A Colorimetric Lead Biosensor Using DNAzyme-Directed Assembly of Gold Nanoparticles

Abstract

A highly sensitive and selective colorimetric lead biosensor based on DNAzyme-directed assembly of gold nanoparticles is reported. It consists of a DNAzyme and its substrate that can hybridize to a 5'-thio-modified DNA attached to gold nanoparticles. The hybridization brings gold nanoparticles together, resulting in a blue-colored nanoparticle assembly. In the presence of lead, the DNAzyme catalyzes specific hydrolytic cleavage, which prevents the formation of the nanoparticle assembly, resulting in red-colored individual nanoparticles. The detection level can be tuned to several orders of magnitude, from 100 nM to over 200 muM, through addition of an inactive variant of the DNAzyme. The concept developed here can be applied to the design of nucleic acid enzyme/nanoparticle sensors for analytes that are subject to in vitro selection, and thus can significantly expand the scope of nanomaterial applications and provide a novel approach to designing simple colorimetric biosensors.

Characterization of glucose oxidation by gold nanoparticles using nanoceria

“…For subsequent quantitative studies, the ratio of absorbance at 400 nm over 290 nm was used to quantify the color change and thus of the amount of hydrogen peroxide produced in a sample. Such ratiometric methods are convenient for quantification and have been used to quantify the color change of AuNPs [28]. Using nanoceria to detect H2O2 is highly sensitive [22], and in our system we can easily detect 3 parts-per-million H2O2 ( Figure S2).…”

Sensing Parts-per-Trillion Cd2+, Hg2+, and Pb2+ Collectively and Individually Using Phosphorothioate DNAzymes

“…[12][13][14][15][16] Owing to their high catalytic efficiency and versatility in sensor design, RNA-cleaving DNAzymes have emerged as a unique metal sensing platform. 14,[17][18][19][20][21] Since DNAzymes require metal cofactors, by using specific metals during selection, RNA-cleaving DNAzymes selective for Mg 2+ , 13 Pb 2+ , 22,23 UO2 2+24 and lanthanides 25 have been reported. These metals are hard or borderline Lewis acids.…”

Incorporation of the fluoride induced SiO bond cleavage and functionalized gold nanoparticle aggregation into one colorimetric probe for highly specific and sensitive detection of fluoride

“…Various metal ions were detected by monitoring the color changes occurring upon aggregation of ligand-functionalized AuNPs through specific molecular interactions [26][27][28][29][30]. However, studies on colorimetric anion recognition and sensing anions by AuNPs are limited [31][32][33][34][35][36].…”