Sensitive and Extraction-Free Detection of Methicillin-Resistant Staphylococcus aureus through Ag + Aptamer-Based Color Reaction

• Published in: Journal of microbiology and biotechnology 2024-01, Vol.34 (1), p.192-197
• Main Authors: Hongli Cao, Guosheng Zhang, Hui Ma, Zhongwen Xue, Ran Huo, Kun Wang, Zijin Liu
• Format: Article
• Language: Korean
• Subjects: exonuclease-III; Methicillin-resistant Staphylococcus aureus; PBP2a aptamer; silver ion
• ISSN: 1017-7825; 1738-8872

Refractory infections, such as hospital-acquired pneumonia, can be better diagnosed with the assistance of precise methicillin-resistant Staphylococcus aureus (MRSA) testing. However, traditional methods necessitate high-tech tools, rigorous temperature cycling, and the extraction of genetic material from MRSA cells. Herein, we propose a sensitive, specific, and extraction-free strategy for MRSA detection by integrating allosteric probe-based target recognition and exonuclease-III (Exo-III)-enhanced color reaction. The penicillin-binding protein 2a (PBP2a) aptamer in the allosteric probe binds with MRSA to convert protein signals to nucleic acid signals. This is followed by the DNA polymerase-assisted target recycle and the production of numerous single-strand DNA (ssDNA) chains which bind with silver ion (Ag + ) aptamer to form a blunt terminus that can be identified by Exo-III. As a result, the Ag + aptamer pre-coupled to magnetic nanoparticles is digested. After magnetic separation, the Ag + in liquid supernatant catalyzes 3,3’,5,5’-tetramethylbenzidine (TMB) for a color reaction. In addition, a concentration of 54 cfu/mL is predicted to be the lowest detectable value. Based on this, our assay has a wide linear detection range, covering 5 orders of magnitude and demonstrating a high specificity, which allows it to accurately distinguish the target MRSA from other microorganisms.