Ionic Liquid Modified Single‐use Electrode Developed for Voltammetric Detection of miRNA‐34a and its Application to Real Samples

Advances in Electrochemical Biosensor Technologies for the Detection of Nucleic Acid Breast Cancer Biomarkers

Breast cancer is the second leading cause of cancer deaths in women worldwide; therefore, there is an increased need for the discovery, development, optimization, and quantification of diagnostic biomarkers that can improve the disease diagnosis, prognosis, and therapeutic outcome. Circulating cell-free nucleic acids biomarkers such as microRNAs (miRNAs) and breast cancer susceptibility gene 1 (BRCA1) allow the characterization of the genetic features and screening breast cancer patients. Electrochemical biosensors offer excellent platforms for the detection of breast cancer biomarkers due to their high sensitivity and selectivity, low cost, use of small analyte volumes, and easy miniaturization. In this context, this article provides an exhaustive review concerning the electrochemical methods of characterization and quantification of different miRNAs and BRCA1 breast cancer biomarkers using electrochemical DNA biosensors based on the detection of hybridization events between a DNA or peptide nucleic acid probe and the target nucleic acid sequence. The fabrication approaches, the biosensors architectures, the signal amplification strategies, the detection techniques, and the key performance parameters, such as the linearity range and the limit of detection, were discussed.

Diagnostic kit based on halloysite nanoclay-ionic liquid nanocomposite modified electrode for electrochemical determination of cancer biomarker

Nucleic acid hybridization is occurred between the selective single-stranded nucleic acid sequence and its target sequence, which is one of the essential procedure for electrochemical detection of nucleic acid. microRNA-21 (miRNA-21) is known as a biomarker in various cancers. The determination of miRNA-21 was attained through by hybridization of inosine substituted miRNA-21 specific DNA probe (P_inosine) with its target miRNA-21. In this study, the surface of pencil graphite electrode (PGE) was firstly modified with halloysite nanoclay-ionic liquid (HNT/IL) nanocomposite. The characterization of surface was performed by Scanning Electron Microscope (SEM) images and Energy Dispersive X-Ray Analysis (EDX) analysis, and the differences at surface modifications were also shown by electrochemical methods with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). For sensitive and selective determination of miRNA-21, P_inosine and target miRNA concentration, immobilization and hybridization time were optimized by using HNT/IL modified PGE in combination with differential pulse voltammetry (DPV). The detection limit was achieved as 0.17 μg/mL (equals to 23.69 nM) in the linear range of 0.25-2 μg/mL miRNA-21. The selectivity of voltammetric method based on HNT/IL-PGE developed for miRNA-21 was examined in the presence of mismatch (MM) and non-complementary (NC) sequences. Because miRNA-21 is over-expressed in cancer cells, it has been tested in total RNA samples isolated from cancer cell line (breast cancer cell line, MCF-7). In the total RNA samples obtained from MCF-7, the detection limit was calculated as 0.28 μg/mL in the linear range of 1-4 μg/mL. Besides, the healthy cell line (human embryonic kidney cell line, HEK-293) was used as a control group and the results obtained by MCF-7 total RNA samples were compared to the results using HEK-293 total RNA samples in terms of miRNA-21 level.

Zip Nucleic Acid-Based Genomagnetic Assay for Electrochemical Detection of microRNA-34a

Zip nucleic acid (ZNA)-based genomagnetic assay was developed herein for the electrochemical detection of microRNA-34a (miR-34a), which is related to neurological disorders and cancer. The hybridization between the ZNA probe and miR-34a target was performed in the solution phase; then, the resultant hybrids were immobilized onto the surface of magnetic beads (MBs). After magnetic separation, the hybrids were separated from the surface of MBs and then immobilized on the surface of pencil graphite electrodes (PGEs). In the case of a full-match hybridization, the guanine oxidation signal was measured via the differential pulse voltammetry (DPV) technique. All the experimental parameters that influenced the hybridization efficiency (i.e., hybridization strategy, probe concentration, hybridization temperature, etc.) were optimized. The cross-selectivity of the genomagnetic assay was tested against two different miRNAs, miR-155 and miR-181b, individually as well as in mixture samples. To show the applicability of the ZNA-based genomagnetic assay for miR-34a detection in real samples, a batch of experiments was carried out in this study by using the total RNA samples isolated from the human hepatocellular carcinoma cell line (HUH-7).

Graphene-Oxide and Ionic Liquid Modified Electrodes for Electrochemical Sensing of Breast Cancer 1 Gene

Graphene-oxide and ionic liquid composite-modified pencil graphite electrodes (GO-IL-PGEs) were developed and used as a sensing platform for breast cancer 1 (BRCA1) gene detection. The characterization of GO-IL modified electrodes was executed by scanning electron microscopy (SEM), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The nucleic-acid hybridization was monitored by a differential pulse voltammetry (DPV) technique by directly measuring the guanine oxidation signal without using any indicator. The effects of the IL concentration, the probe concentration, and the hybridization time were optimized to the biosensor response. The limit of detection (LOD) was calculated in the concentration range of 2–10 μg/mL for the BRCA1 gene and found to be 1.48 µg/mL. The sensitivity of the sensor was calculated as 1.49 µA mL/µg cm². The developed biosensor can effectively discriminate the complementary target sequence in comparison to a three-base-mismatched sequence or the non-complementary one.

Functional Ionic Liquids Decorated Carbon Hybrid Nanomaterials for the Electrochemical Biosensors

Ionic liquids are gaining high attention due to their extremely unique physiochemical properties and are being utilized in numerous applications in the field of electrochemistry and bio-nanotechnology. The excellent ionic conductivity and the wide electrochemical window open a new avenue in the construction of electrochemical devices. On the other hand, carbon nanomaterials, such as graphene (GR), graphene oxide (GO), carbon dots (CDs), and carbon nanotubes (CNTs), are highly utilized in electrochemical applications. Since they have a large surface area, high conductivity, stability, and functionality, they are promising in biosensor applications. Nevertheless, the combination of ionic liquids (ILs) and carbon nanomaterials (CNMs) results in the functional ILs-CNMs hybrid nanocomposites with considerably improved surface chemistry and electrochemical properties. Moreover, the high functionality and biocompatibility of ILs favor the high loading of biomolecules on the electrode surface. They extremely enhance the sensitivity of the biosensor that reaches the ability of ultra-low detection limit. This review aims to provide the studies of the synthesis, properties, and bonding of functional ILs-CNMs. Further, their electrochemical sensors and biosensor applications for the detection of numerous analytes are also discussed.

Evolution of nucleic acids biosensors detection limit III

This review is an update of two previous ones focusing on the limit of detection of electrochemical nucleic acid biosensors allowing direct detection of nucleic acid target (miRNA, mRNA, DNA) after hybridization event. A classification founded on the nature of the electrochemical transduction pathway is established. It provides an overall picture of the detection limit evolution of the various sensor architectures developed during the last three decades and a critical report of recent strategies.

Cobalt Phthalocyanine-Ionic Liquid Composite Modified Electrodes for the Voltammetric Detection of DNA Hybridization Related to Hepatitis B Virus

In this study, cobalt phthalocyanine (CoPc) and ionic liquid (IL) modified pencil graphite electrodes (PGEs) were designed and implemented to detect sequence-selective DNA hybridization related to the Hepatitis B virus (HBV). The surface characterization of CoPc-IL-PGEs was investigated by scanning electron microscopy (SEM), and the electrochemical behavior of electrodes were studied by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. The voltammetric detection of hybridization was investigated by evaluating the guanine oxidation signal, measured by differential pulse voltammetry (DPV) technique. The implementation of our biosensor to serum samples was also examined using fetal bovine serum (FBS). The detection limit was established as 0.19 µg/mL in phosphate buffer solution (PBS) (pH 7.40) and 2.48 µg/mL in FBS medium. The selectivity of our assay regarding HBV DNA hybridization in FBS medium was tested in the presence of other DNA sequences. With this aim, the hybridization of DNA probe with non-complementary (NC) or mismatched DNA sequence (MM), or in the presence of mixture samples containing DNA target NC (1:1) or DNA target MM (1:1), was studied based on the changes in guanine signal.

Recent trends in application of nanomaterials for the development of electrochemical microRNA biosensors

The biology of the late twentieth century was marked by the discovery in 1993 of a new class of small non-coding ribonucleic acids (RNAs) which play major roles in regulating the translation and degradation of messenger RNAs. These small RNAs (18-25 nucleotides), called microRNAs (miRNAs), are implied in several biological processes such as differentiation, metabolic homeostasis, or cellular apoptosis and proliferation. The discovery in 2008 that the presence of miRNAs in body fluids could be correlated with cancer (prostate, breast, colon, lung, etc.) or other diseases (diabetes, heart diseases, etc.) has made them new key players as biomarkers. Therefore, miRNA detection is of considerable significance in both disease diagnosis and in the study of miRNA function. Until these days, more than 1200 miRNAs have been identified. However, traditional methods developed for conventional DNA does not apply satisfactorily for miRNA, in particular due to the low expression level of these miRNA in biofluids, and because they are very short strands. Electrochemical biosensors can provide this sensitivity and also offer the advantages of mass fabrication, low-cost, and potential decentralized analysis, which has wide application for microRNAs sensing, with many promising results already reported. The present review summarizes some newly developed electrochemical miRNA detection methods.

Paper-based electrode assemble for impedimetric detection of miRNA

In the present work, a paper-based electrode assemble was developed and implemented to detect target microRNA 155 (miRNA 155) via electrochemical impedance spectroscopy (EIS) measurements. In this concept, gold nanoparticles (AuNPs) modified paper based electrode assemble system (AuNP-PE) was designed, and characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and EIS measurements. The impedimetric detection of miRNA 155 was performed by measuring the fractional change at the charge transfer resistance (R_ct). The detection limits were found as 33.8 nM in PBS and 93.4 nM in fetal bovine serum (FBS) medium, respectively. The selectivity of the proposed assay was tested against to non-complementary (NC) and mismatch (MM) miRNA sequences in the presence of mixture sample containing miRNA:NC (1:1) and miRNA:MM (1:1) in PBS (pH 7.40) or FBS. The analytical performance and the selectivity of impedimetric biosensor were also tested in FBS.

Voltammetric detection of miRNA hybridization based on electroactive indicator-cobalt phenanthroline

The indicator-based nucleic acid detection protocol is one of the major approaches to monitor the sequence-selective nucleic acid hybridization-mediated recognition events in biochemical analysis. The metal complex, cobalt phenanthroline, [Co(phen)33+], which is one of the electroactive indicators, interacts more with double stranded nucleic acids via intercalation. Thus, this interaction permits an increase at the electrochemical signal of [Co(phen)33+]. In our study, the interaction of metal complex, [Co(phen)33+] with nucleic acids was examined using pencil graphite electrodes (PGEs) in combination with differential pulse voltammetry (DPV) technique. The voltammetric detection of miRNA-34a was investigated based on the changes at the electrochemical signal of [Co(phen)33+] under optimized experimental conditions; such as accumulation potentialof metal complex and DNA probe concentration, hybridization time, target miRNA concentration. Furthermore, the selectivity of electrochemical miRNA-34a biosensor was studied in contrast to different miRNAs. The applicability of indicator-based biosensor specific to miRNA-34a was also presented by using total RNA samples.