Acinetobcter baumannii (A. baumannii) is responsible for various nosocomial infections, which is known as clinically important opportunistic pathogen. Therefore, rapid detection of this pathogen is critical to prevent the spread of infection and appropriate treatment [1]. Various methods have been developed for the detection of A. baumannii, such as antibody-based assays, bacterial culture, nucleic acid-based assays, biochemical assays and surface-enhanced Raman scattering [2]. Most of them are accurate but are accompanied by several problems in on-site detection, such as procedures being complicated and cumbersome, time is long, sensitivity is limited, highly sophisticated instruments and expensive, skilled manpower and the cost is high [2]. Therefore, to combat the aforementioned challenges, there is an urgent need for new powerful tools that are rapid and sensitive with the ability to detect A. baumannii on-site and that can guide the concerned person for taking appropriate control measures. Among various detection techniques, electrochemical methods have been recognized as one of the most promising technologies due to their high sensitivity, fabrication simplicity, accuracy, cost-effectiveness, selectivity, the possibility of mass production and ease of modification [3,4]. In the past few years, aptasensors were used for detecting the type of some bacteria [5,6]. In this study, the objective was to develop highly sensitive electrochemical aptasensor for the detection of A. baumannii bacteria. The carbon screen-printed electrode (CSPE) surface was modified with the synthesized rGO-MWCNT/CS/CQD to significantly increase the effective surface area of the electrode and for further aptamer immobilization at the surface. The aptamer was used as a capture probe for the recognition of A. baumannii on the surface of rGOMWCNT/CS/CQD/CSPE. Also, aptamer immobilized on hemin (H)-graphite oxide (H-GO/ Aptamer) was utilized as an electrochemical signal reporter probe by H reduction. By labeling the aptamer on H-GO, the surface density of the aptamer was increased, resulting in enhanced detection sensitivity. Additionally, a sandwich-type electrochemical aptasensor was introduced using HGO/Aptamer to detect A. baumannii. The resultant synthesized compounds were thoroughly characterized using Fourier transform infrared (FT-IR), X-Ray diffraction (XRD), and field emission scanning electron microscopy (FE-SEM) techniques. Furthermore, under optimized experimental conditions, the aptasensor was demonstrated to be capable of detecting A. baumannii with a linear range of (10.00 to 107 Colony-forming unit (CFU)/mL) and a limit of detection (LOD) of 1 CFU/mL (σ = 3). The developed aptasensor was able to successfully monitor A. baumannii in healthy human blood serum and skim milk powder samples and provided satisfactory results. The use of this aptasensor could potentially aid in the early detection and diagnosis of A. baumannii infections, which is crucial in preventing further spread. Overall, the design and development of ultrasensitive electrochemical aptasensors for the detection of A. baumannii is a promising approach to improve disease diagnosis and management. Further research and optimization of these aptasensors could lead to their widespread use in clinical settings.
