The authors describe a method for the colorimetric determination of unamplified microRNA. It is based on the use of citrate-capped gold nanoparticles (AuNPs) and, alternatively, a microRNA-probe hybrid or a magnetically extracted microRNA that serve as stabilizers against the salt-induced aggregation of AuNPs. The absorbance ratios A525/A625of the reacted AuNP solutions were used to quantify the amount of microRNA. The assay works in the range of 5-25 pmol microRNA. The lower limit of detection (LOD) is 10 pmol. The performance of the method was tested by detection of microRNA-210-3p in totally extracted urinary microRNA from normal, benign, and bladder cancer subjects. The sensitivity and specificity for qualitative detection of urinary microRNA-210-3p using the assay are 74% and 88% respectively, which is consistent with real time PCR based assays. The assay was applied to the determination of specific microRNA by using its specific oligo targeter or following magnetic isolation of the desired microRNA. The method is simple, cost-efficient, has a short turn-around time and requires minimal equipment and personnel. Graphical abstract Schematic of the two detection schemes: In the first approach, matched microRNA hybridizes with its specific probe to stabilize gold nanoparticles (AuNPs) against salt induced aggregation and to leave the red color of the AuNPs unchanged. In the second one, microRNA extracted via magnetic nanoparticles (MNP) stabilizes AuNPs against aggregation.
Mikrochimica acta. 2018 Mar 22*** epublish ***
Ahmed Ibrahim Nossier, Hana Abdelzaher, Marwa Matboli, Sanaa Eissa
Biochemistry Department, Faculty of Pharmacy, Misr University for Science and Technology (MUST), 6th October City, Giza, Egypt. ., Faculty of Biotechnology, October University for Modern Sciences & Arts, 6th October City, Cairo, Egypt., Oncology Diagnostic Unit, Medical Biochemistry & Molecular Biology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt., Oncology Diagnostic Unit, Medical Biochemistry & Molecular Biology Department, Faculty of Medicine, Ain Shams University, Cairo, Egypt. .