Aptamers Targeting Cardiac Biomarkers as an Analytical Tool for the Diagnostics of Cardiovascular Diseases: A Review

Microbial and proteomic signatures of type 2 diabetes in an Arab population

BACKGROUND

The rising prevalence of Type 2 diabetes mellitus (T2D) in the Qatari population presents a significant public health challenge, highlighting the need for innovative approaches to early detection and management. While most efforts are centered on using blood samples for biomarker discovery, the use of saliva remains underexplored.

METHODS

Using noninvasive saliva samples from 2974 Qatari subjects, we analyzed the microbial communities from diabetic, pre-diabetic, and non-diabetic participants based on their HbA1C levels. The salivary microbiota was assessed in all subjects by sequencing the V1-V3 regions of 16S rRNA gene. For the proteomics profiling, we randomly selected 50 gender and age-matched non-diabetic and diabetic subjects and compared their proteome with SOMAscan. Microbiota and proteome profiles were then integrated to reveal candidate biomarkers for T2D.

RESULTS

Our results indicate that the salivary microbiota of pre-diabetic and diabetic individuals differs significantly from that of non-diabetic subjects. Specifically, a significant increase in the abundance of Campylobacter, Dorea, and Bacteroidales was observed in the diabetic subjects compared to their non-diabetic controls. Metabolic pathway prediction analysis for these bacteria revealed a significant overrepresentation of genes associated with fatty acid and lipid biosynthesis, as well as aromatic amino acid metabolism in the diabetic group. Additionally, we observed distinct differences in salivary proteomic profiles between diabetic and non-diabetic subjects. Notably, levels of Haptoglobin, Plexin-C1, and MCL-1 were elevated, while Osteopontin (SPP1), Histone1H3A (HIST3H2A), and Histone H1.2 were reduced in diabetic individuals. Furthermore, integrated correlation analysis of salivary proteome and microbiota data demonstrated a strong positive correlation between HIST1H3A and HIST3H2A with Porphyromonas sp., all of which were decreased in the diabetic group.

CONCLUSION

This is the first study to assess the salivary microbiota in T2D patients from a large cohort of the Qatari population. We found significant differences in the salivary microbiota of pre-diabetic and diabetic individuals compared to non-diabetic controls. Our study is also the first to assess the salivary proteome using SOMAScan in diabetic and non-diabetic subjects. Integration of the microbiota and proteome profiles revealed a unique signature for T2D that can be used as potential T2D biomarkers.

The significance of long chain non-coding RNA signature genes in the diagnosis and management of sepsis patients, and the development of a prediction model

Background

Sepsis is a life-threatening organ dysfunction condition produced by dysregulation of the host response to infection. It is now characterized by a high clinical morbidity and mortality rate, endangering patients' lives and health. The purpose of this study was to determine the value of Long chain non-coding RNA (LncRNA) RP3_508I15.21, RP11_295G20.2, and LDLRAD4_AS1 in the diagnosis of adult sepsis patients and to develop a Nomogram prediction model.

Methods

We screened adult sepsis microarray datasets GSE57065 and GSE95233 from the GEO database and performed differentially expressed genes (DEGs), weighted gene co-expression network analysis (WGCNA), and machine learning methods to find the genes by random forest (Random Forest), least absolute shrinkage and selection operator (LASSO), and support vector machine (SVM), respectively, with GSE95233 as the training set and GSE57065 as the validation set. Differentially expressed genes (DEGs), weighted gene co-expression network analysis (WGCNA), boxplot statistical analysis, and ROC analysis by Random Forest, Least Absolute Shrinkage and Selection Operator (LASSO), and Support Vector Machine (SVM) machine learning methods were used to identify characteristic genes and build the Nomogram Prediction model.

Results

GSE95233 yielded a total of 1069 genes, 102 of which were sepsis-related and 22 of which were non-sepsis controls. GSE57065 yielded a total of 899 genes, with 467 up-regulated and 432 down-regulated, including 82 sepsis-related genes and 25 non-sepsis control genes. WGCNA analysis excluded outlier samples, leaving 2,029 genes for relationship analysis between sepsis- and non-sepsis patient-associated LncRNA network representation modules, as well as Wein plots of differential genes versus genes in key modules of weighted co-expression network analysis to analyze gene intersections. Machine Learning found the sepsis-related characteristic LncRNAs RP3-508I15.21, RP11-295G20.2, LDLRAD4-AS1, and CTD-2542L18.1. The datasets GSE95233 and GSE57065 were analyzed using Boxplot against the screened genes listed above, respectively. The p-value between the sepsis and non-sepsis groups was less than 0.05, indicating that anomalies were statistically significant. CTD-2542L18.1 in dataset GSE57065 had an AUC value of 0.638, which was less than 0.7 and did not indicate diagnostic significance, but RP3-508I15.21, RP11-295G20.2, and LDLRAD4-AS1 had AUC values more than 0.7 after ROC analysis. All four sepsis-associated LncRNA ROC analyses in dataset GSE95233 exhibited AUC values more than 0.7, indicating diagnostic significance.

Conclusion

LncRNAs RP3_508I15.21, RP11_295G20.2, and LDLRAD4_AS1 have some utility in the diagnosis and treatment of adult sepsis patients, as well as some reference importance in guiding the diagnosis and treatment of clinical sepsis.

Novel DNA Aptamers to Dickkopf-1 Protein and Their Application in Colorimetric Sandwich Assays for Target Detection in Patients with Axial Spondyloarthritis

Chronic immunoinflammatory rheumatic diseases, such as axial spondyloarthritis (AxSpA), are accompanied by a dysregulation of bone remodeling. Among potential biomarkers of bone metabolism, the Wnt pathway antagonist, Dickkopf-1 (DKK-1), is of particular interest because of its potential to reflect a shift towards joint ossification or osteoporosis, but its diagnostic value needs validation. There is still a lack of stable and efficient methods of measuring serum DKK-1 levels suitable for longitude studies. The use of aptamer-based diagnostic assays could be very promising for this purpose. We generated novel anti-DKK-1 DNA aptamers from a combinatorial library with a pre-defined sequence pattern in the randomized region. This approach showed high efficacy, as only four SELEX rounds of selection produced high-affinity aptamers with dissociation constants ranging from 1.3 to 3.7 nM. A family of their truncated versions was also developed by rational design. Novel DNA aptamers functioned as capture components in a microplate ELISA-like assay with HRP-conjugated anti-DKK-1 antibody as a reporter component. We succeeded in revealing the aptamer/aptamer sandwich pairs that provided an aptamer-only sandwich colorimetric assay. The aptamer/antibody colorimetric test systems were also examined in the analyses of blood serum from AxSpA patients and shown sufficient workability. However, in a number of cases we registered significant differences between assays based on TD10 and DK4 aptamers and made some suggestions about the origin of this effect.

A Plasmonic Nanoledge Array Sensor for Selective Detection of Cardiovascular Disease Biomarkers in Human Whole Blood

Optical sensors face challenges when detecting ultralow amounts of analytes in whole blood, including signal quenching due to optical absorption and false positives due to nonspecific binding. This study introduces gold nanoscale array features termed nanoledges (NLs), which interact with incident white light to produce a transmitted surface plasmon resonance (tSPR) signal. This extraordinary optical transmission (EOT) spectrum occurs in the near-infrared (NIR) region, thereby minimizing signal quenching caused by visible-light absorption from blood proteins and pigments. To develop a sensitive, selective, and label-free optical biosensor for detecting various levels of cardiac troponin I (cTnI) in very small volumes of whole blood samples, DNA aptamers are tethered to the NL surface, specifically binding to the cTnI biomarker. This biological binding activity alters the refractive index at the NL surface, causing a peak shift in the EOT spectrum and enabling quantification of cTnI levels. The NL array chip demonstrated high sensitivity for cTnI detection in buffer, human serum (HS), and human whole blood (HB), with detection limits of 0.079, 0.084, and 0.097 ng/mL, respectively. Control measurements using blank target mediums and those containing up to 125 ng/mL of other proteins, such as myoglobin, creatine kinase, and heparin, showed minimal interference and high specificity. The NL plasmonic array's performance in biosensing underscores its promise for clinical analysis and its potential development as a point-of-care platform for early cardiovascular disease (CVD) diagnostics.

Advances in nanotechnological approaches for the detection of early markers associated with severe cardiac ailments

Mortality from cardiovascular disease (CVD) accounts for over 30% of all deaths globally, necessitating reliable diagnostic tools. Prompt identification and precise diagnosis are critical for effective personalized treatment. Nanotechnology offers promising applications in diagnostics, biosensing and drug delivery for prevalent cardiovascular diseases. Its integration into cardiovascular care enhances diagnostic accuracy, enabling early intervention and tailored treatment plans. By leveraging nanoscale innovations, healthcare professionals can address the complexities of CVD progression and customize interventions based on individual patient needs. Ongoing advancements in nanotechnology continue to shape the landscape of cardiovascular medicine, offering potential for improved patient outcomes and reduced mortality rates from these pervasive diseases.

Antidote-controlled DNA aptamer modulates human factor IXa activity

Thrombosis leads to elevated mortality rates and substantial medical expenses worldwide. Human factor IXa (HFIXa) protease is pivotal in tissue factor (TF)-mediated thrombin generation, and represents a promising target for anticoagulant therapy. We herein isolated novel DNA aptamers that specifically bind to HFIXa through systematic evolution of ligands by exponential enrichment (SELEX) method. We identified two distinct aptamers, seq 5 and seq 11, which demonstrated high binding affinity to HFIXa (Kd = 74.07 ± 2.53 nM, and 4.93 ± 0.15 nM, respectively). Computer software was used for conformational simulation and kinetic analysis of DNA aptamers and HFIXa binding. These aptamers dose-dependently prolonged activated partial thromboplastin time (aPTT) in plasma. We further rationally optimized the aptamers by truncation and site-directed mutation, and generated the truncated forms (Seq 5-1t, Seq 11-1t) and truncated-mutated forms (Seq 5-2tm, Seq 11-2tm). They also showed good anticoagulant effects. The rationally and structurally designed antidotes (seq 5-2b and seq 11-2b) were competitively bound to the DNA aptamers and effectively reversed the anticoagulant effect. This strategy provides DNA aptamer drug-antidote pair with effective anticoagulation and rapid reversal, developing advanced therapies by safe, regulatable aptamer drug-antidote pair.

The molecular interaction of six single-stranded DNA aptamers to cardiac troponin I revealed by docking and molecular dynamics simulation

Cardiac troponin I (cTnI) is a cardiac biomarker for diagnosing ischemic heart disease and acute myocardial infarction. Current biochemical assays use antibodies (Abs) due to their high specificity and sensitivity. However, there are some limitations, such as the high-cost production of Abs due to complex instruments, reagents, and steps; the variability of Abs quality from batch to batch; the low stability at high temperatures; and the difficulty of chemical modification. Aptamer overcomes the limitations of antibodies, such as relatively lower cost, high reproducibility, high stability, and ease of being chemically modified. Aptamers are three-dimensional architectures of single-stranded RNA or DNA that bind to targets such as proteins. Six aptamers (Tro1-Tro6) with higher binding affinity than an antibody have been identified, but the molecular interaction has not been studied. In this study, six DNA aptamers were modeled and docked to cTnI protein. Molecular docking revealed that the interaction between all aptamer and cTnI happened in the similar cTnI region. The interaction between aptamer and cTnI involved hydrophobic interaction, hydrogen bonds, π-cation interactions, π-stack interactions, and salt-bridge formation. The calculated binding energy of all complexes was negative, which means that the complex formation was thermodynamically favorable. The electrostatic energy term was the main driving force of the interaction between all aptamer and cTnI. This study could be used to predict the behavior of further modified aptamer to improve aptamer performance.

Comparative Study of Field-Effect Transistors Based on Graphene Oxide and CVD Graphene in Highly Sensitive NT-proBNP Aptasensors

Graphene-based materials are actively being investigated as sensing elements for the detection of different analytes. Both graphene grown by chemical vapor deposition (CVD) and graphene oxide (GO) produced by the modified Hummers' method are actively used in the development of biosensors. The production costs of CVD graphene- and GO-based sensors are similar; however, the question remains regarding the most efficient graphene-based material for the construction of point-of-care diagnostic devices. To this end, in this work, we compare CVD graphene aptasensors with the aptasensors based on reduced GO (rGO) for their capabilities in the detection of NT-proBNP, which serves as the gold standard biomarker for heart failure. Both types of aptasensors were developed using commercial gold interdigitated electrodes (IDEs) with either CVD graphene or GO formed on top as a channel of liquid-gated field-effect transistor (FET), yielding GFET and rGO-FET sensors, respectively. The functional properties of the two types of aptasensors were compared. Both demonstrate good dynamic range from 10 fg/mL to 100 pg/mL. The limit of detection for NT-proBNP in artificial saliva was 100 fg/mL and 1 pg/mL for rGO-FET- and GFET-based aptasensors, respectively. While CVD GFET demonstrates less variations in parameters, higher sensitivity was demonstrated by the rGO-FET due to its higher roughness and larger bandgap. The demonstrated low cost and scalability of technology for both types of graphene-based aptasensors may be applicable for the development of different graphene-based biosensors for rapid, stable, on-site, and highly sensitive detection of diverse biochemical markers.

A review on magnetic beads-based SELEX technologies: Applications from small to large target molecules

This review summarizes the stepwise strategy and key points for magnetic beads (MBs)-based aptamer selection which is suitable for isolating aptamers against small and large molecules via systematic evolution of ligands by exponential enrichment (SELEX). Particularities, if any, are discussed according to the target size. Examples targeting small molecules (<1000 Da) such as xenobiotics, toxins, pesticides, herbicides, illegal additives, hormones, and large targets such as proteins (biomarkers, pathogens) are discussed and presented in tabular formats. Of special interest are the latest advances in more efficient alternatives, which are based on novel instrumentation, materials or microelectronics, such as fluorescence MBs-SELEX or microfluidic chip system-assisted MBs-SELEX. Limitations and perspectives of MBs-SELEX are also reviewed. Taken together, this review aims to provide practical insights into MBs-SELEX technologies and their ability to screen multiple potential aptamers against targets from small to large molecules.

Diagnostic and Therapeutic Aptamers: A Promising Pathway to Improved Cardiovascular Disease Management

Despite advances in care, cardiovascular diseases remain the leading cause of death worldwide. As a result, identifying suitable biomarkers for early diagnosis and improving therapeutic and diagnostic strategies is crucial. Because of their significant advantages over other therapeutic approaches, nucleic-based therapies, particularly aptamers, are gaining increased attention. Aptamers are innovative synthetic polymers or oligomers of single-stranded DNA (ssDNA) or RNA molecules that can form 3-dimensional structures and thus interact with their targets with high specificity and affinity. Furthermore, they outperform classical protein-based antibodies in terms of in vitro selection, production, ease of modification and conjugation, high stability, low immunogenicity, and suitability for nanoparticle functionalization for targeted drug delivery. This work aims to review the advances made in the aptamers' field in biomarker detection, diagnosis, imaging, and targeted therapy, which highlight their huge potential in the management of cardiovascular diseases.

Femtosecond laser-induced fluorescence for rapid monitoring of cardiac troponin 1 as a cardiovascular disease biomarker

Medical diagnosis usually requires blood analysis of various biomarkers which are essential for disease detection and health status monitoring. Cardiac troponin 1 (cTn1) is a protein member of the cardiac troponin complex used for the diagnosis of several pathologies associated with cardiomyocyte necrosis. Laser-induced fluorescence (LIF) is a technique with high sensitivity and specificity, and it is one of the most significant developments used as an analytical tool for qualitative and quantitative analysis. The current study investigated the potential application of femtosecond LIF as a novel detection technique for rapid monitoring of cTn1 in clinical analysis. In the present study, the cTn1 (8 ng/ml) was excited over wavelengths ranging from 350 to 400 nm, and the LIF spectra were recorded. The results demonstrated that the maximum fluorescence intensity was observed at an excitation wavelength of 350 nm, with an emitted fluorescence peak centeredat 494 nm. At an excitation wavelength of 350 nm, different concentrations of cTn1 have been investigated and LIF spectra were obtained. The results revealed that the fluorescence peak intensity is concentration-dependent and increases linearly with increasing cTn1 concentration. These findings show that femtosecond LIF presents a unique, highly selective, precise, and direct approach to monitoring cTn1.

A DNA aptamer-based assay for the detection of soluble ST2, a prognostic biomarker for monitoring heart failure

Heart failure (HF) is emerging as a leading cause of death worldwide. Estimation of BNP levels is a routine diagnosis in these patients. However, in patients having high body-mass index (BMI), renal disease or in geriatric patients, BNP level is reported to be noisy and leads to incongruous conclusion. Thus, for better risk stratification among heart failure patients, it is imperative to look for a superior biomarker. In recent times, sST2 has shown promise as a biomarker. Identifying such biomarkers in peripheral blood of HF patients, need an affine and selective molecular recognition element. Thus, in the current study an aptamer (sS9_P) against sST2 was identified from an aptamer library. Systematic Evolution of Ligands through Exponential enrichment (SELEX) derived aptamer evinced role of its primer binding domains in maintaining its selectivity. This aptamer candidate demonstrated dissociation constant (Kd) in low nanomolar range, and the Limit of Detection (LOD) was ~4 ng. Circular dichroism confirms the formation of complex stem-loop like structure. The well characterized sS9_P aptamer was used in an Aptamer Linked Immobilized Sorbent Assay (ALISA) to detect sST2 level in patients' serum (n = 99). Aptamer sS9_P has shown significant discrimination to differentiate HF patients and healthy volunteers with a reasonable specificity (~83 %) with a modest sensitivity of ~64 %. While sST-2 antibody has shown poor specificity of ~44% but good sensitivity (~87%). The insight obtained from this study indicates that a combination of aptamer and antibody-based assay can be used to design a point-of-care assay for the rapid detection of HF patients in emergency settings.

Nucleic Acid Aptamer-Based Biosensors: A Review

Aptamers, short strands of either DNA, RNA, or peptides, known for their exceptional specificity and high binding affinity to target molecules, are providing significant advancements in the field of health. When seamlessly integrated into biosensor platforms, aptamers give rise to aptasensors, unlocking a new dimension in point-of-care diagnostics with rapid response times and remarkable versatility. As such, this review aims to present an overview of the distinct advantages conferred by aptamers over traditional antibodies as the molecular recognition element in biosensors. Additionally, it delves into the realm of specific aptamers made for the detection of biomarkers associated with infectious diseases, cancer, cardiovascular diseases, and metabolomic and neurological disorders. The review further elucidates the varying binding assays and transducer techniques that support the development of aptasensors. Ultimately, this review discusses the current state of point-of-care diagnostics facilitated by aptasensors and underscores the immense potential of these technologies in advancing the landscape of healthcare delivery.

New Insights into Cardiovascular Diseases Treatment Based on Molecular Targets

Cardiovascular diseases (CVDs) which consist of ischemic heart disease, stroke, heart failure, peripheral arterial disease, and several other cardiac and vascular conditions are one of the most common causes of death worldwide and often co-occur with diabetes mellitus and lipid disorders which worsens the prognosis and becomes a therapeutic challenge. Due to the increasing number of patients with CVDs, we need to search for new risk factors and pathophysiological changes to create new strategies for preventing, diagnosing, and treating not only CVDs but also comorbidities like diabetes mellitus and lipid disorders. As increasing amount of patients suffering from CVDs, there are many therapies which focus on new molecular targets like proprotein convertase subtilisin/kexin type 9 (PCSK9), angiopoietin-like protein 3, ATP-citrate lyase, or new technologies such as siRNA in treatment of dyslipidemia or sodium-glucose co-transporter-2 and glucagon-like peptide-1 in treatment of diabetes mellitus. Both SGLT-2 inhibitors and GLP-1 receptor agonists are used in the treatment of diabetes, however, they proved to have a beneficial effect in CVDs as well. Moreover, a significant amount of evidence has shown that exosomes seem to be associated with myocardial ischaemia and that exosome levels correlate with the severity of myocardial injury. In our work, we would like to focus on the above mechanisms. The knowledge of them allows for the appearance of new strategies of treatment among patients with CVDs.

Methods for detecting of cardiac troponin I biomarkers for myocardial infarction using biosensors: a narrative review of recent research

Background and Objective

In cardiovascular diseases (CVDs), acute myocardial infarction (AMI) is considered one of the leading causes of human death, and its diagnosis mainly relies on the detection of the cardiac biomarker troponin I. Traditional detection methods have certain limitations, which has prompted the development of methods with higher sensitivity and specificity. In recent years, biosensors, as an emerging technology, have been widely applied in the clinical medicine and biodetection fields. We retrieved and reviewed relevant articles published over the past 3 years and subsequently summarized the research progress of different types of biosensors in detecting cardiac troponin I and the challenges faced in achieving simple, specific, and portable point-of-care testing (POCT) technology for bedside rapid detection. The aim of this review is to serve as reference for the early diagnosis and treatment of CVDs.

Methods

This study searched for relevant literature published from 2019 to 2022 in the PubMed database of the National Center for Biotechnology Information (NCBI). The keywords used were as follows: "cardiac troponin I", "biosensor", "point-of-care testing", "electrochemical detection", and "surface-enhanced Raman spectroscopy".

Key Content and Findings

The review found that biosensor technology has high specificity and sensitivity in the detection of cardiac troponin I and is simpler and more convenient than is traditional laboratory testing. Its vigorous development can facilitate the diagnosis of AMI earlier and faster.

Conclusions

This study reviewed the progress of cardiac troponin I detection based on biosensing strategies. We found that cardiac troponin I detection methods based on biosensing strategies have their own advantages and disadvantages in clinical applications, and their sensitivity has been constantly improved. In the future, the detection of cardiac troponin I using biosensing technology will be simpler, faster, more sensitive, and portable.

Progress in the Optical Sensing of Cardiac Biomarkers

Biomarkers play key roles in the diagnosis, risk assessment, treatment and supervision of cardiovascular diseases (CVD). Optical biosensors and assays are valuable analytical tools answering the need for fast and reliable measurements of biomarker levels. This review presents a survey of recent literature with a focus on the past 5 years. The data indicate continuing trends towards multiplexed, simpler, cheaper, faster and innovative sensing while newer tendencies concern minimizing the sample volume or using alternative sampling matrices such as saliva for less invasive assays. Utilizing the enzyme-mimicking activity of nanomaterials gained ground in comparison to their more traditional roles as signaling probes, immobilization supports for biomolecules and for signal amplification. The growing use of aptamers as replacements for antibodies prompted emerging applications of DNA amplification and editing techniques. Optical biosensors and assays were tested with larger sets of clinical samples and compared with the current standard methods. The ambitious goals on the horizon for CVD testing include the discovery and determination of relevant biomarkers with the help of artificial intelligence, more stable specific recognition elements for biomarkers and fast, cheap readers and disposable tests to facilitate rapid testing at home. As the field is progressing at an impressive pace, the opportunities for biosensors in the optical sensing of CVD biomarkers remain significant.

Aptamer-Based Targeted Protein Degradation

The selective removal of misfolded, aggregated, or aberrantly overexpressed protein plays an essential role in maintaining protein-dominated biological processes. In parallel, the precise knockout of abnormal proteins is inseparable from the accurate identification of proteins within complex environments. Guided by these precepts, small molecules, or antibodies, are commonly used as protein recognition tools for developing targeted protein degradation (TPD) technology. Indeed, TPD has shown tremendous prospects in chronic diseases, rare diseases, cancer research, and other fields. Meanwhile, aptamers are short RNA or DNA oligonucleotides that can bind to target proteins with high specificity and strong affinity. Accordingly, aptamers are actively used in designing and constructing TPD technology. In this perspective, we provide a brief introduction to TPD technology in its current progress, and we summarize its application challenges. Recent advances in aptamer-based TPD technology are reviewed, together with corresponding challenges and outlooks.

Approaches and Challenges for Biosensors for Acute and Chronic Heart Failure

Heart failure (HF) is a cardiovascular disease defined by several symptoms that occur when the heart cannot supply the blood needed by the tissues. HF, which affects approximately 64 million people worldwide and whose incidence and prevalence are increasing, has an important place in terms of public health and healthcare costs. Therefore, developing and enhancing diagnostic and prognostic sensors is an urgent need. Using various biomarkers for this purpose is a significant breakthrough. It is possible to classify the biomarkers used in HF: associated with myocardial and vascular stretch (B-type natriuretic peptide (BNP), N-terminal proBNP and troponin), related to neurohormonal pathways (aldosterone and plasma renin activity), and associated with myocardial fibrosis and hypertrophy (soluble suppression of tumorigenicity 2 and galactin 3). There is an increasing demand for the design of fast, portable, and low-cost biosensing devices for the biomarkers related to HF. Biosensors play a significant role in early diagnosis as an alternative to time-consuming and expensive laboratory analysis. In this review, the most influential and novel biosensor applications for acute and chronic HF will be discussed in detail. These studies will be evaluated in terms of advantages, disadvantages, sensitivity, applicability, user-friendliness, etc.

Recent Advances in Impedimetric Biosensors Focusing on Myocardial Infarction Diagnosis

Acute myocardial infarction is the most common cardiovascular disease and 85% of cardiovascular disease-related deaths are associated with it. The variation in the cardiac troponin concentration is considered as the most significant judge index for acute myocardial infarction diagnosis. Here, a comprehensive insights is given about the impedimetric methods as powerful electrochemical biosensing platforms for cardiac troponin evaluation. Focusing on nano materials, various impedimetric techniques including faradaic and non-faradaic techniques and different transducer modification techniques are addressed. The steps taken by each of the studied platforms to solve the existing problems are discussed and their advantages and drawbacks are highlighted. A glance at the provided table is given a mind into the features of each impedimetric sensors and their comparison are provided.

One-Step Photochemical Immobilization of Aptamer on Graphene for Label-Free Detection of NT-proBNP

A novel photochemical technological route for one-step functionalization of a graphene surface with an azide-modified DNA aptamer for biomarkers is developed. The methodology is demonstrated for the functionalization of a DNA aptamer for an N-terminal B-type natriuretic peptide (NT-proBNP) heart failure biomarker on the surface of a graphene channel within a system based on a liquid-gated graphene field effect transistor (GFET). The limit of detection (LOD) of the aptamer-functionalized sensor is 0.01 pg/mL with short response time (75 s) for clinically relevant concentrations of the cardiac biomarker, which could be of relevance for point-of-care (POC) applications. The novel methodology could be applicable for the development of different graphene-based biosensors for fast, stable, real-time, and highly sensitive detection of disease markers.