Electroanalytical Chemistry Research Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran.
Electroanalytical Chemistry Research Laboratory, Department of Analytical Chemistry, Faculty of Chemistry, University of Mazandaran, Babolsar, Iran.
Anal Chim Acta. 2024 May 15;1303:342491. doi: 10.1016/j.aca.2024.342491. Epub 2024 Mar 16.
Acinetobacter baumannii (A. baumannii) is a pathogenic bacterium that causes severe infections and its rapid and reliable diagnosis is essential for effective control and treatment. In this study, we present an electrochemical aptasensor based on a signal amplification strategy for the detection of A. baumannii, the high specificity and affinity of the aptamer for the target make it favorable for signal amplification. This allows for a highly sensitive and selective detection of the target. The aptasensor is based on a carbon screen-printed electrode (CSPE) that has been modified with a nanocomposite consisting of multi-walled carbon nanotubes (MWCNTs), reduced graphene oxide (rGO), chitosan (CS), and a synthesized carbon quantum dot (CQD) from CS. Additionally, the self-assembled aptamers were immobilized on hemin-graphite oxide (H-GO) as a signal probe. The composition of the nanocomposite (rGO-MWCNT/CS/CQD) provides high conductivity and stability, facilitating the efficient capture of A. baumannii onto the surface of the aptasensor. Also, aptamer immobilized on Hemin-graphite oxide (H-GO/Aptamer) was utilized as an electrochemical signal reporter probe by H reduction. This approach improved the detection sensitivity and the aptamer surface density for detecting A. baumannii. Furthermore, under optimized experimental conditions, the aptasensor was demonstrated to be capable of detecting A. baumannii with a linear range of (10 - 1 × 10 Colony-forming unit (CFU)/mL) and a limit of detection (LOD) of 1 CFU/mL (σ = 3). One of the key features of this aptasensor is its ability to distinguish between live and dead bacteria cells, which is very important and critical for clinical applications. In addition, we have successfully detected A. baumannii bacteria in healthy human serum and skim milk powder samples provided using the prepared electrochemical aptasensor. The functional groups present in the synthetic CQD, rGO-MWCNT, and chitosan facilitate biomolecule immobilization and enhance stability and activity. The fast electron-transfer kinetics and high conductivity of these materials contribute to improved sensitivity and selectivity. Furthermore, The H-GO/Aptamer composite's large surface area increases the number of immobilized secondary aptamers and enables a more stable structure. This large surface area also facilitates more H loading, leading to signal amplification.
鲍曼不动杆菌（A.baumannii）是一种致病细菌，可引起严重感染，因此快速可靠的诊断对于有效控制和治疗至关重要。在本研究中，我们提出了一种基于信号放大策略的电化学适体传感器，用于检测 A.baumannii，适体对目标的高特异性和亲和力使其有利于信号放大。这使得对目标进行高度敏感和选择性检测成为可能。该适体传感器基于已用包含多壁碳纳米管（MWCNT）、还原氧化石墨烯（rGO）、壳聚糖（CS）和从 CS 合成的碳量子点（CQD）的纳米复合材料修饰的碳丝网印刷电极（CSPE）。此外，自组装适体被固定在血红素-氧化石墨（H-GO）上作为信号探针。纳米复合材料（rGO-MWCNT/CS/CQD）的组成提供了高导电性和稳定性，有利于将 A.baumannii 高效捕获到适体传感器的表面。此外，固定在血红素-氧化石墨（H-GO/Aptamer）上的适体被用作电化学信号报告探针，通过 H 还原。这种方法提高了检测灵敏度和适体表面密度，从而提高了检测 A.baumannii 的能力。此外，在优化的实验条件下，该适体传感器能够检测到线性范围为（10 - 1 × 10 菌落形成单位（CFU）/mL）的 A.baumannii，检测限（LOD）为 1 CFU/mL（σ= 3）。该适体传感器的一个关键特征是能够区分活细菌细胞和死细菌细胞，这对于临床应用非常重要。此外，我们还成功地使用制备的电化学适体传感器检测了健康人血清和脱脂乳粉样本中的 A.baumannii 细菌。合成 CQD、rGO-MWCNT 和壳聚糖中存在的功能基团有利于生物分子固定，并增强了稳定性和活性。这些材料的快速电子转移动力学和高导电性有助于提高灵敏度和选择性。此外，H-GO/Aptamer 复合物的大表面积增加了固定的二级适体数量，并使结构更加稳定。这种大表面积还促进了更多的 H 加载，从而实现了信号放大。
