Detection of Escherichia coli in drugs with antibody conjugated quantum dots as immunofluorescence probes

► A rapid and specific method of determining Escherichia coli in drugs was demonstrated with bioactive antibody-conjugated QDs. ► IgG-QDs could selectively recognize E. coli that could avoid false positive. ► The stressed and injured E. coli can be detected which would not cause false negative. ► Cell recovery rates for E. coli were 82.90% and 73.64% respectively with the entire detecting process of only less than 4 h.