Specific and ultrasensitive detection of Staphylococcus aureus with a catechol-chitosan redox capacitor based electrochemical aptasensor

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• To construct an ultrasensitive electrochemical aptasensor for S. aureus analysis. • Preparation of a redox capacitor amplification system to improve sensitivity. • The aptasensor shows an LOD of 2 CFU/mL and a detection time of 25 mins. • The aptasensor shows good adaptability to real blood samples. The effective and accurate detection of Staphylococcus aureus ( S. aureus ) is of great importance for quickly treating infected patients, preventing the spread of infection and reducing the formation of resistant strains. This paper describes an electrochemical aptasensor for specific and ultrasensitive detection of S. aureus by combining a redox capacitor amplification system and a specific aptamer. The redox capacitor amplification system was constructed using catechol-chitosan film and 1,1′-ferrocene dimethanol (Fc)-hexaammineruthenium (III) chloride (Ru 3+ ) mediators. The aldehyde-modified aptamer was immobilized on the electrode surface by the Schiff base reaction with the amino groups of chitosan and served as a specific biological recognition element for S. aureus . The proposed electrochemical aptasensor presented great performance in terms of detection time (25 min), linear range (10 ∼ 10 8 cfu/mL) and detection limit (2 cfu/mL). The proposed biosensor also displayed good reproducibility and selectivity. The electrochemical apatsensor can quantitatively and directly detect S. aureus in whole blood samples (the spiked recovery rate was 90.5–100.1%), laying the foundation for its clinical application.