A simple and rapid colorimetric detection of Staphylococcus aureus relied on the distance-dependent optical properties of silver nanoparticles

• Published in: Analytical methods Vol. 16; no. 18; p. 2913
• Main Authors: Anh Thu, Phan Ngoc, Men, Nguyen Hoang, Thi Vo, Cam-Duyen, Van Toi, Vo, Truong, Phuoc Long
• Format: Journal Article
• Language: English
• Published: England 09-05-2024
• Subjects: Biosensing Techniques - methods; Colorimetry - methods; DNA, Bacterial - analysis; Humans; Limit of Detection; Metal Nanoparticles - chemistry; Silver - chemistry; Staphylococcus aureus - isolation & purification
• ISSN: 1759-9679
• DOI: 10.1039/d3ay02189k

The quick and accurate diagnosis of pathogens has appeared as a pressing issue in clinical diagnostics, environmental monitoring, and food safety. The available assays are suffering from limited capacities in simple, fast, low-cost, and on-site detection to increase prevention and proper treatment. Herein, we address these challenges by developing a simple, speedy, affordable, and ultrasensitive nanoplasmonic biosensor for colorimetric detection of cDNA from
RNA relying on the distance-dependent optical features of silver nanostructures for the measurement of color variations and spectral shifts owing to the plasmon coupling generated by the cross-linking accumulation of AgNPs. The method described utilizes silver nanoparticles (AgNPs) immobilized with two different single-stranded oligonucleotides (ssDNA
and ssDNA
) that specifically recognize the target DNA. Sandwich hybridization of target DNA with ssDNA
and ssDNA
induced color variations and spectral shifts of AgNPs, whereas test samples without the target DNA remained yellow as the initial color of colloidal silver. The designed nanoplasmonic biosensor demonstrated high specificity with the detection limit (LOD) of ∼1.8 amol target DNA (∼10
molecules per test) in the broad linear dynamic range from 0.01 to 100 nM, and LOD down to a few cells was attained for amplified bacterial nucleic acids and a linear range from 10
CFU mL
to 10
CFU mL
. The sensing approach showed great potential for the timely diagnosis of pathogens in low-density samples, and it has considerable merits over traditional culture approaches and qPCR techniques.