Highly sensitive detection of multiple antibiotics based on DNA tetrahedron nanostructure-functionalized magnetic beads.

Functional DNAs-functionalized magnetic beads (MBs) offer great potential in bioanalysis field because of their target recognition and magnetic separation functions. However, the recognition capability and hybridization affinity of DNA probes often suffer from limited available space, poor probe conformation and non-selective adsorption. To overcome these limitations, we herein used aptamer-pendant DNA tetrahedron nanostructure-functionalized MBs (TETapt-tet MBs) to develop a target-response fluorescence method with tetracycline (TET) as a model. In the absence of TET, 6-carboxy-X-rhodamine-labeled complementary DNAs (ROX-cDNAs) were assembled on the surface of MBs. Upon the addition of target TET, the ROX-cDNAs were separated and released from the MBs to generate fluorescence signal. The limit of detection and limit of quantification for TET were found to be 6 pg mL-1 and 20 pg mL-1, respectively. Compared with ssDNA-functionalized MBs surface, the designed DNA tetrahedron nanostructure-based surface could decrease the hybridization time and reduce false positives, ensuring the accuracy of TET detection in complex samples. The presented method was successfully employed for TET detection in honey samples. Moreover, this functionalization strategy could be extended to detect multiple antibiotics by simply substituting different aptamer sequences. Therefore, the proposed method has great potential in the field of food safety and public health.

[Performance evaluation of Mindray BS-200 automatic biochemistry analyzer].

OBJECTIVE: To evaluate the main performance of BS-200 automatic biochemistry analyzer. METHODS: To evaluate the repeatability, linearity, precision and accurate Of the BS-200 automatic biochemistry analyzer by 8 items that contain all wavelength (ALT, GGT, Cl-, Cr, Glu, TP, Alb. APOA1. TBil), and carry on the contrast experiment with Hitachi 7170. RESULTS: The daytime run CV,within-run CV between-run CV and total CV are under 4.0%, the duplication is well, the accuracy is high, the linear scope is wide, and the contrast experiment correlation is good. CONCLUSION: This instrument each appraisal target is good, and worth in the small or middle-sized hospital promotion application.