OBJECTIVETo investigate the specificity of the dual-functionalized nanoparticles probes (NPs) self-assembled with colloidal gold.

METHODS13-nm gold nanoparticles were prepared with citrate reduction of HAuCl(4). These gold nanoparticles were sequentially functionalized with the specific single-strand oligonucleotide of HA gene of influenza A virus (H1N1) and disulfide molecules of m/z at 693. The NPs solution showed the red formation. The magnetic microparticles (MPs) were modified with another specific single-strand oligonucleotide in HA gene of H1N1. The sandwich complexes (MP-Target-NPs) were formed by the target DNA with the MPs and the NPs. The color change in the solution was observed and the dehybridization product was detected by MALDI TOF MS. Moreover specificity of the probes was investigated with nano-water (as a blank control) and the different target DNAs including complementary DNA,non-complementary DNA and two DNAs of one base mismatch, respectively.

RESULTThe red formation and the positive signal in MS detection of reporter mass code 693 ([M+Na](+)) were observed,which indicated the formation of sandwich complexes formed only when the completely complementary target DNAs were presented in the solution. No color formation changes and no peak signal detected by MALDI TOF MS were observed,showing that none of target of interest (nano-pure water),non-complementary DNA and two DNAs of one base mismatch existed in the systems,which indicated no sandwich complexes formed between the target DNAs and the two probes.

CONCLUSIONConsidering the simple preparation procedure and high specificity,the dual-functionalized gold nanoparticle probes would be widely and increasingly used in nucleic acid analysis. In particular,it would have broad application prospects in early diagnosis of diseases,single nucleotide polymorphism (SNP) typing and so on.