Colorimetric detection of Hepatitis B virus based on sandwich assay hybridization using gold nano-particles

Nano-science made a significant impact on different scientific disciplines. Bio-molecular detection with DNA- and protein-functionalized gold nanoparticles are promising analytical assays. Back to 1996, use of oligonucleotide functionalized AuNPs for specific DNA sequence analysis was introduced by Mirikin [1].Gold nano-particles have several advantages over conventional detection methods (e.g. RT-PCR, ELISAs). Higher sensitivity, selectivity for target sequences, capacity for massive multiplexing, time efficiency, and ability to be performed at the point of care are it’s advantages [2,3]. Hepatitis B virus (HBV) infection is one of the major health problems worldwide, and may lead to chronichepatitis, cirrhosis and primary liver cancer. It is estimated that there are 2 billion people with a serological profile of past or current HBV infection [4]. Hence, it has a primary important to detect and monitor HBV at an early stage of the infection. In this Contribution, a novel nanobio-transducer was designed to detect HBV as a target biomolecules in a single step (without washing or separation) which summarized as: 1) AuNPs citrate capped with average diameter of 13 nm was synthesized. 2) Probe was designed and purchased [takapouzist company] based on cross-linking between two different Au-nanoprobes such that each was functionalized with a DNA-oligonucleotide complementary to one half of the given target. 3) Alkanethiol modified oligonucleotide was bound with Au nano-particles, through covalent binding of Au-S. 4) The hybridization of the two nano-probes with the target resulted in the formation of a polymeric network, which brought the gold nano-particles close enough to result in a red to blue color change. 5) Calibration curve was prepared for different concentration of target and appropriate result was achieved.