Jun Hu,Chaohui Zhan,Qiu Wang,Hongyang Shi,Yong He,Aiguo Ouyang
Food such as cereal crops, oil crops and dairy products are very easy to produce highly toxic and carcinogenic aflatoxins during inappropriate storage. Therefore, it is of great significance to achieve rapid, non-destructive and highly sensitive detection of aflatoxin. A terahertz metamaterial sensor with “X” compound double-peak structure is designed based on electromagnetic theory to realize highly sensitive detection of aflatoxin B2 solution. It is found that the amplitude of the transmission peak of the terahertz transmission spectrum of aflatoxin B2 (AFB2) solution around 1.2 THz and 2.0 THz gradually decreased with the increase of the concentration of aflatoxin B2 solution, and the frequency of the transmission peak gradually shifted to high frequency with the increase of the concentration of aflatoxin B2 solution, hence a full concentration model was established. And a strategy of first classifying concentration intervals and then building a grouped quantitative model was proposed. The Limit of Detection ( LOD ) of the interval sub-model of low and medium concentration of aflatoxin B2 solution has been greatly improved with the LOD of the optimal grouping model was 7.28 × 10 −11 mg/ml, 4.19 × 10 −9 mg/ml and 1.22 × 10 −7 mg/ml, respectively. This research verifies the feasibility of terahertz metamaterial sensor based on “X” composite double-peak structure combined with THz-TDS technology for highly sensitive detection of aflatoxin B2 solution. And it provides a new rapid, non-destructive and highly sensitive detection of aflatoxin in food.
Rapid and simple detection of carbapenem-resistant Enterobacteriaceae (CRE) is important to manage infection and prevent the spread of these bacteria. In this work, we utilize pH response to detect CRE in urine rapidly. By using vancomycin-modified Fe3O4@Au nanoparticles (Fe3O4@Au@VanNPs), CRE in urine were enriched and separated efficiently via vancomycin–cell wall interaction. More importantly, carbapenemases released via CRE lysis were detected using a pH metre which responded to hydrogen ions generated from imipenem hydrolysis. Thus, the concentration of CRE in urine was detected via the carbapenemase hydrolysis reaction. The proposed method demonstrated a good linear relationship in the range of 104–108 cfu mL−1 for CRE with the limit of detection estimated to be 1.0 × 103 cfu mL−1. More importantly, this method successfully detected clinically isolated CRE strains in urine samples within 3.5 h. Thus, this biosensing strategy might have the potential for practical application in the rapid detection of various resistant bacteria.
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