Indicator-free electrochemical biosensor for microRNA detection based on carbon nanofibers modified screen printed electrodes

Recent advances in isolation and detection of exosomal microRNAs related to Alzheimer's disease

Alzheimer's disease, a progressive neurological condition, is associated with various internal and external risk factors in the disease's early stages. Early diagnosis of Alzheimer's disease is essential for treatment management. Circulating exosomal microRNAs could be a new class of valuable biomarkers for early Alzheimer's disease diagnosis. Different kinds of biosensors have been introduced in recent years for the detection of these valuable biomarkers. Isolation of the exosomes is a crucial step in the detection process which is traditionally carried out by multi-step ultrafiltration. Microfluidics has improved the efficiency and costs of exosome isolation by implementing various effects and forces on the nano and microparticles in the microchannels. This paper reviews recent advancements in detecting Alzheimer's disease related exosomal microRNAs based on methods such as electrochemical, fluorescent, and SPR. The presented devices' pros and cons and their efficiencies compared with the gold standard methods are reported. Moreover, the application of microfluidic devices to detect Alzheimer's disease related biomarkers is summarized and presented. Finally, some challenges with the performance of novel technologies for isolating and detecting exosomal microRNAs are addressed.

Nanotechnology-Assisted Biosensors for the Detection of Viral Nucleic Acids: An Overview

The accurate and rapid diagnosis of viral diseases has garnered increasing attention in the field of biosensors. The development of highly sensitive, selective, and accessible biosensors is crucial for early disease detection and preventing mortality. However, developing biosensors optimized for viral disease diagnosis has several limitations, including the accurate detection of mutations. For decades, nanotechnology has been applied in numerous biological fields such as biosensors, bioelectronics, and regenerative medicine. Nanotechnology offers a promising strategy to address the current limitations of conventional viral nucleic acid-based biosensors. The implementation of nanotechnologies, such as functional nanomaterials, nanoplatform-fabrication techniques, and surface nanoengineering, to biosensors has not only improved the performance of biosensors but has also expanded the range of sensing targets. Therefore, a deep understanding of the combination of nanotechnologies and biosensors is required to prepare for sanitary emergencies such as the recent COVID-19 pandemic. In this review, we provide interdisciplinary information on nanotechnology-assisted biosensors. First, representative nanotechnologies for biosensors are discussed, after which this review summarizes various nanotechnology-assisted viral nucleic acid biosensors. Therefore, we expect that this review will provide a valuable basis for the development of novel viral nucleic acid biosensors.

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.

A review of highly sensitive electrochemical genosensors for microRNA detection: A novel diagnostic platform for neurodegenerative diseases diagnostics

The significant role of microRNAs in regulating gene expression and in disease tracking has handed the possibility of robust and accurate diagnosis of various diseases. Measurement of these biomarkers has also had a significant impact on the preparation of natural samples. Discovery of miRNAs is a major challenge due to their small size in the real sample and their short length, which is generally measured by complex and expensive methods. Electrochemical nanobiosensors have made significant progress in this field. Due to the delicate nature of nerve tissue repair and the significance of rapid-fire feature of neurodegenerative conditions, these biosensors can be reliably promising. This review presents advances in the field of neurodegenerative diseases diagnostics. At the same time, there are still numerous openings in this field that are a bright prospect for researchers in the rapid-fire opinion of neurological diseases and indeed nerve tissue repair.

Designed Mini Protein 20 Mimicking Uricase Encapsulated in ZIF-8 as Nanozyme Biosensor for Uric Acid Detection

This work presents the use of encapsulated mini protein 20 mimicking uricase (mp20)-zeolitic imidazolate framework-8 (ZIF-8) as a bioreceptor for the development of a nanozyme-based electrochemical biosensor for uric acid detection. The electrochemical performance of the biofunctionalized mp20@ZIF-8 on the reduced graphene oxide/screen-printed carbon electrode (rGO/SPCE) was investigated by optimizing operating parameters such as pH, deposition potential, and deposition time using a central composite design-response surface methodology (CCD-RSM). The quadratic regression model was developed to correlate the combination of each variable to the oxidation current density as a response. A significant effect on current response was observed under optimized conditions of pH of 7.4 at −0.35 V deposition potential and 56.56 s deposition time, with p < 0.05 for each interacted factor. The obtained coefficient of determination (R2) value of 0.9992 indicated good agreement with the experimental finding. The developed nanozyme biosensor (mp20@ZIF-8/rGO/SPCE) exhibited high selectivity in the presence of the same fold concentration of interfering species with a detection limit of 0.27 μM, over a concentration range of 1 to 34 μM. The practicality of the tailored biosensor in monitoring uric acid in human serum and urine samples was validated with high-performance liquid chromatography (HPLC) and a commercial uric acid meter. Hence, nanozyme-based is a promising platform that offers a rapid, sensitive, selective, and low-cost biosensor for the non-enzymatic detection of uric acid in biological samples.

Carbon Nanomaterial-Based Drug Sensing Platforms Using State-of-the- Art Electroanalytical Techniques

Background:

Currently, nanotechnology and nanomaterials are considered as the most popular and outstanding research subjects in scientific fields ranging from environmental studies to drug analysis. Carbon nanomaterials such as carbon nanotubes, graphene, carbon nanofibers etc. and non-carbon nanomaterials such as quantum dots, metal nanoparticles, nanorods etc. are widely used in electrochemical drug analysis for sensor development. Main aim of drug analysis with sensors is developing fast, easy to use and sensitive methods. Electroanalytical techniques such as voltammetry, potentiometry, amperometry etc. which measure electrical parameters such as current or potential in an electrochemical cell are considered economical, highly sensitive and versatile techniques.

Methods:

Most recent researches and studies about electrochemical analysis of drugs with carbon-based nanomaterials were analyzed. Books and review articles about this topic were reviewed.

Results:

The most significant carbon-based nanomaterials and electroanalytical techniques were explained in detail. In addition to this; recent applications of electrochemical techniques with carbon nanomaterials in drug analysis was expressed comprehensively. Recent researches about electrochemical applications of carbon-based nanomaterials in drug sensing were given in a table.

Conclusion:

Nanotechnology provides opportunities to create functional materials, devices and systems using nanomaterials with advantageous features such as high surface area, improved electrode kinetics and higher catalytic activity. Electrochemistry is widely used in drug analysis for pharmaceutical and medical purposes. Carbon nanomaterials based electrochemical sensors are one of the most preferred methods for drug analysis with high sensitivity, low cost and rapid detection.

Nanotechnology in emerging liquid biopsy applications

Liquid biopsy is considered as the most attractive alternative to traditional tissue biopsies. The major advantages of this approach lie in the non-invasive procedure, the rapidness of sample collection and the potential for early cancer diagnosis and real-time monitoring of the disease and the treatment response. Nanotechnology has dynamically emerged in a wide range of applications in the field of liquid biopsy. The benefits of using nanomaterials for biosensing include high sensitivity and detectability, simplicity in many cases, rapid analysis, the low cost of the analysis and the potential for portability and personalized medicine. The present paper reports on the nanomaterial-based methods and biosensors that have been developed for liquid biopsy applications. Most of the nanomaterials used exhibit great analytical performance; moreover, extremely low limits of detection have been achieved for all studied targets. This review will provide scientists with a comprehensive overview of all the nanomaterials and techniques that have been developed for liquid biopsy applications. A comparison of the developed methods in terms of detectability, dynamic range, time-length of the analysis and multiplicity, is also provided.

Nanoconstructs as a versatile tool for detection and diagnosis of Alzheimer biomarkers

The current review focuses towards the advancements made in the past decade in the field of nanotechnology for the early Alzheimer's disease (AD) diagnosis. This review includes the application of nanomaterials and nanosensors for the early detection of the main AD biomarkers (amyloid beta, phosphorylated tau, apolipoprotein E4 allele or APOE4, microRNAs, cholesterol, hydrogen peroxide etc) in biological fluids, to detect the biomarkers at a very low concentration ranging in pico, femto and even atto molar concentrations. The field of drug development has always aimed and is constantly working on developing disease modifying drugs, but these drugs will only succeed when given in the early disease stages. Thus, developing efficient diagnostic tools is of vital importance. Various nanomaterials such as liposomes; dendrimers; polymeric nanoparticles; coordination polymers; inorganic nanoparticles such as silica, manganese oxide, zinc oxide, iron oxide, super paramagnetic iron oxides; quantum dots, silver nanoparticles, gold nanoparticles, and carbon based nanostructures (carbon nanotubes, graphene oxide, nanofibres, nanodiamonds, carbon dots); Up-conversion nanoparticles; 2D nanomaterials; and radioactive nanoprobes have been used in constructing and improving efficiency of nano-sensors for AD biosensing at an early stage of diagnosis.

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.

Impedimetric Sensing of Factor V Leiden Mutation by Zip Nucleic Acid Probe and Electrochemical Array

A carbon nanofiber enriched 8-channel screen-printed electrochemical array was used for the impedimetric detection of SNP related to Factor V Leiden (FV Leiden) mutation, which is the most common inherited form of thrombophilia. FV Leiden mutation sensing was carried out in three steps: solution-phase nucleic acid hybridization between zip nucleic acid probe (Z-probe) and mutant type DNA target, followed by the immobilization of the hybrid on the working electrode area of array, and measurement by electrochemical impedance spectroscopy (EIS). The selectivity of the assay was tested against mutation-free DNA sequences and synthetic polymerase chain reaction (PCR) samples. The developed biosensor was a trustful assay for FV Leiden mutation diagnosis, which can effectively discriminate wild type and mutant type even in PCR samples.

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.

Electrochemical Detection of Solution Phase Hybridization Related to Single Nucleotide Mutation by Carbon Nanofibers Enriched Electrodes

In the present study, a sensitive and selective impedimetric detection of solution-phase nucleic acid hybridization related to Factor V Leiden (FV Leiden) mutation was performed by carbon nanofibers (CNF) modified screen printed electrodes (SPE). The microscopic and electrochemical characterization of CNF-SPEs was explored in comparison to the unmodified electrodes. Since the FV Leiden mutation is a widespread inherited risk factor predisposing to venous thromboembolism, this study herein aimed to perform the impedimetric detection of FV Leiden mutation by a zip nucleic acid (ZNA) probe-based assay in combination with CNF-SPEs. The selectivity of the assay was then examined against the mutation-free DNA sequences as well as the synthetic PCR samples.

Aligned polyvinylpyrrolidone nanofibers with advanced electrospinning for biomedical applications

BACKGROUND

Electrospinning is a highly effective method in order to generate nano-scaled fibers. In conventional electrospinning technique, geometry of nanofibers are mostly random due to the chaotic behavior of polymer jet.

OBJECTIVE

Purpose of this study is to produce aligned nanofibers from PVP polymers with advanced electrospinning technique in order to be used in a potential novel sensor applications, tissue regeneration and engineering.

METHODS

In this study, by using finite hollow cylinder focusing electrodes, an external electrostatic field is created. With these electrodes, it is aimed to decrease whipping instability of polymer jet. In addition, it is also investigated that the alignment ratio of nanofibers by using conductive parallel electrodes which placed through jet trajectory.

RESULTS

In conclusion, with the effect of electrical field created by cylinder electrodes, radius of the fiber dispersion on the collector was able to be reduced and aligned nanofibers were successfully produced by using electrical field generated from the parallel plates.

CONCLUSIONS

Radius of the fiber dispersion on the collector is 9.95 mm and fiber diameters varied between 800 nm and 3 μm. Additionally, alignment ratio of the fibers is determined with ImageJ software. These alignment of nanofibers can be used in tissue engineering applications and sensor applications.

An Impedimetric Biosensor Based on Ionic Liquid-Modified Graphite Electrodes Developed for microRNA-34a Detection

In the present work, an impedimetric nucleic acid biosensor has been designed for the purpose of detection of microRNA (miRNA). Ionic liquid (1-butyl-3-methylimidazolium hexafluorophosphate (IL))-modified chemically activated pencil graphite electrodes (PGEs) were used for the sensitive and selective detection of miRNA-34a. After covalent activation of the PGE surface using covalent agents (CAs), the ionic liquid (IL) was immobilized onto the surface of the chemically activated PGE by passive adsorption. The electrochemical and microscopic characterization of the IL/CA/PGEs was performed by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and scanning electron microscopy (SEM). DNA probe concentration, miRNA target concentration, and also the hybridization time and wet adsorption time were optimized by using the EIS technique. Then, the hybridization occurred between specific DNA probes and miRNA-34a was immobilized onto the surface of the IL/CA/PGEs. The impedimetric detection of miRNA-DNA hybrid was performed by EIS. The detection limit (DL) was calculated in a linear concentration range of 2⁻10 µg/mL miRNA-34a target, and it was found to be 0.772 µg/mL (109 nM) in phosphate buffer solution (PBS) and 0.826 µg/mL (117 nM) in diluted fetal bovine serum (FBS). The selectivity of impedimetric biosensor for miRNA-34a was also tested against to other non-complementary miRNA sequences both in buffer media, or diluted FBS.

Early detection of Alzheimer's disease using a biosensor based on electrochemically-reduced graphene oxide and gold nanowires for the quantification of serum microRNA-137

Serum miR-137 is quantified for the early detection of Alzheimer's disease using a electrochemically reduced graphene oxide and gold nanowire modified electrode.