Recent advances of lateral flow immunoassay for bacterial detection: Capture-antibody-independent strategies and high-sensitivity detection technologies

Bacterial infectious diseases are still one of the leading causes of human death in the world, especially in less developed countries. Up-to-date diagnostics are globally improved by bedside research works and point-of-care testing. Lateral flow immunoassays (LFIAs) have achieved considerable commercial success and attracted a lot of interest owing to their noteworthy advantages including portability, cost-effectiveness, user-friendliness and rapid detection. In the traditional LFIA for pathogens detection, capture antibody (CA) is necessary to conjugate with nanomaterials (NMs) to prepare NMs-CA probe for labeling targets. However, the biological activity of CA could be affected by some factors, and the process of obtaining NMs-CA probes is usually comparatively complex and expensive. Besides, conventional LFIAs are usually performed by observing the color changes of strips with naked eye, but this readout method is not quantitative and lacks adequate sensitivity required for a reliable assay. Several novel CA-independent methods and diverse high-sensitivity signal readout LFIA detection technologies have been developed. In this review, we summarized seven principles of CA-independent LFIA strategy including Van Der Waals forces, hydrogen bond, electrostatic adsorption, hydrophobic interaction, mannose-FimH recognition, cell wall binding domain-ligand recognition and covalent bond. Besides, an objective and critical overview of the latest advances in technologies for high-sensitivity LFIA was provided. In addition, future prospects and challenges of LFIA for bacterial detection were also discussed.