Introducing DNA Nanosensor to Undergraduate Students: Rapid Non-Cross-Linking Aggregation of DNA-Functionalized Gold Nanoparticles for Colorimetric DNA Assay

Abstract

Demonstration of a colorimetric approach for nucleic acid detection represents an attractive educational experiment for chemistry undergraduate students in the time of coronavirus pandemic. Herein, a rapid and vivid detection method that visualizes the presence of a specific DNA sequence is described. The plasmon resonance of gold nanoparticles (AuNPs) (∼20 nm in diameter) endows a red color to DNA-functionalized gold nanoparticles (DNA-AuNPs) in a colloidal solution. Simply upon addition of a sample containing the complementary DNA sequence, the DNA-AuNPs dispersed in a strong ionic solution can spontaneously aggregate in minutes and turn to be purple in color, which can be detected using UV–visible spectroscopy as well as the naked eye. In contrast, the DNA-AuNPs remain highly dispersed as a reddish colloid even at high ionic strength when the DNA sequence is terminally mismatched or overhung. According to the teaching experience, this DNA testing experiment can be accomplished by students in pairs or groups under instruction in a three-day lab session. Given the rapid and fail-proof DNA testing, the testing method is also well-suited for hands-on introduction of analytical chemistry and nanotechnology to chemistry freshman and high school students.

Improved Gold Nanoprobes for Detection of Single Nucleotide Polymorphisms: The Influence of Size

“…Functionalization of AuNPs with thiol-modified oligonucleotides has been the subject of several studies. In order to optimize the degree of functionalization and the availability of the DNA bases for hybridization, two methods based on the decrease of the electrostatic repulsion between oligonucleotides have been proposed: i) the salt aging (SA) method, [8,[22][23][24] and the pH method. [20,21,25] In both methods, the neutralization of oligonucleotide charge with the consequent decrease in surface charge of the functionalized nanoprobes, can lead to partial aggregation.…”

DNA-Functionalized Silver Nanoparticles in an Alcoholic Solvent for Environment-Dictated Multimodal Actuation

“…The concentration of the AgNPs was calculated using an extinction coefficient of 41.8 × 10 8 M −1 cm −1 . 29 Prior to DNA modification of the AgNPs based on a documented protocol, 30,31 mercaptohexyl DNA (HS-DNA) was reduced by TCEP to cleave the disulfide bond and then purified by ethanol precipitation (see the sequence information in Table S1). The AgNPs were first mixed with bis(p-sulfonatophenyl)phenylphosphine dihydrate dipotassium salt (BSPP, 20 mg mL −1 ) to give a final concentration of 1 mg mL −1 , followed by incubation overnight and removal of excess BSPP by centrifugation.…”

Why Is There a Red Line? A High School Experiment to Model the Role of Gold Nanoparticles in Lateral Flow Assays for COVID-19

“…43 ■ DEVELOPMENT OF THE LFA MODEL Experiments on antigen−antibody interactions have already been conducted in the context of enzyme-linked immunosorbent assays (ELISA) at both the university 45,46 and the high school level. 47,48 He et al 49 presented DNA-functionalized nanoparticles that can be used as nanosensors; Roupioz 50 used gold nanoparticles for the detection of adenosine. Recently, Kantor et al 51 employed LFAs in a laboratory setting for undergraduates to investigate analytical concepts such as specificity and sensitivity.…”