A quantification strategy for DNA hybridization via measurement of adsorbed anthraquinone monosulphonic acid on silica nanospheres

Abstract An amperometric DNA biosensor was developed based on a DNA quantification concept involving the adsorption behavior of anthraquinone monosulphonic acid (AQMS). The biosensor was built from a carbon pasted screen-printed electrode coated with silica nanospheres and gold nanoparticles. Silica nanospheres of 65–84 nm were synthesized via sonication and its surface further modified with amine group. Aminated silica nanospheres immobilize amine-functionalized DNA probe covalently via glutaraldehyde linkers while gold nanoparticles used as an effective electron transfer agent. Anionic AQMS can physically adsorb onto cationic aminated silica nanospheres, and the total AQMS adsorption will be reduced if hybridization occurs. Hence, an increasing amount of hybridized DNA cause a declination in differential pulse voltammetric current signal of AQMS at −0.50 V. The biosensor yielded a linear response range of 10 −9 –0.5 μM (R 2  = 0.97) towards DNA target and showed negligible response to mismatched and noncomplemetary DNA. The fabricated DNA biosensor as an early detection and possible noninvasive method for clinical and medical use was successfully performed; with the detection of synthetic DNA target and cDNA that were reverse-transcripted from dengue virus RNA.