One lead to numerous: A DNA concatemer-based fluorescence aptasensor for selective and sensitive Acinetobacter baumannii detection

Abstract

Rapid and precise analysis of Acinetobacter baumannii plays a crucial role in inhibition of healthcare-associated infectious diseases and development of optimal treatment strategies. Previously reported fluorescence sensors have been promising, but were hindered by poor selectivity and low sensitivity due to the complex detection environment and limited identification ability. Thus, specifically recognised and effectively amplified strategies are vital for overcoming the shortcomings of existing analytical methods. Herein, a highly sensitive and selective fluorescence aptasensor was constructed for the quantification of A. baumannii based on aptamer-mediated DNA concatemers. The self-assembled DNA concatemers were anchored on the surface of micromagnetic beads by aptamers as an intermediation embellished with numerous carbon quantum dots (CQDs). Effective recognition and capture of A. baumannii cells by the aptamer immediately triggered the release of DNA concatemers. Meanwhile, a magnified fluorescent signal wherein a single A. baumannii cell results in numerous CQDs would be generated. The as-prepared biosensor exhibited an excellent detection and quantification limit (LOD) as 52.67 (11.20) cells/mL, LOQ = 155.3 (10.80) cells/mL over a wide linear range (9.80×102 to 1.25×105 cells/mL) for A. baumannii analysis, which was superior to previously reported methods. Furthermore, the sensor exhibited satisfactory accuracy and good reproducibility in urine samples obtained from patients with bladder cancer and healthy individuals.