Synthesis and characterization of DNA-functionalized gold nanoparticles to detect lead ions

Lead contamination of drinking water is of great concern since it is toxic to human health and can result in various fatal diseases due to its high toxicity and bioaccumulation. Therefore, the detection of trace amounts of lead ions in water using a facile, straightforward, and sensitive home-based test is vitally important so as to monitor and prevent lead ion pollution. Gold nanoparticles are a well-developed technology that can produce visible color changes when conditions are changed. G-quadruplexes are 4-stranded DNA structures, which are known to strongly bind lead ions. Moreover, it is known that DNA oligonucleotides can be adsorbed onto gold nanoparticles via thiol-gold interactions. The goal of the research project is to make spherical nucleic acids (SNAs), which have gold nanoparticle cores with G-quadruplexes arranged to extend outwards from the surface of the gold nanoparticles. We then evaluated their physical and optical properties for detecting lead ions. We reported the progress in synthesis and characterization of the G-quadruplex SNA nanoparticles and the observations of their visible spectra in the presence of lead. This strategy has the potential to benefit society since people will be able to test water for lead easily in their own homes.