colorimetric and fluorescence methods, have been applied for sensitive and accurate detection of a single or multiple target microbe. Furthermore, in view of the unique properties of nucleic acid aptamers, several signal amplification methods can be further involved in the LFA to enhance the sensitivity for target detection. This review introduces the use of aptamers with different structural patterns and labeling types in recent years, as well as a variety of methods to detect microbes, especially for the rapid detection of pathogenic bacteria. Based on the excellent characteristics, the aptamer-based LFA presents more flexibility and selectivity for microbe detection with good applicability, specificity, and sensitivity and can better achieve low-cost, rapid detection. This study is expected to provide a reference for developing nucleic acid aptamer-based LFA technologies, especially for efficient and accurate diagnosis of corona virus disease 2019 (COVID-19), exploiting the novel application scope of LFA technology.