Publication date: 28th June 2024
Immobilization of DNA on gold nanoparticles (GNPs) is an important consideration in electrochemical biosensing. Non-covalent immobilization of DNA on GNPs utilizes the intrinsic affinity of DNA bases to GNPs and provides a simple and convenient method of immobilization, thereby circumventing the time-consuming and costly techniques for DNA labelling or functionalized electrode preparation for DNA conjugation [1]. Researchers have reported the use of non-covalent adsorption of DNA on metallic electrode surfaces for electrochemical biosensing, but the mechanism of binding has not been much explored [1, 2]. In this study, we propose how different non-covalent DNA immobilization conditions alter the conformation of oligonucleotides on gold nanoparticles. We conduct a fundamental study for the adsorption of short model oligonucleotides onto gold nanoparticles (GNPs). It is observed that the variation in solution conditions has a profound effect on the way in which oligonucleotides bind to GNPs. We hypothesize the binding phenomena to be a contribution of several factors: base composition, strand directionality, competition of oligonucleotides to bind to GNPs or undergo inter-strand assembly, among others. In addition to these factors, the properties of the individual bases in the given solution conditions (such as protonation or deprotonation) also affect the way in which the oligonucleotide strand binds to GNPs. We foresee using this understanding to be helpful in the development of biosensors utilizing nucleotide conjugated nanoparticles as sensing elements.
References:
[1] Yang, Y., Li, C., Yin, L., Liu, M., Wang, Z., Shu, Y., & Li, G. (2014). Enhanced charge transfer by gold nanoparticle at DNA modified electrode and its application to label-free DNA detection. ACS applied materials & interfaces, 6(10), 7579-7584.
[2] Zhang, Q., & Subramanian, V. (2007). DNA hybridization detection with organic thin film transistors: Toward fast and disposable DNA microarray chips. Biosensors and Bioelectronics, 22(12), 3182-3187.
This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement No 865819). We acknowledge the financial contribution of the financial contribution of the “Progetto Dipartimento di Eccellenza” for providing the TEM facility.