An electrochemical aptasensor based on target triggered multiple-channel DNAzymes cycling amplification strategy with PtFe@Co-MOF as signal amplifier.

A novel electrochemical aptasensor for the detection of Aflatoxin B1 (AFB1) was developed for the first time by using the target-triggered multiple-channel deoxyribozymes (DNAzymes) cycling amplified assay with Pt Fe doped NH2-Co-MOF (PtFe@Co-MOF) as a signal amplifier. In the presence of AFB1, a self-assembling cross-over nucleic structure could be triggered by AFB1 via two aptamers' structure switching for strand displacement, resulting in four channels of Mg2+-dependent DNAzyme recycling simultaneously to multiply the detection signals. These DNAzymes cyclically split the substrate sequence to release the PtFe@Co-MOF labeled detection probe (DP), which is subsequently hybridized with the capture probes on the Au-deposited glassy carbon electrode. The fabrication procedure was characterized by differential pulse voltammetry, and the results of the morphological and element composition characteristics methods were analyzed to determine the successful preparation of PtFe@Co-MOF. The limit of detection (LOD) for AFB1 detection was 2 pg mL-1 with a linear range from 5 pg mL-1 to 80 ng mL-1. By comparison, the enhanced detection sensitivity has been found to originate from the efficient shearing of DNAzymes, enhanced peroxidase-like capability, and multiple active sites of PtFe@Co-MOF. Besides, this aptasensor showed high specificity for AFB1 compared with similar mycotoxins and exhibited high accuracy with low experimental cost and easy operation. Furthermore, the unique design of electrochemical aptasensors could provide a promising platform for the onsite determination of AFB1, as well as other targets by replacing the aptamer and other core recognition sequences.

Effects Of Minocycline Combined With Tinidazole For Treatment Of Chronic Periodontitis.

Purpose: To investigate the therapeutic effects of minocycline combined with tinidazole in the treatment of chronic periodontitis (CP). Methods: Seventy-three CP patients treated May 2018­December 2019 at Yuyao People's Hospital (Yuyao, China) were enrolled in this study: 34 were treated with minocycline alone (control group; CG) and 39 were treated with a combination of minocycline and tinidazole (observation group; OG). Both groups were treated continuously for four weeks and plaque index (PLI), bleeding index (BI), periodontal pocket depth (PD), periodontal attachment level (PAL) and alveolar bone height were compared before and after treatment. Pain was evaluated using the visual analogue scale (VAS). Levels of TNF-α and IL-6 before and after treatment were determined using an enzyme-linked immunosorbent assay. Adverse reactions were compared. Results: In each group, PLI, BI, PD, PAL and alveolar bone height were lower after treatment (P<0.05), and those in OG were lower than those in CG (P<0.05). TNF-α and IL-6 levels in both groups were lower after treatment (P<0.05), and the levels in serum of the OG were lower than those of the CG (P<0.05). After treatment, the VAS in OG was lower than that of CG (P<0.05). There was no significant difference in adverse reactions between groups (P>0.05). Conclusion: Minocycline combined with tinidazole was more effective in treating CP than minocycline alone. This drug combination improved the periodontal indexes and inflammatory reaction of CP and relieved their pain. No significant difference in adverse reactions was seen.