Phosphorescent quantum dots/ethidium bromide nanohybrids based on photoinduced electron transfer for DNA detection

• The high water-solubility Mn-doped-QDs with good RTP property was synthesized.
• The RTP intensity of the QDs could be effectively quenched by EB.
• EB can be selectively separated from the QDs by DNA.
• The RTP of the QDs/EB nanohybrids was restored by DNA.
• The DNA sensor was applied to biological fluids with satisfactory results.

Mercaptopropionic acid-capped Mn-doped ZnS quantum dots/ethidium bromide (EB) nanohybrids were constructed for photoinduced electron transfer (PIET) and then used as a room-temperature phosphorescence (RTP) probe for DNA detection. EB could quench the RTP of Mn-doped ZnS QDs by PIET, thereby forming Mn-doped ZnS QDs/EB nanohybrids and storing RTP. Meanwhile, EB could be inserted into DNA and EB could be competitively desorbed from the surface of Mn-doped ZnS QDs by DNA, thereby releasing the RTP of Mn-doped ZnS QDs. Based on this mechanism, a RTP sensor for DNA detection was developed. Under optimal conditions, the detection limit for DNA was 0.045 mg L−1, the relative standard deviation was 1.7%, and the method linear ranged from 0.2 to 20 mg L−1. The proposed method was applied to biological fluids, in which satisfactory results were obtained.

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