8-hydroxy-2'-deoxyguanosine (8-OHdG) biomarker detection down to picoMolar level on a plastic antibody film

Oxidative Stress Sensing System for 8-OHdG Detection Based on Plasma Coupled Electrochemistry by Transparent ITO/AuNTAs/PtNPs Electrode

8-Hydroxydeoxyguanosine (8-OHdG) is the most widely used oxidative stress biomarker of the free radical-induced oxidative damage product of DNA, which may allow a premature assessment of various diseases. This paper designs a label-free, portable biosensor device to directly detect 8-OHdG by plasma-coupled electrochemistry on a transparent and conductive indium tin oxide (ITO) electrode. We reported a flexible printed ITO electrode made from particle-free silver and carbon inks. After inkjet printing, the working electrode was sequentially assembled by gold nanotriangles (AuNTAs) and platinum nanoparticles (PtNPs). This nanomaterial-modified portable biosensor showed excellent electrochemical performance for 8-OHdG detection from 10 μg/mL to 100 μg/mL by our self-developed constant voltage source integrated circuit system. This work demonstrated a portable biosensor for simultaneously integrating nanostructure, electroconductivity, and biocompatibility to construct advanced biosensors for oxidative damage biomarkers. The proposed nanomaterial-modified ITO-based electrochemical portable device was a potential biosensor to approach 8-OHdG point-of-care testing (POCT) in various biological fluid samples, such as saliva and urine samples.

A Sensor-Based Perspective in Early-Stage Parkinson's Disease: Current State and the Need for Machine Learning Processes

Parkinson's disease (PD) is a progressive neurodegenerative disorder associated with dysfunction of dopaminergic neurons in the brain, lack of dopamine and the formation of abnormal Lewy body protein particles. PD is an idiopathic disease of the nervous system, characterized by motor and nonmotor manifestations without a discrete onset of symptoms until a substantial loss of neurons has already occurred, enabling early diagnosis very challenging. Sensor-based platforms have gained much attention in clinical practice screening various biological signals simultaneously and allowing researchers to quickly receive a huge number of biomarkers for diagnostic and prognostic purposes. The integration of machine learning into medical systems provides the potential for optimization of data collection, disease prediction through classification of symptoms and can strongly support data-driven clinical decisions. This work attempts to examine some of the facts and current situation of sensor-based approaches in PD diagnosis and discusses ensemble techniques using sensor-based data for developing machine learning models for personalized risk prediction. Additionally, a biosensing platform combined with clinical data processing and appropriate software is proposed in order to implement a complete diagnostic system for PD monitoring.

Aptamer-based colorimetric detection of the DNA damage marker 8-oxo-dG using cysteamine-stabilised gold nanoparticles

8-Oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG) is a crucial biomarker for oxidative DNA damage and carcinogenesis. Current strategies for 8-oxo-dG detection often require sophisticated instruments and qualified personnel. In this study, cysteamine-stabilised gold nanoparticles (cyst-AuNPs) were synthesised and used for colorimetric detection of 8-oxo-dG in urine. Sensing of 8-oxo-dG is based on the anti-aggregation of cyst-AuNPs, mediated by the specific recognition of 8-oxo-dG and its aptamer. In the absence of 8-oxo-dG, the aptamer was adsorbed onto the surface of cyst-AuNPs, resulting in aggregation and the development of a purple colour solution. Upon addition of the target molecule 8-oxo-dG, the aptamer specifically bound to it and could not induce the aggregation of cyst-AuNPs, leading to the dispersion of cyst-AuNPs in the solution. Simple visual examination could be used to monitor the purple-to-red colour change that started at 12 nM, a threshold concentration for visual analysis. The absorbance at 525 nm increased in direct relation to the number of the target molecule 8-oxo-dG. This aptamer/cyst-AuNPs system showed excellent sensing ability for the 8-oxo-dG concentration in the range of 15–100 nM, with a detection limit as low as 10.3 nM and a detection time of 30 min. Interference experiments showed that the developed colorimetric strategy had a good sensitivity. This simple and rapid colorimetric method has successfully been applied to inspect 8-oxo-dG concentration in real urine samples and provided recoveries between 93.6 and 94.1%, with a limit of quantification (LOQ) of 34.3 nM, which was comparable with an enzyme-linked immunosorbent-based detection of 8-oxo-dG. This new, easy-to-use, and rapid method could be used as an alternative and initiative strategy for the development of an on-site analysis of 8-oxo-dG in urine.

A colorimetric assay based on cysteamine-stabilized AuNPs and anti-8-oxo-dG aptamers for the detection of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG), which is a critical DNA damage marker, was developed.

Imprinted Fluorescent Cellulose Membranes for the On-Site Detection of Myoglobin in Biological Media

In this work, the conjugation of molecularly imprinted polymers (MIPs) to quantum dots (QDs) was successfully applied in the assembly of an imprinted cellulose membrane [hydroxy ethyl cellulose (HEC)/MIP@QDs] for the specific recognition of the cardiac biomarker myoglobin (Myo) as a sensitive, user-friendly, and portable system with the potential for point-of-care (POC) applications. The concept is to use the MIPs as biorecognition elements, previously prepared on the surface of semiconductor cadmium telluride QDs as detection particles. The fluorescent quenching of the membrane occurred with increasing concentrations of Myo, showing linearity in the interval range of 7.39-291.3 pg/mL in a1000-fold diluted human serum. The best membrane showed a linear response below the cutoff values for myocardial infarction (23 ng/mL), a limit of detection of 3.08 pg/mL, and an imprinting factor of 1.65. The incorporation of the biorecognition element MIPs on the cellulose substrate brings an approach toward a portable and user-friendly device in a sustainable manner. Overall, the imprinted membranes display good stability and selectivity toward Myo when compared with the nonimprinted membranes (HEC/NIP@QDs) and have the potential to be applied as a sensitive system for Myo detection in the presence of other proteins. Moreover, the conjugation of MIPs to QDs increases the sensitivity of the system for an optical label-free detection method, reaching concentration levels with clinical significance.

A new 8-oxo-7,8-2'deoxyguanosine nanoporous anodic alumina aptasensor for colorectal cancer diagnosis in blood and urine

Many important human diseases, and especially cancer, have been related to the overproduction of 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG). This molecule is a product of oxidative stress processes over nucleophilic bases in DNA. In this work, an aptasensor for the rapid, selective and accurate detection of this oncomarker is presented. The aptasensor consists of a nanoporous anodic alumina material loaded with a dye and is functionalized with an aptamer-based "molecular gate". In the presence of target 8-oxo-dG, the capping aptamer displaces from the surface due to the high affinity of the analyte with the capping aptamer, thus inducing delivery of the preloaded fluorescent dye. In contrast, in the absence of 8-oxo-dG, a poor payload delivery is accomplished. This aptamer-based nanodevice has great sensitivity for 8-oxo-dG, resulting in a LOD of 1 nM and a detection time of ca. 60 min. Moreover, the aptasensor is able to accurately detect 8-oxo-dG in unmodified urine and serum without pre-concentration treatments. This diagnostic tool is validated in a set of 38 urine and serum samples from patients diagnosed of colorectal cancer and control patients. These samples are also analyzed using a standardized and specific ELISA kit. The aptasensor displays excellent sensitivity (95.83/100%) and specificity (80/100%) for 8-oxo-dG detection in serum and urine samples, respectively. Our results may serve as a basis for the development of generalized fluorogenic diagnostic platforms for the easy diagnosis of cancer in biofluids as well as for monitoring therapeutic treatments and detection of relapses without the use of expensive equipment or trained personnel.

Biosensors in Parkinson's disease

Parkinson's disease (PD) is one of the most critical disorders of the elderly and strongly associated with increased disability, and reduced quality of life. PD is a progressive neurodegenerative disease affecting more than six million people worldwide. Evaluation of clinical manifestations, as well as movement disorders by a neurologist and some routine laboratory tests are the most important diagnostic methods for PD. However, routine and old methods have several disadvantages and limitations such as low sensitivity and selectivity, high cost, and need for advanced equipment. Biosensors technology opens up new diagnoses approach for PD with the use of a new platform that allows reliable, repeatable, and multidimensional identification to be made with minimal problem and discomfort for patients. For instance, biosensing systems can provide promising tools for PD treatment and monitoring. Amongst biosensor technology, electrochemical techniques have been at the frontline of this progress, thanks to the developments in material science, such as gold nanoparticles (AuNPs), quantum dots (QDs), and carbon nanotubes (CNTs). This paper evaluates the latest progress in electrochemical and optical biosensors for PD diagnosis.

Nanostructured material-based electrochemical sensing of oxidative DNA damage biomarkers 8-oxoguanine and 8-oxodeoxyguanosine: a comprehensive review

Oxidative DNA damage plays an important role in the pathogenesis of various diseases. Among oxidative DNA lesions, 8-oxoguanine (8-oxoG) and its corresponding nucleotide 8-oxo-2'-deoxyguanosine (8-oxodG), the guanine and deoxyguanosine oxidation products, have gained much attention, being considered biomarkers for oxidative DNA damage. Both 8-oxoG and 8-oxodG are used to predict overall body oxidative stress levels, to estimate the risk, to detect, and to make prognosis related to treatment of cancer, degenerative, and other age-related diseases. The need for rapid, easy, and low-cost detection and quantification of 8-oxoG and 8-oxodG biomarkers of oxidative DNA damage in complex samples, urine, blood, and tissue, caused an increasing interest on electrochemical sensors based on modified electrodes, due to their high sensitivity and selectivity, low-cost, and easy miniaturization and automation. This review aims to provide a comprehensive and exhaustive overview of the fundamental principles concerning the electrochemical determination of the biomarkers 8-oxoG and 8-oxodG using nanostructured materials (NsM), such as carbon nanotubes, carbon nanofibers, graphene-related materials, gold nanomaterials, metal nanoparticles, polymers, nanocomposites, dendrimers, antibodies and aptamers, and modified electrochemical sensors.

Genetic polymorphism of hOGG1 ser326cys and its association with breast cancer in Jammu and Kashmir

Background

8-Oxo-7, 8-dihydro-2'-deoxyguanosine (8-oxodG) is a potent DNA damage marker that leads to cellular oxidative stress. It is a DNA-repair enzyme that participates in "8-oxodG" DNA adducts removal. Previous studies show weak associations of rs1052133 (hOGG1) in breast cancer patients of Northern India. We performed this study to explore the variant rs1052133 (hOGG1) with breast in the population of Jammu and Kashmir (J and K).

Method

A polymerase chain reaction-restriction fragment length polymorphism -based single-nucleotide polymorphism (SNP) genotypic study was carried out in peripheral blood samples of 165 breast cancer patients and 200 healthy controls, using specific primers. Sanger sequencing verified the results.

Results

hOGG1-Ser326Cys polymorphism occurred frequently in cases as compared with controls. Data were evaluated by SPSS V.13 software, following Hardy-Weinberg equilibrium (P = 0.002 at OR 2.57; 95% CI [1.68-3.93]), which showed that the SNP rs1052133 had a significant association with increased risk of breast cancer.

Conclusion

Overall, the results of this analysis show that the hOGG1-Ser326Cys polymorphism may be associated with an increased risk for breast cancer in the J and K population.

Paper-Based Platform with an In Situ Molecularly Imprinted Polymer for β-Amyloid

Alzheimer's disease (AD) is one of the most common forms of dementia affecting millions of people worldwide. Currently, an easy and effective form of diagnosis is missing, which significantly hinders a possible improvement of the patient's quality of life. In this context, biosensors emerge as a future solution, opening the doors for preventive medicine and allowing the premature diagnosis of numerous pathologies. This work presents a pioneering biosensor that combines a bottom-up design approach using paper as a platform for the electrochemical recognition of peptide amyloid β-42 (Aβ-42), a biomarker for AD present in blood, associated with visible differences in the brain tissue and responsible for the formation of senile plaques. The sensor layer relies on a molecularly imprinted polymer as a biorecognition element, created on the carbon ink electrode's surface by electropolymerizing a mixture of the target analyte (Aβ-42) and a monomer (O-phenylenediamine) at neutral pH 7.2. Next, the template molecule was removed from the polymeric network by enzymatic and acidic treatments. The vacant sites so obtained preserved the shape of the imprinted protein and were able to rebind the target analyte. Morphological and chemical analyses were performed in order to control the surface modification of the materials. The analytical performance of the biosensor was evaluated by an electroanalytical technique, namely, square wave voltammetry. For this purpose, the analytical response of the biosensor was tested with standard solutions ranging from 0.1 ng/mL to 1 μg/mL of Aβ-42. The linear response of the biosensor went down to 0.1 ng/mL. Overall, the developed biosensor offered numerous benefits, such as simplicity, low cost, reproducibility, fast response, and repeatability less than 10%. All together, these features may have a strong impact in the early detection of AD.

Creation of glycoprotein imprinted self-assembled monolayers with dynamic boronate recognition sites and imprinted cavities for selective glycoprotein recognition

Glycoproteins are involved in the pathogenesis and development of many diseases and are used as biomarkers for disease diagnosis. It is highly desirable to develop highly sensitive and selective methods for the detection of glycoproteins without the use of antibodies. Imprinting of proteins represents one of the most challenging tasks. Glycoprotein imprinted self-assembled monolayers (SAMs) were created, for the first time, from an oligo(ethylene glycol) (OEG) terminated 1,2-dithiolane derivative linked through an alkyl chain incorporated with two amide groups (DHAP) and combined functional thiols of p-mercaptophenylboronic acid (PMBA) and p-aminothiophenol (PATP) in aqueous media, without the use of polymerization initiators. Combined action of PMBA and PATP was essential for the development of boronate recognition sites for glycoproteins at the physiological pH, attributed to the water molecule-mediated Lewis acid-base interactions between the electron-deficient PMBA and the electron-rich PATP. DHAP played key roles not only in cementation of imprinted cavities by means of double hydrogen bond networks through the amide groups but also in resistance to nonspecific protein binding by terminal OEG moieties, as well as hydrogen bond binding sites from the amide groups exposed to imprinted cavities. The created glycoprotein imprinted SAMs showed excellent recognition selectivity of target glycoproteins. The strategy for tailor-made glycoprotein imprinted SAMs explores a new avenue to the creation of intelligent biomaterials and fabrication of chemosensors.

A Review: New Trends in Electrode Systems for Sensitive Drug and Biomolecule Analysis

Drug and biomolecule analysis with high precision, fast response, not expensive, and user-friendly methods have been very important for developing technology and clinical applications. Electrochemical methods are highly capable for assaying the concentration of electroactive drug or biomolecule and supply excellent knowledge concerning its physical and chemical properties such as electron transfer rates, diffusion coefficients, electron transfer number, and oxidation potential. Electrochemical methods have been widely applied because of their accuracy, sensitivity, cheapness, and can applied on-site determinations of various substances. The progress on electronics has allowed developing reliable, more sensitive and less expensive instrumentations, which have significant contribution in the area of drug development, drug and biomolecule analysis. The developing new sensors for electrochemical analysis of these compounds have growing interest in recent years. Screen-printed based electrodes have a great interest in electrochemical analysis of various drugs and biomolecules due to their easy manufacturing procedure of the electrode allow the transfer of electrochemical laboratory experiments for disposable on-site analysis of some compounds. Paper based electrodes are also fabricated by new technology. They can be preferred due to their easy, cheap, portable, disposable, and offering high sensitivity properties for many application field such as environmental monitoring, food quality control, clinical diagnosis, drug, and biomolecules analysis. In this review, the recent electrochemical drug and biomolecule (DNA, RNA, µRNA, Biomarkers, etc.) studies will be presented that involve new trend disposable electrodes.

A carbon dot and gold nanoparticle-based fluorometric immunoassay for 8-hydroxy-2'-deoxyguanosine in oxidatively damaged DNA

A method is described for the fluorometric determination of DNA containing oxidatively damaged product 8-hydroxy-2'-deoxyguanosine (DNA-8-OHdG). Carbon dots (CDs) were modified with glutaraldehyde for DNA conjugation, and antibody against 8-OHdG was immobilized on gold nanoparticles (AuNPs). The presence of DNA-8-OHdG can be linked to CDs by reaction of amino groups on DNA with glutaraldehyde. AuNPs were brought closely to CDs by specific immune reaction between 8-OHdG and antibody on AuNPs. Under 350 nm photoexcitation, the emission of CDs with a peak at 440 nm is quenched by the AuNPs and not restored. In the presence of DNA-8-OHdG, the measured fluorescence intensity decreases and quenching efficiency increases. The limit of detection is 700 pM, and the assay works in the 0.01 nM to 25 μM DNA-8-OHdG concentration range. The method is perceived to possess a good potential as a tool for detecting biomarkers for DNA damage due to oxidative stress. Graphical abstract A fluorometric immunoassay for detecting 8-hydroxy-2'-deoxyguanosine (8-OHdG) in oxidatively damaged DNA is reported. It is based on the use of carbon dots (CDs) and gold nanoparticles (AuNPs). Black wavy lines represent DNA. Yellow polygonal sharps represent 8-OHdG. Blue and pink balls represent CDs and AuNPs, respectively.

Improving the fluorometric determination of the cancer biomarker 8-hydroxy-2'-deoxyguanosine by using a 3D DNA nanomachine

The authors describe a fluorometric method for improving the determination of the cancer biomarker 8-hydroxy-2'-deoxyguanosine (8-OHdG). A nicking endonuclease (NEase)-powered 3-D DNA nanomachine was constructed by assembling hundreds of carboxyfluorescein-labeled single strand oligonucleotides (acting as signal reporter) and tens of swing arms (acting as single-foot DNA walkers) on a gold nanoparticle (AuNP). The activity of this DNA nanomachine was controlled by introducing the protecting oligonucleotides. In the presence of aptamer against 8-OHdG, the protecting oligonucleotides are removed from the swing arms by toehold-mediated strand displacement reaction. In the next step, detached DNA walker hybridizes to the labelled DNA so that the DNA nanomachine becomes activated. Special sequences of signal reporter in the formed duplex can be recognized and cleaved by NEase. As a result, the DNA walker autonomously and progressively moves along the surface of the AuNP, thereby releasing hundreds of signal reporters and causing a rapid increase in green fluorescence. This 3-D nanomachine is highly efficient because one aptamer can release hundreds of signal reporters. These unique properties allowed for the construction of a DNA nanomachine-based method for sensitively detecting 8-OHdG in concentrations as low as 4 pM. This is three orders of magnitude lower compared to previously reported methods. Graphical abstract Schematic of a fluorometric method for determination of the cancer biomarker 8-hydroxy-2'-deoxyguanosine. A nicking endonuclease powered 3D-DNA nanomachine was used to improve the sensitivity. Limit of detection is three orders of magnitude lower than reported methods.

Determination of 8-hydroxy-2′-deoxyguanosine oxidative stress biomarker using dysprosium oxide nanoparticles@reduced graphene oxide

Electrochemical detection of 8-OHdG biomarker using Dy₂O₃@RGO/SPCE.

Paper-Based Sensing Device for Electrochemical Detection of Oxidative Stress Biomarker 8-Hydroxy-2'-deoxyguanosine (8-OHdG) in Point-of-Care

This work presents a cost-effective, label-free in point-of-care (POC) biosensor for the sensitive detection of 8-hydroxy-2′-deoxyguanosine (8-OHdG), the most abundant oxidative product of DNA, that may allow a premature assessment of cancer disease, thereby improving diagnosis, prognostics and survival rates. The device targets the direct detection of 8-OHdG by using for the first time a carbon-ink 3-electrode on a paper substrate coupled to Differential Pulse Voltammetry readings. This design was optimized by adding nanostructured carbon materials to the ink and the conducting polymer PEDOT, enhancing the electrocatalytic properties of the sensor towards 8-OHdG detection. Meanwhile, the ability of this oxidative stress biomarker to undertake an oxidation reaction enabled the development of the sensing electrochemical device without the need of chemical probes and long incubation periods. This paper-modified sensor presented high electrochemical performance on the oxidation of 8-OHdG with a wide linear range (50–1000 ng/ml) and a low detection limit (14.4 ng/ml). Thus, our results showed the development of a direct and facile sensor with good reproducibility, stability, sensitivity and more importantly, selectivity. The proposed carbon-based electrochemical sensor is a potential candidate to be miniaturized to small portable size, which make it applicable for in-situ 8-OHdG sensing in real biological samples.

MIP-Based Sensors: Promising New Tools for Cancer Biomarker Determination

Detecting cancer disease at an early stage is one of the most important issues for increasing the survival rate of patients. Cancer biomarker detection helps to provide a diagnosis before the disease becomes incurable in later stages. Biomarkers can also be used to evaluate the progression of therapies and surgery treatments. In recent years, molecularly imprinted polymer (MIP) based sensors have been intensely investigated as promising analytical devices in several fields, including clinical analysis, offering desired portability, fast response, specificity, and low cost. The aim of this review is to provide readers with an overview on recent important achievements in MIP-based sensors coupled to various transducers (e.g., electrochemical, optical, and piezoelectric) for the determination of cancer biomarkers by selected publications from 2012 to 2016.