Fluorescent aptasensor for antibiotic detection using magnetic bead composites coated with gold nanoparticles and a nicking enzyme

• Published in: Analytica chimica acta 2017-09, Vol.984, p.177-184
• Main Authors: Luo, Zewei, Wang, Yimin, Lu, Xiaoyong, Chen, Junman, Wei, Fujing, Huang, Zhijun, Zhou, Chen, Duan, Yixiang
• Format: Article
• Language: English
• Subjects: Abuse; Ampicillin; Anti-Bacterial Agents - analysis; Antibiotics; Aptamers; Aptamers, Nucleotide; Beads; Biosensing Techniques; Complementary DNA; Conjugation; Deoxyribonucleic acid; DNA; DNA probes; Environmental health; Enzymes; Fluorescence; Fluorescent aptasensor; Fluorescent indicators; Gold; Gold nanoparticles; Humans; Limit of Detection; Magnetic beads; Magnetic separation; Metal Nanoparticles; Nanoparticles; Nicking endonuclease; Nicking enzyme; Occupational health; Polyethyleneimine; Public health; Scaffolds; Studies; Water pollution
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2017.06.037

Antibiotic abuse has been bringing serious pollution in water, which is closely related to human health. It is desirable to develop a new strategy for antibiotic detection. To address this problem, a sensitive fluorescent aptasensor for antibiotic detection was developed by utilizing gold nanoparticles modified magnetic bead composites (AuNPs/MBs) and nicking enzyme. AuNPs/MBs were synthesized with the help of polyethylenimine (PEI). The prepared AuNPs/MBs acted as dual-functional scaffolds that owned excellent magnetic separation capacity and strong covalent bio-conjugation. The non-specifically absorbed aptamers in AuNPs/MBs were less than that in MBs. Hence, the fluorescent aptasensor based on AuNPs/MBs show a better signal to background ratio than that based on carboxyl modified magnetic beads (MBs). In this work, ampicillin was employed as a model analyte. In the presence of ampicillin, the specific binding between ampicillin and aptamer induced structure-switching that led to the release of partial complementary DNA (cDNA) of aptamer. Then, the released cDNA initiated the cycle of nicking enzyme assisted signal amplification (NEASA). Therefore, a large amount of taqman probes were cleaved and fluorescence signal was amplified. The prepared fluorescent aptasensor bring sensitive detection in range of 0.1–100 ng mL−1 with the limit of detection of 0.07 ng mL−1. Furthermore, this aptasensor was also successfully applied in real sample detection with acceptable accuracy. The fluorescent aptasensor provides a promising method for efficient, rapid and sensitive antibiotic detection. [Display omitted] •A sensitive fluorescent aptasensor for ampicillin detection.•An effective scaffold of AuNPs/MBs with magnetic separation capacity and bioconjugation of high quality.•AuNPs/MBs coupled with NEASA were used to construct fluorescent aptasensors with competitive performance.