A Highly Sensitive Electrochemical Biosensor Based on Carbon Black and Gold Nanoparticles Modified Pencil Graphite Electrode for microRNA-21 Detection

Abstract

This work aims to develop cost-effective, simple and sensitive electrochemical biosensor for detection of microRNA-21. The combination of carbon black (CB) and gold nanoparticles (AuNPs) as nanohybrid was employed for the first time as a platform for microRNA-21 biosensor fabrication. The developed biosensor is based on the immobilization of thiolated capture probe (complementary sequence of microRNA-21) labeled with methylene blue on the surface of the pencil graphite electrode modified with CB/AuNPs nanohybrid. After hybridization with the target microRNA-21, the orientation of the labeled capture probe changed which causes a decrease of the response of methylene blue oxidation. Differential pulse voltammetry was used for monitoring the methylene blue response before and after hybridization. Under the optimal conditions, the developed biosensor was characterized using differential pulse voltammetry (DPV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The detection of microRNA-21 was carried out using a DPV. A wide linear range was obtained between 2.9 fM and 0.7 µM of microRNA-21. The calculated limit of detection was 1 fM of microRNA-21. This approach shows a good reproducibility, stability and an excellent selectivity. The proposed biosensor was used for microRNA-21 analysis in serum and a satisfactory result was obtained.

Two-step formulation of magnetic nanoprobes for microRNA capture

“…The estimated number of CmiR molecules grafted per nanoprobe was 11, 22 and 20 for the samples NP–STR–CmiR1, NP–STR–CmiR5, and NP–STR–CmiR10 respectively. To the best of our knowledge, very few publications reported the quantity of grafted CmiR 31,32 or other oligonucleotides 27 per nanoprobe or even the concentration of grafted CmiR. 33,34 Although less explored in the literature, these values are important since they allow to evaluate both the conjugation method used and the expected efficiency of TmiR capture.…”

Electrochemical Biosensors for Detection of MicroRNA as a Cancer Biomarker: Pros and Cons

“…For example, metals such as gold nanoparticles [ 41 ], silver nanoparticles [ 42 ], cadmium [ 43 ], and plomb [ 44 ] were employed as an inorganic RedOx probe. Organic molecules including, thionine (Thi) [ 45 ], ferrocene (Fc) [ 46 ], and methylene blue (MB) [ 47 ] were mostly used. Indeed, the RedOx molecule could be labeled to the probe sequence directly or with the help of a linker.…”

“…This method allows an improvement of the LOD where 3.2 aM is demonstrated. Yammouri et al [ 47 ] demonstrated a biosensor for miRNA cancer markers with LOD of 1 fM using a basic design where MB-labeled DNA probe sequences and well adapted surface chemistry based on pencil carbon were used. This allows a signal of readout after DNA hybridization without using TCEP as a mediator.…”

Recent Applications of Carbon Nanomaterials for microRNA Electrochemical Sensing

“…For example, Yammouri et al prepared an economical, simple and sensitive electrochemical biosensor for miRNA-21 detection based on the nanocomplexes based on CB and AuNPs. [130] The biosensor used methylene blue (MB) to label mercapto capture probe (miRNA-21 complementary sequence). After hybridization with the target miRNA-21, the direction of the labeled capture probe changed, leading to a decrease in MB oxidation reaction.…”