Sensitive detection of glucose in human serum with oligonucleotide modified gold nanoparticles by using dynamic light scattering technique

Abstract

Dynamic light scattering based sensor for glucose was developed with oligonucleotide functionalized gold nanoparticles (Oligo-AuNPs). Oligonucleotide 5′-SH-(A)12-AGACAAGAGAGG-3′ (Oligo 1) modified AuNPs and oligonucleotide 5′-CAACAGAGAACG-(A)12-HS-3′ (Oligo 2) modified AuNPs could hybridize with oligonulceotide 5′-CGTTCTCTGTTGCCTCTCTTGTCT-3′ (Oligo 3), which resulted in the aggregation of Oligo-AuNPs probes, and triggered the increase of their average diameter. However, Oligo 3 could be cleaved into DNA fragments by the mixture of glucose, glucose oxidase (GOD) and Fe2+, and the DNA fragments could not hybridize with Oligo-AuNPs probes. Under the conditions of 3.7nM Oligo 1-AuNPs, 3.7nM Oligo 2-AuNPs, 8.0μg/mL GOD, 100nM Oligo 3 and 900nM Fe2+, the average diameter of Oligo-AuNPs probes decreased linearly with the increasing concentration of glucose over the range from 50pmol/L to 5.0nmol/L, with a detection limit of 38pmol/L (3σ/slope). Moreover, five sugars had no effect on the average diameter of mixture of Oligo-AuNPs probes, GOD and Fe2+, which demonstrated the good selectivity of the assay.