Electrochemical DNA biosensor for human papillomavirus 16 detection in real samples

Designing a label-free electrochemical aptasensor based on polypyrrole-l-cysteine-reduced graphene oxide nanocomposite for detection of 25-hydroxyvitamin D3

Reliable and precise quantification of 25-hydroxyvitamin D3 in clinical samples is vital because vitamin D3 deficiency lead to several disorders, such as mental illness, osteoporosis, and coronavirus disease. Herein, we report the fabrication of a novel electrochemical aptasensor using a nanocomposite, including reduced graphene oxide, pyrrole, and l-cysteine, for the sensitive detection of 25-hydroxyvitamin D3 . Subsequently, the aptamer of 25-hydroxyvitamin D3 was immobilized on the surface of the modified electrode. Differential pulse voltammetry signals were utilized for studying the binding and measurement of 25-hydroxyvitamin D3 based on the oxidation peak. Under the optimum conditions, the designed electrochemical aptasensor exhibited a linear detection range of 0.001-150 nM, with a limit of detection of 0.006 nM. Furthermore, the proposed aptasensor selectively detected 25-hydroxyvitamin D3 compared to other analogs. Moreover, this aptasensor was successfully applied for the detection of 25-hydroxyvitamin D3 in human serum samples, which were quantified by the enzyme-linked immunosorbent assay method. The acceptable recoveries of 82.67%-111.07% demonstrated that this proposed electrochemical aptasensor can be a promising alternative for clinical methods of vitamin D determination.

Highly specific and sensitive sandwich-type electrochemiluminescence biosensor for HPV16 DNA detection based on the base-stacking effect and bovine serum albumin carrier platform

The detection of specific DNA sequences and the identification of single nucleotide polymorphisms are important for disease diagnosis. Herein, by combining the high specificity of the base-stacking effect with the high reproducibility of bovine serum albumin (BSA) modified electrodes and the high loading performance of DNA nanoclews (DNA NCs), a novel sandwich-type electrochemiluminescence (ECL) biosensor is reported for the highly specific detection of HPV16 (chosen as the model target). The capture probes are loaded by BSA carrier platforms modified on the gold electrode surface to improve reproducibility. DNA NCs loaded with a large amount of Ru(phen)32+ worked as signal probes. The template probe is composed of the complementary strand of the target and two free nucleic acid anchors at the head and tail. In the presence of the target DNA, the template probes can form stacked base pairs with target, generating high base-stacking energy. This results in the shorter free anchors of template probes being able to bind to the capture and signal probes. This eventually forms a sandwich structure that allows Ru(phen)32+ to be near the electrode surface, producing an ECL signal. There is a linear relationship between the signal and the target concentration range from 10 fM to 100 pM, with a detection limit of 5.03 fM (S/N=3). Moreover, the base-stacking effect has single base recognition ability for base pairs, effectively avoiding false positive signals. The results of this strategy for clinical samples are consistent with classical methods.

A graphitic nano-onion/molybdenum disulfide nanosheet composite as a platform for HPV-associated cancer-detecting DNA biosensors

An electrochemical DNA sensor that can detect human papillomavirus (HPV)-16 and HPV-18 for the early diagnosis of cervical cancer was developed by using a graphitic nano-onion/molybdenum disulfide (MoS₂) nanosheet composite. The electrode surface for probing DNA chemisorption was prepared via chemical conjugation between acyl bonds on the surfaces of functionalized nanoonions and the amine groups on functionalized MoS₂ nanosheets. The cyclic voltammetry profile of an 1:1 nanoonion/MoS₂ nanosheet composite electrode had an improved rectangular shape compared to that of an MoS₂ nanosheet elecrode, thereby indicating the amorphous nature of the nano-onions with sp₂ distancing curved carbon layers that provide enhanced electronic conductivity, compared to MoS₂ nanosheet only. The nanoonion/MoS₂ sensor for the DNA detection of HPV-16 and HPV-18, respectively, was measured at high sensitivity through differential pulse voltammetry (DPV) in the presence of methylene blue (MB) as a redox indicator. The DPV current peak was lowered after probe DNA chemisorption and target DNA hybridization because the hybridized DNA induced less effective MB electrostatic intercalation due to it being double-stranded, resulting in a lower oxidation peak. The nanoonion/MoS₂ nanosheet composite electrodes attained higher current peaks than the MoS₂ nanosheet electrode, thereby indicating a greater change in the differential peak probably because the nanoonions enhanced conductive electron transfer. Notably, both of the target DNAs produced from HPV-18 and HPV-16 Siha and Hela cancer cell lines were effectively detected with high specificity. The conductivity of MoS₂ improved by complexation with nano-onions provides a suitable platform for electrochemical biosensors for the early diagnosis of many ailments in humans.

Electrochemical bioplatform for the determination of the most common and carcinogenic human papillomavirus DNA

Nucleic acid-based analytical bioplatforms have gained importance as diagnostic tests for genomics and as early detection tools for diseases such as cancer. In this context, we report the development of an amperometric bioplatform for the determination of a specific human papillomavirus type 16 (HPV16) sequence. The bioplatform utilizes an immune-nucleic acid hybrid-sandwich assay. A biotinylated RNA capture probe (RNAbCp), complementary to the selected HPV16 target DNA sequence, was immobilised on the surface of streptavidin coated magnetic microbeads (Strep-MBs). The RNA/DNA heteroduplex resulting from the hybridization of the RNAbCP and the HPV16 target sequence was recognised by a commercial antibody that specifically bound to the heteroduplex (Ab_DNA-RNA). A horseradish-peroxide labeled secondary antibody (antiIgG-HRP) was used for the detection of Ab_DNA-RNA. Relying on amperometric detection of the resulting HRP-labeled magnetic bioconjugates captured on screen-printed electrodes (SPCEs) in the presence of H₂O₂ and hydroquinone (HQ), the biotool achieved a low limit of detection (0.5 pM) for the synthetic HPV16 target DNA. In addition, the developed bioplatform was able to discriminate between HPV16 positive and negative human cancer cells using only 25 ng of amplified DNA in a test time of 45 min.

Electrochemical DNA Biosensor Based on Immobilization of a Non-Modified ssDNA Using Phosphoramidate-Bonding Strategy and Pencil Graphite Electrode Modified with AuNPs/CB and Self-Assembled Cysteamine Monolayer

The present paper describes an alternative approach to the traditionally used covalent immobilization methods that require cost-intensive and complicated chemistry modification of a single-stranded DNA (ssDNA) capture probe. The low-cost pencil graphite electrode (PGE) modified with carbon black (CB) and gold nanoparticles (AuNPs) was used as an electrochemical platform and the non-modified ssDNA was immobilized on a self-assembled cysteamine modified AuNPs/CB-PGE through a phosphoramidate bond between the 5'-terminal phosphate group of ssDNA and the primary amine group of cysteamine. The microRNA-21 was used as a target model in the fabrication of this electrochemical DNA biosensor and the hybridization process with the complementary probe was monitored by differential pulse voltammetry using methylene blue (MB) as an electrochemical hybridization indicator. The decreased reduction peak current of MB shows a good linear correlation with the increased concentration of microRNA-21 target sequences because the MB signal is determined by the amount of exposed guanine bases. The linear range of the fabricated DNA biosensor was from 1.0 × 10^-8 to 5.0 × 10^-7 M with a detection limit of 1.0 × 10^-9 M. These results show that the covalent immobilization of a non-modified ssDNA capture probe through a phosphoramidate-bonding strategy could serve as a cost-effective and versatile approach for the fabrication of DNA biosensors related to a wide range of applications that cover the fields of medical diagnostic and environmental monitoring. The fabricated electrochemical DNA biosensor was used to analyze microRNA-21 in a (spiked) human serum sample and it showed satisfactory and encouraging results as an electrochemical DNA biosensor platform.

A Multianalyte Electrochemical Genosensor for the Detection of High-Risk HPV Genotypes in Oral and Cervical Cancers

Infection with high-risk human papillomavirus (HPV) is a major risk factor for oral and cervical cancers. Hence, we developed a multianalyte electrochemical DNA biosensor that could be used for both oral and cervical samples to detect the high-risk HPV genotypes 16 and 18. The assay involves the sandwich hybridization of the HPV target to the silica-redox dye reporter probe and capture probe, followed by electrochemical detection. The sensor was found to be highly specific and sensitive, with a detection limit of 22 fM for HPV-16 and 20 fM for HPV-18, between the range of 1 fM and 1 µM. Evaluation with oral and cervical samples showed that the biosensor result was consistent with the nested PCR/gel electrophoresis detection. The biosensor assay could be completed within 90 min. Due to its simplicity, rapidity, and high sensitivity, this biosensor could be used as an alternative method for HPV detection in clinical laboratories as well as for epidemiological studies.

The first diagnostic test for specific detection of Mycobacterium simiae using an electrochemical label-free DNA nanobiosensor

Mycobacterium simiae has been reported to be the most prevalent species of Nontuberculous mycobacteria (NTM) in many countries. As both phenotypic and molecular detection of M. simiae and other NTMs have limitations, finding an accurate, fast, and low-cost diagnostic method is critical for the management of infections. Here, we report the development of a new type of label-free electrochemical biosensor using a gold electrode decorated with l-cysteine/PAMAM dendrimer for specific targeting of M. simiae ITS sequence. DNA hybridization was monitored by measuring changes in the free guanine electrical signal with changing ssDNA target concentrations by differential pulse voltammetry (DPV) method. Response surface methodology (RSM) was applied for the optimization of variables affecting biosensor response. Under optimal conditions, the biosensor revealed a wide linear range from 10^-14 M to 10^-6 M and a detection limit of 1.40 fM. The fabricated biosensor showed an excellent selectivity to M. simiae in the presence of other similar pathogenic bacteria. Moreover, experimental results confirmed that this biosensor exhibited great precision and high reproducibility, hence provides a low-cost, label-free, and faster detection analysis, representing a novel strategy in detecting other NTMs.

Electrochemical bioassay coupled to LAMP reaction for determination of high-risk HPV infection in crude lysates

Electrochemical (EC) detection of DNA biomarkers represents an interesting tool in molecular oncology due to its sensitivity, simplicity, low cost or rapid times of measurement. However, majority of EC assays, same as most optical-based techniques, require preceding DNA extraction step to remove other cellular components, making these assays more laborious and time-consuming. One option to circumvent this is to use LAMP (loop-mediated amplification), an isothermal amplification technique that can amplify DNA directly in crude lysates in a short time at a constant temperature. Here, we coupled the LAMP reaction with EC readout to detect DNA from the two most common oncogenic human papillomavirus (HPV) types that cause cervical cancer in women, i.e. HPV 16 and HPV 18, directly in crude lysates without a need for DNA extraction step. We show that in crude lysates, the LAMP reaction was superior to PCR, with very good selectivity on a panel of cancer cell lines and with high sensitivity, enabling detection of HPV DNA from as few as 10 cells. As a proof of principle, we applied the assay to nineteen clinical samples both from uninfected women and from women suffering from cervical precancerous lesions caused by HPV 16 or HPV 18 genotypes. Clinical samples were simply boiled for 5 min in homogenization buffer without DNA extraction step, and amplified with LAMP. We obtained excellent concordance of our assay with PCR, reaching 100% sensitivity for both genotypes, 81.82% specificity for HPV 16 and 94.12% specificity for HPV 18. Proposed assay could be a straightforward, simple, rapid and sensitive alternative for early diagnostics of precancerous cervical lesions.

COVID-19 challenges: From SARS-CoV-2 infection to effective point-of-care diagnosis by electrochemical biosensing platforms

In January 2020, the World Health Organization (WHO) identified a new zoonotic virus, SARS-CoV-2, responsible for causing the COVID-19 (coronavirus disease 2019). Since then, there has been a collaborative trend between the scientific community and industry. Multidisciplinary research networks try to understand the whole SARS-CoV-2 pathophysiology and its relationship with the different grades of severity presented by COVID-19. The scientific community has gathered all the data in the quickly developed vaccines that offer a protective effect for all variants of the virus and promote new diagnostic alternatives able to have a high standard of efficiency, added to shorter response analysis time and portability. The industry enters in the context of accelerating the path taken by science until obtaining the final product. In this review, we show the principal diagnostic methods developed during the COVID-19 pandemic. However, when we observe the diagnostic tools section of an efficient infection outbreak containment report and the features required for such tools, we could observe a highlight of electrochemical biosensing platforms. Such devices present a high standard of analytical performance, are low-cost tools, easy to handle and interpret, and can be used in the most remote and low-resource regions. Therefore, probably, they are the ideal point-of-care diagnostic tools for pandemic scenarios.

Nitrogen-Doped Carbon Dots for Selective and Rapid Gene Detection of Human Papillomavirus Causing Cervical Cancer

According to WHO, cervical cancer is considered as one of the most frequently diagnosed cancers and the fourth main source of cancer death in women in 2020 worldwide. Hence, there is a need for development of cervical cancer screening with new rapid and cost-effective methods. Although there are few methods available for HPV identification, these techniques are less sensitive, time-consuming, and costly. An ultra-sensitive, selective, and label-free DNA-based impedimetric electrochemical genosensor is developed in this study to detect HPV-18 for cervical cancer. Electrochemical analysis was performed for the characterization of the sensing platform and for the detection of analyte. A single-stranded 25mer oligonucleotide DNA probe was immobilized onto a nitrogen-doped carbon nanodot-modified ITO electrode. Furthermore, the hybridization event was measured by testing the complementary single stranded DNA sequence in the samples. The sensor could distinguish between complementary as well as non-complementary sequences. Herein, impedance quantification demonstrated a limit of detection of 0.405 fM. The developed genosensor showed high selectivity toward HPV-18 in the clinical samples. This sensing platform can be considered as a rapid and selective method for the screening of HPV-18.

Comparison between various biosensor methods for human T-lymphotropic virus-1 (HTLV-1) detection

Due to the drawback of traditional and current diagnostic methods including serological and molecular assays, the development of the rapid and free-PCR techniques can be an alternative technique for the human T-cell lymphotropic virus (HTLV-1) DNA detection sequences. On the other hand, early detection of HTLV-1 prevents two dangerous diseases including Adult T-cell leukemia/lymphoma and HTLV-1 Associated Myelopathy/Tropical Spastic Paraparesis. The biosensor-based methods are sensitive techniques that can provide new opportunities to detect infectious diseases, particularly in the early stage. This study provides a comparative view among recently designed biosensors for the detection of HTLV-1.

Electronic and electrochemical viral detection for point-of-care use: A systematic review

Detecting viruses, which have significant impact on health and the economy, is essential for controlling and combating viral infections. In recent years there has been a focus towards simpler and faster detection methods, specifically through the use of electronic-based detection at the point-of-care. Point-of-care sensors play a particularly important role in the detection of viruses. Tests can be performed in the field or in resource limited regions in a simple manner and short time frame, allowing for rapid treatment. Electronic based detection allows for speed and quantitative detection not otherwise possible at the point-of-care. Such approaches are largely based upon voltammetry, electrochemical impedance spectroscopy, field effect transistors, and similar electrical techniques. Here, we systematically review electronic and electrochemical point-of-care sensors for the detection of human viral pathogens. Using the reported limits of detection and assay times we compare approaches both by detection method and by the target analyte of interest. Compared to recent scoping and narrative reviews, this systematic review which follows established best practice for evidence synthesis adds substantial new evidence on 1) performance and 2) limitations, needed for sensor uptake in the clinical arena. 104 relevant studies were identified by conducting a search of current literature using 7 databases, only including original research articles detecting human viruses and reporting a limit of detection. Detection units were converted to nanomolars where possible in order to compare performance across devices. This approach allows us to identify field effect transistors as having the fastest median response time, and as being the most sensitive, some achieving single-molecule detection. In general, we found that antigens are the quickest targets to detect. We also observe however, that reports are highly variable in their chosen metrics of interest. We suggest that this lack of systematisation across studies may be a major bottleneck in sensor development and translation. Where appropriate, we use the findings of the systematic review to give recommendations for best reporting practice.

Flexible sensor based on conducting polymer and gold nanoparticles for electrochemical screening of HPV families in cervical specimens

Considering the low sensitivity of cytological exams and high costs of the molecular methods, the development of diagnostic tests for effective diagnosis of HPV infections is a priority. In this work, biosensor composed of polypyrrole (PPy) films and gold nanoparticles (AuNPs) was obtained for specific detection of HPV genotypes. The biosensor was developed by using flexible electrodes based on polyethylene terephthalate (PET) strips coated with indium tin oxide (ITO). Polymeric films and AuNPs were obtained by electrosynthesis. Oligonucleotides sequences modified with functional amino groups were designed to recognize HPV gene families strictly. The modified oligonucleotides were chemically immobilized on the nanostructured platform. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for the analysis of the electrode modification and monitoring of molecular hybridization. Electrochemical changes were observed after exposure of the biosensors to plasmid samples and cervical specimens. The biosensor based on the BSH16 probe showed a linear concentration range for target HPV16 gene detection of 100 pg μL^-1 to 1 fg μL^-1. A limit of detection (LOD) of 0.89 pg μL^-1 and limit of quantification (LOQ) of 2.70 pg μL^-1 were obtained, with a regression coefficient of 0.98. Screening tests on cervical specimens were performed to evaluate the sensibility and specificity for HPV and its viral family. The expression of a biomarker for tumorigenesis (p53 gene) was also monitored. In this work, a flexible system has been successfully developed for label-free detection of HPV families and p53 gene monitoring with high specificity, selectivity, and sensitivity.

Electrochemical diagnostics of infectious viral diseases: Trends and challenges

Infectious diseases caused by viruses can elevate up to undesired pandemic conditions affecting the global population and normal life function. These in turn impact the established world economy, create jobless situations, physical, mental, emotional stress, and challenge the human survival. Therefore, timely detection, treatment, isolation and prevention of spreading the pandemic infectious diseases not beyond the originated town is critical to avoid global impairment of life (e.g., Corona virus disease - 2019, COVID-19). The objective of this review article is to emphasize the recent advancements in the electrochemical diagnostics of twelve life-threatening viruses namely - COVID-19, Middle east respiratory syndrome (MERS), Severe acute respiratory syndrome (SARS), Influenza, Hepatitis, Human immunodeficiency virus (HIV), Human papilloma virus (HPV), Zika virus, Herpes simplex virus, Chikungunya, Dengue, and Rotavirus. This review describes the design, principle, underlying rationale, receptor, and mechanistic aspects of sensor systems reported for such viruses. Electrochemical sensor systems which comprised either antibody or aptamers or direct/mediated electron transfer in the recognition matrix were explicitly segregated into separate sub-sections for critical comparison. This review emphasizes the current challenges involved in translating laboratory research to real-world device applications, future prospects and commercialization aspects of electrochemical diagnostic devices for virus detection. The background and overall progress provided in this review are expected to be insightful to the researchers in sensor field and facilitate the design and fabrication of electrochemical sensors for life-threatening viruses with broader applicability to any desired pathogens.

Rapid and label-free electrochemical DNA biosensor based on a facile one-step electrochemical synthesis of rGO-PPy-(L-Cys)-AuNPs nanocomposite for the HTLV-1 oligonucleotide detection

Human T cell leukemia virus type 1 (HTLV-1) as the first human retrovirus is currently a serious endemic health challenge. Despite the use of assorted molecular or serological assays for HTLV-1 detection, there are several limitations due to the lack of a confirmatory test that may affect the accuracy of the results. Herein, a novel label-free biosensor for the detection of HTLV-1 Tax gene has been reported. An electrochemical facile ecofriendly synthesis method has been demonstrated based on a synthesis of nanocomposite of reduced graphene oxide, polypyrrole, and gold nanoparticles (rGO-PPy-(l-Cys)-AuNPs) deposited on the surface of screen-printed carbon electrode. Electrochemical techniques were used to characterize and study the electrochemical behavior of the rGO-PPy-(l-Cys)-AuNPs, which exhibited a stable reference peak at 0.21 V associated with hybridization forms by applying the differential pulse voltammetry. The designed DNA biosensor presented a wide linear range from 0.1 fM to 100 µM and a low detection limit of 20 atto-molar. The proposed biosensor presented in this study provides outstanding selectivity, sensitivity, repeatability, and reproducibility.

Early-stage cervical cancer diagnosis based on an ultra-sensitive electrochemical DNA nanobiosensor for HPV-18 detection in real samples

BACKGROUND

In several years ago, infection with human papillomaviruses (HPVs), have been prevalent in the worlds especially HPV type 18, can lead to cervical cancer. Therefore, rapid, accurate, and early diagnosis of HPV for successful treatment is essential. The present study describes the development of a selective and sensitive electrochemical biosensor base on DNA, for early detection of HPV-18. For this purpose, a nanocomposite of reduced graphene oxide (rGO) and multiwalled carbon nanotubes (MWCNTs) were electrodeposited on a screen-printed carbon electrode (SPCE). Then, Au nanoparticles (AuNPs) were dropped on a modified SPCE. Subsequently, single strand DNA (ssDNA) probe was immobilized on the modified electrode. The link attached between AuNPs and probe ssDNA provided by L-cysteine via functionalizing AuNPs (Cys-AuNPs). The differential pulse voltammetry (DPV) assay was also used to electrochemical measurement. The measurement was based on the oxidation signals of anthraquninone-2-sulfonic acid monohydrate sodium salt (AQMS) before and after hybridization between the probe and target DNA.

RESULTS

The calibration curve showed a linear range between 0.01 fM to 0.01 nM with a limit of detection 0.05 fM. The results showed that the optimum concentration for DNA probe was 5 µM. The good performance of the proposed biosensor was achieved through hybridization of DNA probe-modified SPCE with extracted DNA from clinical samples.

CONCLUSIONS

According to the investigated results, this biosensor can be introduced as a proprietary, accurate, sensitive, and rapid diagnostic method of HPV 18 in the polymerase chain reaction (PCR) of real samples.

Review-Chemical and Biological Sensors for Viral Detection

Infectious diseases commonly occur in contaminated water, food, and bodily fluids and spread rapidly, resulting in death of humans and animals worldwide. Among infectious agents, viruses pose a serious threat to public health and global economy because they are often difficult to detect and their infections are hard to treat. Since it is crucial to develop rapid, accurate, cost-effective, and in-situ methods for early detection viruses, a variety of sensors have been reported so far. This review provides an overview of the recent developments in electrochemical sensors and biosensors for detecting viruses and use of these sensors on environmental, clinical and food monitoring. Electrochemical biosensors for determining viruses are divided into four main groups including nucleic acid-based, antibody-based, aptamer-based and antigen-based electrochemical biosensors. Finally, the drawbacks and advantages of each type of sensors are identified and discussed.

Early detection of cervical cancer based on high-risk HPV DNA-based genosensors: A systematic review

Human papillomavirus type (HPV) is a common cause of sexually transmitted disease (STD) in humans. HPV types 16 and 18 as the highest risk types are related with gynecologic malignancy and cervical cancer (CC) among women worldwide. Recently, considerable development of genosensors, which allows dynamic monitoring of hybridization events for HPV-16 and 18, has been a topic of focus by many researchers. In this systematic review, we highlight the route of development of DNA-based genosensory detection methods for diagnosis of high risk of HPV precancer. Biosensor detection methods of HPV-16 and 18 was investigated from 1994 to 2018 using several databases including PubMed, Cochrane Library, Scopus, Google Scholar, SID, and Scientific Information Database. Manual search of references of retrieved articles were also performed. A total of 50 studies were reviewed. By analyzing the most recent developed electrochemical biosensors for the identification of HPV, we observed that the sensor platform fabricated by Wang et al. holds the lowest detection limit reported in the literature for the DNA of HPV-16. Up to this date, optical, electrochemical, and piezoelectric systems are the main transducers used in the development of biosensors. Among the most sensitive techniques available to study the biorecognition activity of the sensors, we highlight the biosensors based fluorescent, EIS, and QCM. The current systematic review focuses on the sensory diagnostic methods that are being used to detect HPV-16 and 18 worldwide. Special emphasis is given on the sensory techniques that can diagnosis the individuals with CC. © 2018 BioFactors, 45(2):101-117, 2019.

Human Papillomavirus E6 biosensing: Current progression on early detection strategies for cervical Cancer

Prognosis of early cancer detection becomes one of the tremendous issues in the medical health system. Medical debates among specialist doctor and researcher in therapeutic approaches became a hot concern for cervix cancer deficiencies early screening, risk factors cross-reaction, portability device, rapid and free labeling system. The electrical biosensing based system showed credibility in higher specificity and selectivity due to hybridization of DNA duplex between analyte target and DNA probes. Electrical DNA sensor for cervix cancer has attracted too many attentions to researcher notification based on high performance, easy to handle, rapid system and possible to miniaturize. This review explores the current progression and future insignificant for HPV E6 genobiosensing for early Detection Strategies of Cervical Cancer.

Microfluidic-Based Genosensor To Detect Human Papillomavirus (HPV16) for Head and Neck Cancer

High-risk human papillomavirus (HPV) infection, mainly with HPV16 type, has been increasingly considered as an important etiologic factor in head and neck cancers. Detection of HPV16 is therefore crucial for these types of cancer, but clinical tests are not performed routinely in public health systems owing to the high cost and limitations of the existing tests. In this article, we report on a potentially low-cost genosensor capable of detecting low concentrations of HPV16 in buffer samples and distinguishing, with high accuracy, head and neck cancer cell lines according to their HPV16 status. The genosensor consisted of a microfluidic device that had an active layer of a HPV16 capture DNA probe (cpHPV16) deposited onto a layer-by-layer film of chitosan and chondroitin sulfate. Impedance spectroscopy was the principle of detection utilized, leading to a limit of detection of 10.5 pM for complementary ssDNA HPV16 oligos (ssHPV16). The genosensor was also able to distinguish among HPV16⁺ and HPV16^- cell lines, using the multidimensional projection technique interactive document mapping. Hybridization between the ssHPV16 oligos and cpHPV16 probe was confirmed with polarization-modulated infrared reflection-absorption spectroscopy, where PO₂ and amide I and amide II bands from adenine and thymine were monitored. The electrical response could be modeled as resulting from an adsorption process represented in a Freundlich model. Because the fabrication procedures of the microfluidic devices and genosensors and the data collection and analysis can be implemented at low cost, the results presented here amount to a demonstration of possible routine screening for HPV infections.

Advancements in electrochemical DNA sensor for detection of human papilloma virus - A review

Human papillomavirus (HPV) is one of the most common sexually transmitted disease, transmitted through intimate skin contact or mucosal membrane. The HPV virus consists of a double-stranded circular DNA and the role of HPV virus in cervical cancer has been studied extensively. Thus it is critical to develop rapid identification method for early detection of the virus. A portable biosensing device could give rapid and reliable results for the identification and quantitative determination of the virus. The fabrication of electrochemical biosensors is one of the current techniques utilized to achieve this aim. In such electrochemical biosensors, a single-strand DNA is immobilized onto an electrically conducting surface and the changes in electrical parameters due to the hybridization on the electrode surface are measured. This review covers the recent developments in electrochemical DNA biosensors for the detection of HPV virus. Due to the several advantages of electrochemical DNA biosensors, their applications have witnessed an increased interest and research focus nowadays.

Detection of Helicobacter pylori in dental plaque using a DNA biosensor for noninvasive diagnosis

H. pylori in dental plaque was detected with a DNA biosensor with results correlating well with the ¹³C urea breath test.

DNA sensors to assess the effect of VKORC1 and CYP2C9 gene polymorphisms on warfarin dose requirement in Chinese patients with atrial fibrillation

The optimal dose of warfarin depends on polymorphisms in the VKORC1 (the vitamin K epoxide reductase complex subunit (1) and CYP2C9 (cytochrome P450 2C9) genes. To minimize the risk of adverse reactions, warfarin dosages should be adjusted according to results from rapid and simple monitoring methods. However, there are few pharmacogenetic-guided warfarin dosing algorithms that are based on large cohorts from the Chinese population, especially patients with atrial fibrillation. This study aimed to validate a pharmacogenetic-guided warfarin dosing algorithm based on results from a new rapid electrochemical detection method used in a multicenter study. Three SNPs (CYP2C9 *2, *3 and VKORC1 c.-1639G > A) were genotyped by electrochemical detection using a sandwich-type format that included a 3' short thiol capture probe and a 5' ferrocene-labeled signal probe. A total of 1285 samples from four clinical hospitals were evaluated. Concordance rates between the results from the electrochemical DNA biosensor and the sequencing test were 99.8%. The results for gene distribution showed that most Chinese patients had higher warfarin susceptibility because mutant-type and heterozygotes were present in the majority of subjects (99.4%) at locus c.-1639G > A. When the International Warfarin Pharmacogenetics Consortium algorithm was used to estimate therapeutic dosages for 362 patients with AF and the values were compared with their actual dosages, the results revealed that 56.9% were similar to actual dosages (within the 20% range). A novel electrochemical detection method of CYP2C9 *2, *3and VKORC1 c.-1639G > A alleles was evaluated. The warfarin dosing algorithm based on data gathered from a large patient cohort can facilitate the reasonable and effective use of warfarin in Chinese patients with AF.

Diagnostics Strategies with Electrochemical Affinity Biosensors Using Carbon Nanomaterials as Electrode Modifiers

Early diagnosis is often the key to successful patient treatment and survival. The identification of various disease signaling biomarkers which reliably reflect normal and disease states in humans in biological fluids explain the burgeoning research field in developing new methodologies able to determine the target biomarkers in complex biological samples with the required sensitivity and selectivity and in a simple and rapid way. The unique advantages offered by electrochemical sensors together with the availability of high affinity and specific bioreceptors and their great capabilities in terms of sensitivity and stability imparted by nanostructuring the electrode surface with different carbon nanomaterials have led to the development of new electrochemical biosensing strategies that have flourished as interesting alternatives to conventional methodologies for clinical diagnostics. This paper briefly reviews the advantages of using carbon nanostructures and their hybrid nanocomposites as electrode modifiers to construct efficient electrochemical sensing platforms for diagnosis. The review provides an updated overview of some selected examples involving attractive amplification and biosensing approaches which have been applied to the determination of relevant genetic and protein diagnostics biomarkers.

Electrochemical paper-based peptide nucleic acid biosensor for detecting human papillomavirus

A novel paper-based electrochemical biosensor was developed using an anthraquinone-labeled pyrrolidinyl peptide nucleic acid (acpcPNA) probe (AQ-PNA) and graphene-polyaniline (G-PANI) modified electrode to detect human papillomavirus (HPV). An inkjet printing technique was employed to prepare the paper-based G-PANI-modified working electrode. The AQ-PNA probe baring a negatively charged amino acid at the N-terminus was immobilized onto the electrode surface through electrostatic attraction. Electrochemical impedance spectroscopy (EIS) was used to verify the AQ-PNA immobilization. The paper-based electrochemical DNA biosensor was used to detect a synthetic 14-base oligonucleotide target with a sequence corresponding to human papillomavirus (HPV) type 16 DNA by measuring the electrochemical signal response of the AQ label using square-wave voltammetry before and after hybridization. It was determined that the current signal significantly decreased after the addition of target DNA. This phenomenon is explained by the rigidity of PNA-DNA duplexes, which obstructs the accessibility of electron transfer from the AQ label to the electrode surface. Under optimal conditions, the detection limit of HPV type 16 DNA was found to be 2.3 nM with a linear range of 10-200 nM. The performance of this biosensor on real DNA samples was tested with the detection of PCR-amplified DNA samples from the SiHa cell line. The new method employs an inexpensive and disposable device, which easily incinerated after use and is promising for the screening and monitoring of the amount of HPV-DNA type 16 to identify the primary stages of cervical cancer.

Electrochemical chip-based genomagnetic assay for detection of high-risk human papillomavirus DNA

Cervical cancer, being the fourth leading cause of cancer death in women worldwide, predominantly originates from a persistent infection with a high-risk human papillomavirus (HPV). Detection of DNA sequences from these high-risk strains, mostly HPV-16 and HPV-18, represents promising strategy for early screening, which would help to identify women with higher risk of cervical cancer. In developing countries, inadequate screening options lead to disproportionately high mortality rates, making a fast and inexpensive detection schemes highly important. Electrochemical sensors and assays offer an alternative to current methods of detection. We developed an electrochemical-chip based assay, in which target HPV DNA is captured via magnetic bead-modified DNA probes, followed by an antidigoxigenin-peroxidase detection system at screen-printed carbon electrode chips, enabling parallel measurements of eight samples simultaneously. We show sensitive detection in attomoles of HPV DNA, selective discrimination between HPV-16 and HPV-18 and good reproducibility. Most importantly, we show application of the assay into both cancer cell lines and cervical smears from patients. The electrochemical results correlated well with standard methods, making this assay potentially applicable in clinical practice.

A Sensitive and Selective Label-Free Electrochemical DNA Biosensor for the Detection of Specific Dengue Virus Serotype 3 Sequences

Dengue fever is the most prevalent vector-borne disease in the world, with nearly 100 million people infected every year. Early diagnosis and identification of the pathogen are crucial steps for the treatment and for prevention of the disease, mainly in areas where the co-circulation of different serotypes is common, increasing the outcome of dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Due to the lack of fast and inexpensive methods available for the identification of dengue serotypes, herein we report the development of an electrochemical DNA biosensor for the detection of sequences of dengue virus serotype 3 (DENV-3). DENV-3 probe was designed using bioinformatics software and differential pulse voltammetry (DPV) was used for electrochemical analysis. The results showed that a 22-m sequence was the best DNA probe for the identification of DENV-3. The optimum concentration of the DNA probe immobilized onto the electrode surface is 500 nM and a low detection limit of the system (3.09 nM). Moreover, this system allows selective detection of DENV-3 sequences in buffer and human serum solutions. Therefore, the application of DNA biosensors for diagnostics at the molecular level may contribute to future advances in the implementation of specific, effective and rapid detection methods for the diagnosis dengue viruses.

An ultrasensitive electrochemical DNA biosensor based on graphene/Au nanorod/polythionine for human papillomavirus DNA detection

An ultrasensitive electrochemical DNA biosensor for human papillomavirus (HPV) detection was developed by electrochemical impedance spectroscopy and differential pulse voltammetry. A capture probe was immobilized on a glassy carbon electrode modified with graphene/Au nanorod/polythionine (G/Au NR/PT). Two auxiliary probes were designed and used to long-range self-assemble DNA nanostructure. The target DNA can connect DNA structure to the capture probe on the electrode surface. [Ru(phen)3](2+) was selected as a redox indicator for amplifying electrochemical signal significantly. Enhanced sensitivity was obtained through combining the excellent electric conductivity of G/Au NR/PT architecture and the long-range self-assembly DNA nanostructure with the multi-signal amplification. The DNA biosensor displayed excellent performance for HPV DNA detection over the range from 1.0×10(-13) to 1.0×10(-10) mol/L with a detection limit of 4.03×10(-14) mol/L. Furthermore, the proposed method can also be used for the detection of HPV DNA in human serum samples and provides a potential application of DNA detection in clinic research.