School of Food and Bioengineering, Xihua University, Chengdu, 610000, China.
Chengdu Customs Technology Center, Chengdu, 610000, China; Food Safety Detection Key Laboratory of Sichuan Province, Chengdu, 610000, China.
Anal Chim Acta. 2023 Oct 2;1276:341618. doi: 10.1016/j.aca.2023.341618. Epub 2023 Jul 13.
Due to their superparamagnetism and enzyme-like activity, iron oxide (FeO) nanozymes can be readily used for sample pretreatment and the generation of detection signals, and have, thus, attracted much attention in the field of bioanalysis and diagnosis. However, the low catalytic activity of FeO nanozymes does reduce the sensitivity of FeO-based methods, limiting their application. In this study, FeO@Cu@poly(pyrrole-2-carboxylic acid) yolk-shell nanozymes (FeO@Cu@PCPy YSNs) were synthesized using a facile approach and selective chemical etching technology. Compared with FeO nanozymes, the FeO@Cu@PCPy YSNs demonstrated a three-fold increase in the peroxidase-like activity, good dispersity and strong superparamagnetism. In addition, the flower-shaped structure of aptamer-complementary strand (Apt-CS) conjugates was designed on the surface of the FeO@Cu@PCPy YSNs, which effectively inhibited their peroxidase-like activity by creating a physical barrier that hindered the access of substrates to the center of the FeO@Cu@PCPy YSNs. Based on this principle, a robust and facile colorimetric aptasensor was developed for detecting Salmonella Typhimurium. The flower-shaped Apt-CS were dissociated in the presence of S. Typhimurium, promoting the recovery of FeO@Cu@PCPy YSN catalytic activity. Under optimized conditions, this proposed aptasensor successfully detected S. Typhimurium in a linear range of 3 to 3 × 10 CFU/mL, achieving a detection limit of 1 CFU/mL. Finally, the feasibility of this novel aptasensor was further validated by three actual samples, with recoveries of between 84.3% and 102%, thereby demonstrating the huge potential of the proposed aptasensor for detecting S. Typhimurium in foods.
由于超顺磁性和类似酶的活性，氧化铁（FeO）纳米酶可用于样品预处理和检测信号的产生，因此在生物分析和诊断领域引起了广泛关注。然而，FeO 纳米酶的低催化活性确实降低了基于 FeO 的方法的灵敏度，限制了其应用。在本研究中，采用简便的方法和选择性化学刻蚀技术合成了 FeO@Cu@聚（吡咯-2-羧酸）核壳纳米酶（FeO@Cu@PCPy YSNs）。与 FeO 纳米酶相比，FeO@Cu@PCPy YSNs 的过氧化物酶样活性提高了三倍，具有良好的分散性和强超顺磁性。此外，在 FeO@Cu@PCPy YSNs 表面设计了适配体互补链（Apt-CS）缀合物的花形结构，通过创建物理障碍来有效抑制其过氧化物酶样活性，从而阻碍底物进入 FeO@Cu@PCPy YSNs 的中心。基于这一原理，开发了一种用于检测肠炎沙门氏菌的稳健且简便的比色适体传感器。在存在肠炎沙门氏菌的情况下，花形 Apt-CS 解离，促进了 FeO@Cu@PCPy YSN 催化活性的恢复。在优化条件下，该提出的适体传感器成功地在 3 到 3×10^CFU/mL 的线性范围内检测到肠炎沙门氏菌，检测限为 1 CFU/mL。最后，通过三个实际样品进一步验证了该新型适体传感器的可行性，回收率在 84.3%至 102%之间，从而证明了该适体传感器在食品中检测肠炎沙门氏菌的巨大潜力。
