Aptasensor for the Detection of Moraxella catarrhalis Adhesin UspA2

Aptamer-based therapy for fighting biofilm-associated infections

Biofilms are key players in the pathogenesis of most of chronic infections associated with host tissue or fluids and indwelling medical devices. These chronic infections are hard to be treated due to the increased biofilms tolerance towards antibiotics in comparison to planktonic (or free living) cells. Despite the advanced understanding of their formation and physiology, biofilms continue to be a challenge and there is no standardized therapeutic approach in clinical practice to eradicate them. Aptamers offer distinctive properties, including excellent affinity, selectivity, stability, making them valuable tools for therapeutic purposes. This review explores the flexibility and designability of aptamers as antibiofilm drugs but, importantly, as targeting tools for diverse drug and delivery systems. It highlights specific examples of application of aptamers in biofilms of diverse species according to different modes of action including inhibition of motility and adhesion, blocking of quorum sensing molecules, and dispersal of biofilm-cells to planktonic state. Moreover, it discusses the limitations and challenges that impaired an increased success of the use of aptamers on biofilm management, as well as the opportunities related to aptamers modifications that can significantly expand their applicability on the biofilm field.

Rapid and reliable diagnosis of Moraxella catarrhalis infection using loop-mediated isothermal amplification-based testing

Moraxella catarrhalis (M. catarrhalis) was an important pathogen closely associated with respiratory tract infections. We employed the loop-mediated isothermal amplification (LAMP) coupled with nanoparticle-based lateral flow biosensor (LFB) and fluorescence testing technique for formulating two diagnostic methods for M. catarrhalis detection, termed M. catarrhalis-LAMP-LFB assay and M. catarrhalis-LAMP-FRT, respectively. The M. catarrhalis-LAMP-LFB system incorporated the use of biotin-14-dCTP and a forward loop primer (LF) with a hapten at the 5' end. This design in LAMP reaction enabled the production of double-labeled products that could be effectively analyzed using the lateral flow biosensor (LFB). For the M. catarrhalis-LAMP-FRT assay, the LF was modified with a sequence at 5' end, and a fluorophore, as well as a black hole quencher, were strategically labeled at the 5' end and within the middle of the new LF. The restriction endonuclease Nb.BsrDI could accurately recognize and cleave the newly synthesized double-strand terminal sequences, resulting in the separation of the fluorophore from the black hole quencher and releasing fluorescence signals. Both assays have been proven to be highly sensitive and specific, capable of detecting genomic DNA of M. catarrhalis at concentrations as low as 70 fg, with no cross-reactivity observed with non-M. catarrhalis pathogens. Furthermore, both methods successfully identified M. catarrhalis in all clinical samples within 1 h that were confirmed positive by real-time PCR, exhibiting superior sensitivity than conventional culture methods. Herein, the newly developed two LAMP-based assays were rapid and reliable for M. catarrhalis detection and hold significant promise for deployment in point-of-care (POC) settings.