Tandem Förster resonance energy transfer induced visual ratiometric fluorescence sensing of tetracyclines based on zeolitic imidazolate framework-8 incorporated with carbon dots and safranine T.

Developing new methods for efficiently detecting tetracycline antibiotics in water has gained much importance. In this work, zeolitic imidazolate framework-8 (ZIF-8) was used as a host to encapsulate carbon dots (CDs) and safranine T (ST) during its self-assembly process to synthesize CDs/ST@ZIF-8, which was then applied as the dual-emissive probe for detecting tetracycline antibiotics. Benefiting from the confinement effects of ZIF-8 and its fluorescence enhancement effects toward tetracycline (TC), a unique tandem Förster resonance energy transfer (FRET) system from CDs to TC and then to ST could be established, with a low limit of detection of 46 nM and excellent selectivity.

[Ssp DnaB intein-mediated ligation of heavy and light chains of coagulation factor VIII in Escherichia coli].

We studied the ligation of coagulation factor VIII heavy and light chains in Escherichia coli by utilizing the intein-mediated protein trans-splicing. A B-domain deleted factor VIII (BDD-FVIII) gene was broken into two halves of heavy and light chains before Ser1657 which meets the splicing required conserved residue and then fused to 106 and 48 amino acid-containing N-part termed Int-N and C-part termed Int-C coding sequences of split mini Ssp DnaB intein respectively. These two fusion genes were constructed into a prokaryotic expression vector pBV220.