Solvent-free magnetic-tip microextraction into a single drop for fluorescence sensing

In this work, a simple fluorescence sensing device based on an approach of solvent-free magnetic-tip microextraction into a single drop was developed. As proof-of-principle, the strategy was used to extract chloramphenicol (CAP). CAP was selectively recognized by a DNA-aptamer and replaced by a trigger in the assay. By combining DNA signal amplification, DNA walkers constructed DNA chains with G-quadruplex/protoporphyrin IX (PPIX) as the...