Preparation of fluorescent DNA probe by solid-phase organic synthesis

Fluorescent DNA probe based on fluorescence resonance energy transfer (FRET) was prepared by solid-phase organic synthesis when CdTe quantum dots (QDs) were as energy donors and Au nanoparticles (AuNPs) were as energy accepters. The poly(divinylbenzene) core/poly(4-vinylpyridine) shell microspheres, as solid-phase carriers, were prepared by seeds distillation-precipitation polymerization with 2,2′-azobisisobutyronitrile (AIBN) as initiator in neat acetonitrile. The CdTe QDs and AuNPs were self-assembled on the surface of core/shell microspheres, and then the linkage of CdTe QDs with oligonucleotides (CdTe-DNA) and AuNPs with complementary single-stranded DNA (Au-DNA) was on the solid-phase carriers instead of in aqueous solution. The hybridization of complementary double stranded DNA (dsDNA) bonded to the QDs and AuNPs (CdTe-dsDNA-Au) determined the FRET distance of CdTe QDs and AuNPs. Compared with the fluorescence of CdTe-DNA, the fluorescence of CdTe-dsDNA-Au conjugates (DNA probes) decreased extremely, which indicated that the FRET occurred between CdTe QDs and AuNPs. The probe system would have a certain degree recovery of fluorescence when the complementary single stranded DNA was introduced into this system, which showed that the distance between CdTe QDs and AuNPs was increased.