Quantum dots and Au nanoparticles conjugated fluorescent DNA probes into uniform microstructure by asymmetrical synthesis

The fluorescent DNA probes using CdTe quantum dots (QDs) and Au nanoparticles (AuNPs) had complicated microstructures because one QD or AuNP can be conjugated to more than one single-stranded DNA (ssDNA) on its surface. In this Letter, an asymmetrical synthesis method of DNA probes was presented to get the DNA probes into the uniform microstructure when poly(N-isopropylacrylamide-co-divinylbenzene) microspheres (PNDMs) were used as templates. The sterically restricted linkages of CdTe QDs with ssDNA (CdTe-DNA₁) and AuNPs with complementary ssDNA (Au-DNA₂) were both present on PNDMs. After the CdTe-DNA₁ and Au-DNA₂ were cleaved from carriers and hybridised with each other, the fluorescent DNA probes (CdTe-dsDNA-Au) were prepared using 1 QD with 1 AuNP microstructure and the corresponding quenching efficiency of probes was 64.8%.