Simultaneous detection of two breast cancer-related miRNAs in tumor tissues using p19-based disposable amperometric magnetobiosensing platforms

Advanced Approaches to Breast Cancer Classification and Diagnosis

The International Agency for Research on Cancer (IARC) has recently reported a 66% increase in the global number of cancer deaths since 1960. In the US alone, about one in eight women is expected to develop invasive breast cancer(s) (breast cancer) at some point in their lifetime. Traditionally, a BC diagnosis includes mammography, ultrasound, and some high-end molecular bioimaging. Unfortunately, these techniques detect BC at a later stage. So early and advanced molecular diagnostic tools are still in demand. In the past decade, various histological and immuno-molecular studies have demonstrated that BC is highly heterogeneous in nature. Its growth pattern, cytological features, and expression of key biomarkers in BC cells including hormonal receptor markers can be utilized to develop advanced diagnostic and therapeutic tools. A cancer cell's progression to malignancy exhibits various vital biomarkers, many of which are still underrepresented in BC diagnosis and treatment. Advances in genetics have also enabled the development of multigene assays to detect genetic heterogeneity in BC. However, thus far, the FDA has approved only four such biomarkers-cancer antigens (CA); CA 15-3, CA 27-29, Human epidermal growth factor receptor 2 (HER2), and circulating tumor cells (CTC) in assessing BC in body fluids. An adequately structured portable-biosensor with its non-invasive and inexpensive point-of-care analysis can quickly detect such biomarkers without significantly compromising its specificity and selectivity. Such advanced techniques are likely to discriminate between BC and a healthy patient by accurately measuring the cell shape, structure, depth, intracellular and extracellular environment, and lipid membrane compositions. Presently, BC treatments include surgery and systemic chemo- and targeted radiation therapy. A biopsied sample is then subjected to various multigene assays to predict the heterogeneity and recurrence score, thus guiding a specific treatment by providing complete information on the BC subtype involved. Thus far, we have seven prognostic multigene signature tests for BC providing a risk profile that can avoid unnecessary treatments in low-risk patients. Many comparative studies on multigene analysis projected the importance of integrating clinicopathological information with genomic-imprint analysis. Current cohort studies such as MINDACT, TAILORx, Trans-aTTOM, and many more, are likely to provide positive impact on long-term patient outcome. This review offers consolidated information on currently available BC diagnosis and treatment options. It further describes advanced biomarkers for the development of state-of-the-art early screening and diagnostic technologies.

Multiplex bioassaying of cancer proteins and biomacromolecules: Nanotechnological, structural and technical perspectives

Since the specific proteins (carbohydrate antigens, ligands and interleukins) get raised up in body tissue or fluids in cancer cases, early detection of them will provide an effective treatment and survival rate. Sensitive and accurate determination of multiple cancer proteins can be engaged in chorus by simultaneous/multiplex detection in the biomedical fields. Bioassaying technology is one of the non-invasive, high-sensitive, and economical methods. Currently, extensive application of nanomaterial (biocompatible polymers, metallic and metal oxide) in bioassays resulted in ultra-high sensitive and selective diagnosis. This review article focuses on types of multiplex bioassays for delicate and specific determination of cancer proteins for diagnostic aims. It also covers two modes of multiplex bioassays as multi labeled bioassays and spatially-separated test zones (multi-electrode mode). In this review, the nanotechnological, structural, and technical perspectives in the multiplex analysis of cancer proteins were discussed. Finally, the use of different types of nanomaterials, polysaccharides, biopolymers and their advantages in signal amplification are discussed.

QCM sensing of miR-21 by formation of microRNA-DNA hybrid duplexes and intercalation on surface-functionalized pyrene

MicroRNAs (miRNAs) are small non-coding RNA molecules that serve as important biomarkers for a variety of diseases such as cancer and vascular disease. However, sensitive and accurate detection of miR-21 is very challenging in that up-regulation of miR-21 is highly associated with several types of malignant tumors. Here, quartz crystal microbalance (QCM) biosensors were developed for sensitive and specific detection of miR-21 through formation of miR-21-DNA hybrid duplexes and non-specific intercalation of surface-modified pyrene molecules. High selectivity for miR-21 over other miRNAs came from the specific hybridization between miR-21 and gold nanoparticle (AuNP)-conjugated complementary oligonucleotides of miR-21. High sensitivity was obtained through formation of intercalated complexes on the surface with subsequent gold staining signal amplification. Under optimum condition using this strategic approach, our novel QCM biosensors could detect miR-21 concentration as low as 3.6 pM in the entire linear range from 2.5 pM to 2.5 μM with a correlation coefficient of 0.989. In addition, these sensors did not work at all for other miRNAs based on their high selectivity. miR-21 in human brain total RNA and total RNA extracted from A549 cell line could also be successfully detected. Therefore, miRNA detection technology using QCM biosensors and their detection mechanisms have potential as alternatives in biological studies and clinical diagnosis.

Multiplexed monitoring of a novel autoantibody diagnostic signature of colorectal cancer using HaloTag technology-based electrochemical immunosensing platform

Background and Purpose: The humoral immune response in cancer patients can be used for early detection of the disease. Autoantibodies raised against tumor-associated antigens (TAAs) are promising clinical biomarkers for reliable cancer diagnosis, prognosis, and therapy monitoring. In this study, an electrochemical disposable multiplexed immunosensing platform able to integrate difficult- and easy-to-express colorectal cancer (CRC) TAAs is reported for the sensitive determination of eight CRC-specific autoantibodies. Methods: The electrochemical immunosensing approach involves the use of magnetic microcarriers (MBs) as solid supports modified with covalently immobilized HaloTag fusion proteins for the selective capture of specific autoantibodies. After magnetic capture of the modified MBs onto screen-printed carbon working electrodes, the amperometric responses measured using the hydroquinone (HQ)/H2O2 system were related to the levels of autoantibodies in plasma. Results: The biosensing platform was applied to the analysis of autoantibodies against 8 TAAs described for the first time in this work in plasma samples from healthy asymptomatic individuals (n=3), and patients with high-risk of developing CRC (n=3), and from patients already diagnosed with colorectal (n=3), lung (n=2) or breast (n=2) cancer. The developed bioplatform demonstrated an improved discrimination between CRC patients and controls (asymptomatic healthy individuals and breast and lung cancer patients) compared to an ELISA-like luminescence test. Conclusions: The proposed methodology uses a just-in-time produced protein in a simpler protocol, with low sample volume, and involves cost-effective instrumentation, which could be used in a high-throughput manner for reliable population screening to facilitate the detection of early CRC patients at affordable cost.

11PS04 is a new chemical entity identified by microRNA-based biosensing with promising therapeutic potential against cancer stem cells

Phenotypic drug discovery must take advantage of the large amount of clinical data currently available. In this sense, the impact of microRNAs (miRs) on human disease and clinical therapeutic responses is becoming increasingly well documented. Accordingly, it might be possible to use miR-based signatures as phenotypic read-outs of pathological status, for example in cancer. Here, we propose to use the information accumulating regarding the biology of miRs from clinical research in the preclinical arena, adapting it to the use of miR biosensors in the earliest steps of drug screening. Thus, we have used an amperometric dual magnetosensor capable of monitoring a miR-21/miR-205 signature to screen for new drugs that restore these miRs to non-tumorigenic levels in cell models of breast cancer and glioblastoma. In this way we have been able to identify a new chemical entity, 11PS04 ((3aR,7aS)-2-(3-propoxyphenyl)-7,7a-dihydro-3aH-pyrano[3,4-d]oxazol-6(4H)-one), the therapeutic potential of which was suggested in mechanistic assays of disease models, including 3D cell culture (oncospheres) and xenografts. These assays highlighted the potential of this compound to attack cancer stem cells, reducing the growth of breast and glioblastoma tumors in vivo. These data demonstrate the enhanced chain of translatability of this strategy, opening up new perspectives for drug-discovery pipelines and highlighting the potential of miR-based electro-analytical sensors as efficient tools in modern drug discovery.

A facile deoxyuridine/biotin-modified molecular beacon for simultaneous detection of proteins and nucleic acids via a label-free and background-eliminated fluorescence assay

Simultaneous detection of different types of cancer biomarkers (nucleic acids and proteins) could facilitate early diagnosis of cancer and clinical treatment. Herein, a simultaneous detection platform of proteins and nucleic acids has been developed using a single substrate probe combining a label-free and background-eliminated fluorescence assay. Telomerase and telomerase RNA (TR) were chosen as the models. The molecular beacon (dU-BIO-HP) that contains deoxyuridine/biotin in its side arm, a TR recognition sequence in the loop and a telomerase substrate primer at the stem end was ingeniously designed. In the presence of telomerase, the stem of dU-BIO-HP is elongated by the addition of telomere repeats complementary to the assistant DNA. Furthermore, the formed dsDNA performed as engaging primers to initiate a SDA reaction, generating abundant G-quadruplex monomers. Similarly, on TR, the hybridization between TR and dU-BIO-HP can open its stem, triggering another SDA reaction, producing abundant short ssDNAs. With the G-quadruplex binding with ZnPPIX and ssDNA binding with SG for specific fluorescence responses, the label-free multiple detection can be achieved. In our strategy, the deoxyuridine of dU-BIO-HP acts as a barrier to block the DNA extension due to its strong inhibitory effects on DNA polymerase activity and to make sure that the two SDA reactions occurred independently. The biotin of dU-BIO-HP enables the reduction of the background from the binding between SG, ZnPPIX and dU-BIO-HP through streptavidin-biotin interaction. This method showed an excellent sensitivity with telomerase and TR detection limit of 2.18 HeLa cells per mL and 0.16 × 10^-12 M, respectively. Furthermore, the telomerase and TR in different cell lines have been evaluated as powerful tools for biomedical research and clinical diagnosis.

Pushing the limits of electrochemistry toward challenging applications in clinical diagnosis, prognosis, and therapeutic action

Constant progress in the identification of biomarkers at different molecular levels in samples of different natures, and the need to conduct routine analyses, even in limited-resource settings involving simple and short protocols, are examples of the growing current clinical demands not satisfied by conventional available techniques. In this context, the unique features offered by electrochemical biosensors, including affordability, real-time and reagentless monitoring, simple handling and portability, and versatility, make them especially interesting for adaptation to the increasingly challenging requirements of current clinical and point-of-care (POC) diagnostics. This has allowed the continuous development of strategies with improved performance in the clinical field that were unthinkable just a few years ago. After a brief introduction to the types and characteristics of clinically relevant biomarkers/samples, requirements for their analysis, and currently available methodologies, this review article provides a critical discussion of the most important developments and relevant applications involving electrochemical biosensors reported in the last five years in response to the demands of current diagnostic, prognostic, and therapeutic actions related to high prevalence and high mortality diseases and disorders. Special attention is paid to the rational design of surface chemistry and the use/modification of state-of-the-art nanomaterials to construct electrochemical bioscaffolds with antifouling properties that can be applied to the single or multiplex determination of biomarkers of accepted or emerging clinical relevance in particularly complex clinical samples, such as undiluted liquid biopsies, whole cells, and paraffin-embedded tissues, which have scarcely been explored using conventional techniques or electrochemical biosensing. Key points guiding future development, challenges to be addressed to further push the limits of electrochemical biosensors towards new challenging applications, and their introduction to the market are also discussed.

A DNA-linker-DNA bifunctional probe for simultaneous SERS detection of miRNAs via symmetric signal amplification

In this work, using a dual functional DNA-linker-DNA (DLD) probe, a new concept of a symmetric signal amplification (SSA) reaction is introduced to simultaneously analyze miRNAs. By coupling the surface-enhanced Raman scattering (SERS) technology with symmetric amplification modes, this flexible biosensing system exhibits high sensitivity and specificity.

Cytosolic delivery of siRNA by ultra-high affinity dsRNA binding proteins

Protein-based methods of siRNA delivery are capable of uniquely specific targeting, but are limited by technical challenges such as low potency or poor biophysical properties. Here, we engineered a series of ultra-high affinity siRNA binders based on the viral protein p19 and developed them into siRNA carriers targeted to the epidermal growth factor receptor (EGFR). Combined in trans with a previously described endosome-disrupting agent composed of the pore-forming protein Perfringolysin O (PFO), potent silencing was achieved in vitro with no detectable cytotoxicity. Despite concerns that excessively strong siRNA binding could prevent the discharge of siRNA from its carrier, higher affinity continually led to stronger silencing. We found that this improvement was due to both increased uptake of siRNA into the cell and improved pharmacodynamics inside the cell. Mathematical modeling predicted the existence of an affinity optimum that maximizes silencing, after which siRNA sequestration decreases potency. Our study characterizing the affinity dependence of silencing suggests that siRNA-carrier affinity can significantly affect the intracellular fate of siRNA and may serve as a handle for improving the efficiency of delivery. The two-agent delivery system presented here possesses notable biophysical properties and potency, and provide a platform for the cytosolic delivery of nucleic acids.

Multiplexed Electrochemical Detection of MiRNAs from Sera of Glioma Patients at Different Stages via the Novel Conjugates of Conducting Magnetic Microbeads and Diblock Oligonucleotide-Modified Gold Nanoparticles

MicroRNAs (miRNAs) serve as diagnostic and prognostic biomarkers for a wide variety of cancers. Via the novel conjugates of gold nanoparticle-coated magnetic microbeads (AuNP-MMBs) and the diblock oligonucleotide (ODN)-modified AuNPs, multiplexed electrochemical assay of miRNAs was performed. The hybridization to target miRNAs leads to the conformational change of the hairpin-structured ODN probes, and the attachment of the diblock ODN-modified AuNPs was achieved. By examining the oxidation peak currents of methylene blue (MB) and ferrocene (Fc) moieties residing on the diblock ODNs, simultaneous quantification of miRNA-182 and miRNA-381 was conducted. The detection signals were significantly enhanced due to the numerous MB and Fc tags on the AuNPs. The proposed assay was highly selective for discriminating miRNAs with similar sequences, and detection limits of 0.20 fM and 0.12 fM for miRNA-182 and miRNA-381, respectively, were achieved. The feasibility of the method for sensitive determination of miRNA-182 and miRNA-381 from serum samples of glioma patients at different stages was demonstrated. The sensing protocol thus holds great potential for early diagnosis and treatment of cancer patients.

Electrochemical Genosensing of Circulating Biomarkers

Management and prognosis of diseases requires the measurement in non- or minimally invasively collected samples of specific circulating biomarkers, consisting of any measurable or observable factors in patients that indicate normal or disease-related biological processes or responses to therapy. Therefore, on-site, fast and accurate determination of these low abundance circulating biomarkers in scarcely treated body fluids is of great interest for health monitoring and biological applications. In this field, electrochemical DNA sensors (or genosensors) have demonstrated to be interesting alternatives to more complex conventional strategies. Currently, electrochemical genosensors are considered very promising analytical tools for this purpose due to their fast response, low cost, high sensitivity, compatibility with microfabrication technology and simple operation mode which makes them compatible with point-of-care (POC) testing. In this review, the relevance and current challenges of the determination of circulating biomarkers related to relevant diseases (cancer, bacterial and viral infections and neurodegenerative diseases) are briefly discussed. An overview of the electrochemical nucleic acid-based strategies developed in the last five years for this purpose is given to show to both familiar and non-expert readers the great potential of these methodologies for circulating biomarker determination. After highlighting the main features of the reported electrochemical genosensing strategies through the critical discussion of selected examples, a conclusions section points out the still existing challenges and future directions in this field.

Electrochemical DNA sandwich biosensor based on enzyme amplified microRNA-21 detection and gold nanoparticles

In this work, a novel electrochemical biosensor for miRNA-21 determination, involving a sandwich hybridization assay onto gold nanoparticles modified pencil graphite electrode (PGE) and enzyme signal amplification was reported. The thiol terminated capture probe 1 (SH-P1) was immobilized on the electrode through AuS interaction. In the presence of target miRNA-21, SH-P1 hybridized with the first part of the target, however, the second part hybridizes with a biotinylated probe P2 (B-P2). Then, a streptavidin-conjugated alkaline phosphatase was immobilized by a specific binding of avidin-B-P2. The enzyme catalyzed the electro-inactive α-naphtyl phosphate to an electro-active α-naphtol. The miRNA-21 detection was achieved through the changes of α-naphtol oxidation signals observed at +0.12V vs Ag/AgCl with Differential Pulse Voltammetry. Under the optimal detection conditions, the biosensor exhibited selective and sensitive detection with a linear range from 200pM to 388nM and the detection limit was 100pM (10fmol in 100μL).

A novel electrochemical nanobiosensor for the ultrasensitive and specific detection of femtomolar-level gastric cancer biomarker miRNA-106a

Gastric cancer (GC) is the second leading cause of cancer-related deaths all over the world. miR-106a is a circulatory oncogenic microRNA (miRNA), which overexpresses in various malignancies, especially in GC. In this study, an ultrasensitive electrochemical nanobiosensor was developed for the detection of miR-106a using a double-specific probe methodology and a gold-magnetic nanocomposite as tracing tag. The successful modification of the electrode and hybridization with the target miRNA were confirmed by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) methods. Differential pulse voltammetry (DPV) was used for quantitative evaluation of miR-106a via recording the reduction peak current of gold nanoparticles. The electrochemical signal had a linear relationship with the concentration of the target miRNA ranging from 1 × 10^-3 pM to 1 × 10³ pM, and the detection limit was 3 × 10^-4 pM. The proposed miRNA-nanobiosensor showed remarkable selectivity, high specificity, agreeable storage stability, and great performance in real sample investigation with no pretreatment or amplification. Consequently, our biosensing strategy offers such a promising application to be used for clinical early detection of GC and additionally the screen of any miRNA sequence.

Magnetic Particles Coupled to Disposable Screen Printed Transducers for Electrochemical Biosensing

Ultrasensitive biosensing is currently a growing demand that has led to the development of numerous strategies for signal amplification. In this context, the unique properties of magnetic particles; both of nano- and micro-size dimensions; have proved to be promising materials to be coupled with disposable electrodes for the design of cost-effective electrochemical affinity biosensing platforms. This review addresses, through discussion of selected examples, the way that nano- and micro-magnetic particles (MNPs and MMPs; respectively) have contributed significantly to the development of electrochemical affinity biosensors, including immuno-, DNA, aptamer and other affinity modes. Different aspects such as type of magnetic particles, assay formats, detection techniques, sensitivity, applicability and other relevant characteristics are discussed. Research opportunities and future development trends in this field are also considered.

Biosensors for breast cancer diagnosis: A review of bioreceptors, biotransducers and signal amplification strategies

Breast cancer is highly prevalent in females and accounts for second highest number of deaths, worldwide. Cumbersome, expensive and time consuming detection techniques presently available for detection of breast cancer potentiates the need for development of novel, specific and ultrasensitive devices. Biosensors are the promising and selective detection devices which hold immense potential as point of care (POC) tools. Present review comprehensively scrutinizes various breast cancer biosensors developed so far and their technical evaluation with respect to efficiency and potency of selected bioreceptors and biotransducers. Use of glycoproteins, DNA biomarkers, micro-RNA, circulatory tumor cells (CTC) and some potential biomarkers are introduced briefly. The review also discusses various strategies used in signal amplification such as nanomaterials, redox mediators, p19 protein, duplex specific nucleases (DSN) and redox cycling.

Optimisation and Characterisation of Anti-Fouling Ternary SAM Layers for Impedance-Based Aptasensors

An aptasensor with enhanced anti-fouling properties has been developed. As a case study, the aptasensor was designed with specificity for human thrombin. The sensing platform was developed on screen printed electrodes and is composed of a self-assembled monolayer made from a ternary mixture of 15-base thiolated DNA aptamers specific for human thrombin co-immobilised with 1,6-hexanedithiol (HDT) and further passivated with 1-mercapto-6-hexanol (MCH). HDT binds to the surface by two of its thiol groups forming alkyl chain bridges and this architecture protects from non-specific attachment of molecules to the electrode surface. Using Electrochemical Impedance Spectroscopy (EIS), the aptasensor is able to detect human thrombin as variations in charge transfer resistance (R_ct) upon protein binding. After exposure to a high concentration of non-specific Bovine Serum Albumin (BSA) solution, no changes in the R_ct value were observed, highlighting the bio-fouling resistance of the surface generated. In this paper, we present the optimisation and characterisation of the aptasensor based on the ternary self-assembled monolayer (SAM) layer. We show that anti-fouling properties depend on the type of gold surface used for biosensor construction, which was also confirmed by contact angle measurements. We further studied the ratio between aptamers and HDT, which can determine the specificity and selectivity of the sensing layer. We also report the influence of buffer pH and temperature used for incubation of electrodes with proteins on detection and anti-fouling properties. Finally, the stability of the aptasensor was studied by storage of modified electrodes for up to 28 days in different buffers and atmospheric conditions. Aptasensors based on ternary SAM layers are highly promising for clinical applications for detection of a range of proteins in real biological samples.