Electrochemical impedance spectroscopy characterization of mercaptopropionic acid capped ZnS nanocrystal based bioelectrode for the detection of the cardiac biomarker—myoglobin

Advancements in electrochemical immunosensors towards point-of-care detection of cardiac biomarkers

Cardiovascular disease remains the leading cause of death worldwide, with mortality rates increasing annually. This underscores the urgent need for accurate diagnostic and monitoring tools. Electrochemical detection has emerged as a promising method for swiftly and precisely measuring specific biomarkers in bodily fluids. This approach is not only cost-effective and efficient compared to traditional clinical methods, but it can also be tailored to detect individual biomarkers, which makes it particularly well-suited for point-of-care (POC) applications. The ability to conduct testing at the point of care is crucial for timely interventions and personalized disease management, empowering healthcare providers to tailor treatment plans based on real-time biomarker data. Thanks to recent advancements in nanomaterials, we've seen significant progress in electrochemical detection, leading to the development of specialized rapid immunoassay systems. These systems utilize specific antibodies to target molecules, expanding the range of detectable biomarkers. This innovation has the potential to revolutionize the diagnosis and treatment of cardiovascular diseases by enhancing detection sensitivity and specificity. Ultimately, these advancements aim to improve patient outcomes by enabling earlier diagnosis, more precise monitoring, and personalized therapeutic interventions, which will contribute to more effective management of cardiovascular health globally.

Preparation and Spectrochemical characterization of Ni-doped ZnS nanocomposite for effective removal of emerging contaminants and hydrogen Production: Reaction Kinetics, mechanistic insights

In this study, we report the successful synthesis of Ni-doped ZnS nanocomposite via a green route using ethanolic crude extract of Avena fatua. The as-synthesized nanocomposite was comprehensively characterized using Dynamic light scattering (DLS), Zeta potential, scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and Atomic force microscopy (AFM). These analyses provided detailed insights into the size, morphology, composition, surface properties, and structural characteristics of the nanocomposite. Subsequently, the synthesized nanocomposite was evaluated for their photocatalytic performance against the organic dye Methyl orange. Remarkably, the nanocomposite exhibited rapid and efficient degradation of Methyl orange, achieving 90 % degradation within only 30 min of irradiation under UV light. Moreover, the photocatalyst demonstrated an exceptional hydrogen production rate, reaching 167.73 µmolg-1h-1, which is approximately 4.5 times higher than that of its pristine counterparts. These findings highlight the significant potential of Ni-doped ZnS nanocomposite as highly efficient photocatalysts for wastewater treatment and hydrogen production applications.

Biosensing Platforms for Cardiac Biomarker Detection

Myocardial infarction (MI) is a cardiovascular disease that occurs when there is an elevated demand for myocardial oxygen as a result of the rupture or erosion of atherosclerotic plaques. Globally, the mortality rates associated with MI are steadily on the rise. Traditional diagnostic biomarkers employed in clinical settings for MI diagnosis have various drawbacks, prompting researchers to investigate fast, precise, and highly sensitive biosensor platforms and technologies. Biosensors are analytical devices that combine biological elements with physicochemical transducers to detect and quantify specific compounds or analytes. These devices play a crucial role in various fields including healthcare, environmental monitoring, food safety, and biotechnology. Biosensors developed for the detection of cardiac biomarkers are typically electrochemical, mass, and optical biosensors. Nanomaterials have emerged as revolutionary components in the field of biosensing, offering unique properties that significantly enhance the sensitivity and specificity of the detection systems. This review provides a comprehensive overview of the advancements and applications of nanomaterial-based biosensing systems. Beginning with an exploration of the fundamental principles governing nanomaterials, we delve into their diverse properties, including but not limited to electrical, optical, magnetic, and thermal characteristics. The integration of these nanomaterials as transducers in biosensors has paved the way for unprecedented developments in analytical techniques. Moreover, the principles and types of biosensors and their applications in cardiovascular disease diagnosis are explained in detail. The current biosensors for cardiac biomarker detection are also discussed, with an elaboration of the pros and cons of existing platforms and concluding with future perspectives.

Development of sensitive and stable electrochemical impedimetric biosensor based on T1R1 receptor and its application to detection of umami substances

Umami substances can provide a palatable flavour for food. In this study, an electrochemical impedimetric biosensor was developed for detecting umami substances. This biosensor was fabricated by immobilising T1R1 onto AuNPs/reduced graphene oxide/chitosan which was in advance electro-deposited onto a glassy carbon electrode. The evaluation by the electrochemical impedance spectrum method showed that the T1R1 biosensor performed well with low detection limits and wide linear ranges. Under the optimised incubation time (60 s), the electrochemical response was linearly related to the concentrations of the detected targets monosodium glutamate and inosine-5'-monophosphate within their respective linear range of 10^-14 to 10^-9 M and 10^-16 to 10^-13 M. The low detection limit of monosodium glutamate and inosine-5'-monophosphate was 10^-15 M and 10^-16 M, respectively. Moreover, the T1R1 biosensor exhibited high specificity to umami substances even in the real food sample. The developed biosensor still retained 89.24% signal intensity after 6-day storage, exhibiting a desirable storability.

An electrochemical impedance aptasensor based on selenomolybdate nanodot/antimonene hybrid for platelet-derived growth factor-BB

The aim of the present study was to design a unique bioelectrode for the quantitative analysis of a potential cancer biomarker, platelet-derived growth factor-BB (PDGF-BB), which can be used for the early detection of cancer. We report the fabrication of succinic acid-capped selenomolybdate polyoxometalate nanodots, POM (SA), decorated antimonene hybrid film on glassy carbon as a suitable bioelectrode. Antimonene nanosheets, synthesized by the chemical exfoliation of antimony provided a large surface area for the symmetric dispersal of POM (SA) nanodots, resulting in site-specific covalent immobilization of the aptamer, PDGF-BB. A comprehensive electrochemical immunosensing investigation was performed on the electrode for sensing of a target antigen, Ag-PDGF-BB. The sensitivity, selectivity, and reproducibility of the bioelectrode were investigated using a best-fit equivalent circuit model that fitted the impedance response. The bioelectrode showed a linear impedimetric response in a broad range for Ag-PDGF-BB (10 pM to 100 nM in pH 7.4 PB) with a limit of detection of 3.5 pM and sensitivity of 80 Ω cm² per decade. The response sensitivity of the POM(SA)/antimonene hybrid based bioelectrode toward PDGF-BB was approximately ∼1.8-fold higher than that of the POM(SA) only modified bioelectrode. The dissociation constant of immunoreaction between the aptamer-functionalized bioelectrode and target Ag-PDGF-BB was 76 nM, indicating a high binding affinity between the aptamer PDGF-BB and target Ag-PDGF-BB on the electrode surface.

Label-Free Myoglobin Biosensor Based on Pure and Copper-Doped Titanium Dioxide Nanomaterials

In this study, using pure and copper-doped titanium dioxide (Cu-TiO₂) nanostructures as the base matrix, enzyme-less label free myoglobin detection to identify acute myocardial infarction was performed and presented. The Cu-TiO₂ nanomaterials were prepared using facile sol-gel method. In order to comprehend the morphologies, compositions, structural, optical, and electrochemical characteristics, the pure and Cu-TiO₂ nanomaterials were investigated by several techniques which clearly revealed good crystallinity and high purity. To fabricate the enzyme-less label free biosensor, thick films of synthesized nanomaterials were applied to the surface of a pre-fabricated gold screen-printed electrode (Au-SPE), which serves as a working electrode to construct the myoglobin (Mb) biosensors. The interference study of the fabricated biosensor was also carried out with human serum albumin (HSA) and cytochrome c (cyt-c). Interestingly, the Cu-doped TiO₂ nanomaterial-based Mb biosensor displayed a higher sensitivity of 61.51 µAcm^-2/nM and a lower detection limit of 14 pM with a response time of less than 10 ms.

Electrochemical microgap immunosensors for selective detection of pathogenic Aspergillus niger

Aspergillus niger (A. niger) is a well-known allergenic, harmful fungus in the indoor environment that can cause asthmatic symptoms and atopy. Previous immunosensing approach suffers from an insufficient detection limit, mainly because there are no techniques for target amplification. We report an electrochemical immunosensor that selectively quantifies the A. niger based on the detection of extracellular proteins by using a specific interaction with antibody. The sensor was designed to show a decrease in redox current upon binding of the antigens secreted from A. niger onto an antibody-immobilized surface between the interdigitated electrodes. The extracellular proteins were profiled by LC-MS/MS to identify the antigens existing in the A. niger solution. Since the targets of the sensor are the proteins, its sensitivity and selectivity remain almost intact even after filtration of the spores. It was also found that the use of secretion promoter in the sampling stage greatly improved the sensor's limit of detection (LOD) for the spores. By this, the LOD was lowered by a few orders of magnitude so as to reach the value as low as ~10¹ spores/mL.

Quantitative Evaluation of Burn Injuries Based on Electrical Impedance Spectroscopy of Blood with a Seven-Parameter Equivalent Circuit

A quantitative and rapid burn injury detection method has been proposed based on the electrical impedance spectroscopy (EIS) of blood with a seven-parameter equivalent circuit. The degree of burn injury is estimated from the electrical impedance characteristics of blood with different volume proportions of red blood cells (RBCs) and heated red blood cells (HRBCs). A quantitative relationship between the volume portion H_HCT of HRBCs and the electrical impedance characteristics of blood has been demonstrated. A seven -parameter equivalent circuit is employed to quantify the relationship from the perspective of electricity. Additionally, the traditional Hanai equation has been modified to verify the experimental results. Results show that the imaginary part of impedance Z_Imt under the characteristic frequency (f_c) has a linear relationship with H_HCT which could be described by Z_Imt = −2.56H_HCT − 2.01 with a correlation coefficient of 0.96. Moreover, the relationship between the plasma resistance R_p and H_HCT is obtained as R_p = −7.2H_HCT + 3.91 with a correlation coefficient of 0.96 from the seven -parameter equivalent circuit. This study shows the feasibility of EIS in the quantitative detection of burn injury by the quantitative parameters Z_Imt and R_p, which might be meaningful for the follow-up clinical treatment for burn injury.

Nanodiamonds and hydrogen-substituted graphdiyne heteronanostructure for the sensitive impedimetric aptasensing of myocardial infarction and cardiac troponin I

A novel heteronanostructure of nanodiamonds (NDs) and hydrogen-substituted graphdiyne (HsGDY) (denoted as HsGDY@NDs) was prepared for the impedimetric aptasensing of biomarkers such as myoglobin (Myo) and cardiac troponin I (cTnI). Basic characterizations revealed that the HsGDY@NDs were composed of nanospheres with sizes of 200-500 nm. In these nanospheres, NDs were embedded within the HsGDY network. The HsGDY@NDs nanostructure, which integrated the good chemical stability and three-dimensional porous networks of HsGDY, and the good biocompatibility and electrochemical activity of NDs, could immobilize diverse aptamer strands and recognize target biomarkers. Compared with HsGDY- and NDs-based aptasensors, the HsGDY@NDs-based aptasensors exhibited superior sensing performances for Myo and cTnI, giving low detection limits of 6.29 and 9.04 fg mL^-1 for cTnI and Myo, respectively. In addition, the HsGDY@NDs-based aptasensors exhibited high selectivity, good stability, reproducibility, and acceptable applicability in real human serum. Thus, the construction of HsGDY@NDs-based aptasensor is expected to broaden the application of porous organic frameworks in the sensing field and provide a prospective approach for the early detection of disease biomarkers.

Cholesterol oxidase immobilized inulin based nanocomposite as the sensing material for cholesterol in biological and food samples

In the present study, inulin based nanocomposite viz., TiO₂-MWCNT@Inulin was prepared by embedding Inulin (a biopolymer extracted from Allium sativum L.) with TiO₂ and MWCNTs. The morphology of the prepared nanocomposite was characterized by High Resolution transmission electron microscopy (HRTEM). Cholesterol oxidase (ChOx) enzyme was then immobilized into the nanocomposite and the immobilization was examined by UV-vis and FT-IR spectral studies. The ChOx immobilized nanocomposite was integrated into carbon paste (CP) matrix to prepare the working electrode for the sensing of cholesterol. Electrochemical characterization of the modified CP/TiO₂-MWCNT@Inulin/ChOx electrode was done by cyclic voltammetric (CV) and electrochemical impedance spectroscopic (EIS) studies. Differential pulse voltammetric (DPV) studies were carried out to determine the concentration of cholesterol at the interface of the newly fabricated electrode. The fabricated electrode demonstrated a linear range from 83 μM to 14.28 mM, low limit of detection (35 μM), good sensitivity (21.26 μA mM^-1  cm^-2), low K_m (0.49 mM), high stability (120 days) and good selectivity. The presence of Inulin biopolymer played a vital role in attaching ChOx enzyme firmly to the nanocomposite thereby enhancing the stability and electron transfer efficiency of the electrode. The analysis of product that was formed within the electrochemical cell during the electrochemical oxidation of cholesterol was performed by using sodium nitroprusside. This resulted in a deep purple coloured solution which suggested the electrochemical conversion of cholesterol to cholestenone. The practical applicability of the fabricated electrode was also assessed by the determination of cholesterol in spiked blood serum and milk samples.

Nanomolar level sensing of glucose in food samples using glucose oxidase confined MWCNT-Inulin-TiO2 bio-nanocomposite

Development of an effective sensor for sensing glucose in commercially available "sugar free" food products is important as people are becoming diabetic health conscious. Although multi-walled carbon nanotubes (MWCNTs) possess interesting electrical properties, their hydrophobic nature limits their applications. Their hydrophilicity can be improved through modification. In the present study, Inulin, that was isolated from Allium sativum L. using hot water diffusion and incorporated with titanium dioxide (TiO₂), was used for the modification of MWCNTs. The as-synthesized MWCNT-Inulin-TiO₂ bio-nanocomposite immobilized with glucose oxidase (GOx) was incorporated into the carbon paste matrix and was utilized for the sensing of glucose in food products. Differential pulse voltammetric studies revealed that the fabricated electrode demonstrated good linear range (1.6 nM to 1 μM) and was sensitive to nanomolar concentrations of glucose with a very low limit of detection up to 0.82 nM and exhibited a long term stability of 150 days.

Nanoscale Technologies for Prevention and Treatment of Heart Failure: Challenges and Opportunities

The adult myocardium has a limited regenerative capacity following heart injury, and the lost cells are primarily replaced by fibrotic scar tissue. Suboptimal efficiency of current clinical therapies to resurrect the infarcted heart results in injured heart enlargement and remodeling to maintain its physiological functions. These remodeling processes ultimately leads to ischemic cardiomyopathy and heart failure (HF). Recent therapeutic approaches (e.g., regenerative and nanomedicine) have shown promise to prevent HF postmyocardial infarction in animal models. However, these preclinical, clinical, and technological advancements have yet to yield substantial enhancements in the survival rate and quality of life of patients with severe ischemic injuries. This could be attributed largely to the considerable gap in knowledge between clinicians and nanobioengineers. Development of highly effective cardiac regenerative therapies requires connecting and coordinating multiple fields, including cardiology, cellular and molecular biology, biochemistry and chemistry, and mechanical and materials sciences, among others. This review is particularly intended to bridge the knowledge gap between cardiologists and regenerative nanomedicine experts. Establishing this multidisciplinary knowledge base may help pave the way for developing novel, safer, and more effective approaches that will enable the medical community to reduce morbidity and mortality in HF patients.

Enzyme-less sensing of the kidney dysfunction biomarker creatinine using an inulin based bio-nanocomposite

Enzyme-less electrochemical sensing of creatinine using an inulin-based bio-nanocomposite.

Selective Recognition of Myoglobin in Biological Samples Using Molecularly Imprinted Polymer-Based Affinity Traps

The current work demonstrates the design, characterization, and preparation of molecularly imprinted microspheres for the selective detection of myoglobin in serum samples. The suspension polymerization approach was applied for the preparation of myoglobin imprinted microspheres. For this purpose, N-methacryloylamino folic acid-Nd3+ (MAFol- Nd3+) was chosen as the complex functional monomer. The optimization studies were performed changing the medium pH, temperature, and myoglobin concentration. pH 7.0 was determined as the optimum value where the prepared imprinted microspheres displayed maximum binding for myoglobin. The maximum binding capacity was achieved as 623 mgg-1. In addition, the selectivity studies were conducted. The results confirmed that the imprinted microspheres showed great selectivity towards myoglobin in the existence of hemoglobin, cytochrome c, and lysozyme which were chosen as potentially competing proteins.

Recent progress on the sensitive detection of cardiovascular disease markers by electrochemical-based biosensors

Cardiovascular disease is the most reason for deaths in all over the world. Hence, biomarkers of cardiovascular diseases are very crucial for diagnosis and management process. Biomarker detection demand is opened the important way in biosensor development field. Rapid, cheap, portable, precise, selective and sensitive biomarker sensing devices are needed at this point to detect and predict disease. A cardiac biomarker can be orderable as C-reactive protein, troponin I or T, myoglobin, tumor necrosis factor alpha, interleukin-6, interleukin-1, lipoprotein-associated phospholipase, low-density lipoprotein and myeloperoxidase. They are used for prediction of cardiovascular diseases. There are many methods for early diagnosis of cardiovascular diseases, but these have long time process and expensive devices. In recent studies, different biosensors have been developed to remove the problems in this field. Electrochemical devices and developed biosensors have many superiorities than others such as low cost, mobile, reliable, repeatable, need a little amount of solution. In this review, recent studies were presented as details for cardiovascular disease biomarkers detection using electrochemical methods.

Lab-on-chip technology for chronic disease diagnosis

Various types of chronic diseases (CD) are the leading causes of disability and death worldwide. While those diseases are chronic in nature, accurate and timely clinical decision making is critically required. Current diagnosis procedures are often lengthy and costly, which present a major bottleneck for effective CD healthcare. Rapid, reliable and low-cost diagnostic tools at point-of-care (PoC) are therefore on high demand. Owing to miniaturization, lab-on-chip (LoC) technology has high potential to enable improved biomedical applications in terms of low-cost, high-throughput, ease-of-operation and analysis. In this direction, research toward developing new LoC-based PoC systems for CD diagnosis is fast growing into an emerging area. Some studies in this area began to incorporate digital and mobile technologies. Here we review the recent developments of this area with the focus on chronic respiratory diseases (CRD), diabetes, and chronic kidney diseases (CKD). We conclude by discussing the challenges, opportunities and future perspectives of this field.

An ultrasensitive label free nanobiosensor platform for the detection of cardiac biomarkers

We report the fabrication of a label free nano biosensor platform comprising single nanofiber that is derived out of multi-walled carbon nanotubes (MWCNTs) embedded SU-8 photoresist, for the detection of three important human cardiac biomarkers viz., myoglobin (Myo), cardiac Troponin I (cTn I) and Creatine Kinase-MB (CK-MB). These composite nanofibers were synthesized using electrospinning process. Single nanofibers were aligned between pairs of electrodes in-situ during the electrospinning process. The target proteins were detected using chemiresistive detection methodology. Each biomarker was detected using a specific, single, aligned nanofiber, functionalized with its corresponding monoclonal antibody. Chemiresistive detection involves measuring the change in conductance of the functionalized nanofibers upon the binding of the targeted antigen. The minimum detection limits of Myo, CK-MB and cTn I were experimentally found out to be as low as 6, 20 and 50 fg/ml respectively. No response was observed when the nanofibers were exposed to a non-specific protein, demonstrating excellent specificity to the targeted detection. These MWCNTs embedded SU-8 nanofibers based nanobiosensor platform shows great promise in the detection of cardiac markers and other proteins as they have fast response time, high sensitivity and good specificity.

Graphene-CNT nanohybrid aptasensor for label free detection of cardiac biomarker myoglobin

We report a label free electrochemical detection of cardiac bio-marker myoglobin (Mb) on aptamer functionalized rGO/CNT nanostructured electrodes by measuring its direct electron transfer (DET). Configured as a highly responsive aptasensor, the newly developed biosensing platform exhibits synergistic effect of the nano-hybrid functional construct by combining good electrical properties and the facile chemical functionality of nanohybrid for the compatible bio-interface development. The specific anti-Mb aptamer was generated by five iterative SELEX (Systematic evolution of ligands by exponential enrichment) rounds, showing high senstivity (KD ~65 pM). The aptamer functionalized rGO/CNT nanostructured electrodes demonstrated a significant increase in signal response with a detection limit of ~0.34 ng/mL in the dynamic response range between 1 ng/mL and 4 µg/mL for Mb. The newly developed DET assay format presents a promising candidate in point-of-care diagnosis for routine screening of Mb in patient's samples.

Sensitive point-of-care monitoring of cardiac biomarker myoglobin using aptamer and ubiquitous personal glucose meter

Myoglobin (Myo), which is one of the early markers to increase after acute myocardial infarction (AMI), plays a major role in urgent diagnosis of cardiovascular diseases. Hence, monitoring of Myo in point-of-care is fundamental. Here, a novel assay for sensitive and selective detection of Myo was introduced using a personal glucose meter (PGM) as readout. In the presence of Myo, the anti-Myo antibody immobilized on the surface of polystyrene microplate could capture the target Myo. Then the selected aptamer against Myo, which was obtained using our screening process, was conjugated with invertase, and such aptamer-invertase conjugates bound to the immobilized Myo due to the Myo/aptamer interaction. Subsequently, the resulting "antibody-Myo-aptamer sandwich" complex containing invertase conjugates hydrolyzed sucrose into glucose, thus establishing direct correlation between the Myo concentration and the amount of glucose measured by PGM. By employing the enzyme amplification, as low as 50 pM Myo could be detected. This assay also showed high selectivity for Myo and was successfully used for Myo detection in serum samples. This work may provide a simple but reliable tool for early diagnosis of AMI in the world, especially in developing countries.

Screening of DNA aptamers against myoglobin using a positive and negative selection units integrated microfluidic chip and its biosensing application

An aptamer screening method using a positive and negative selection units integrated microfluidic chip was introduced. Here, myoglobin (Myo), one of the early markers to increase after acute myocardial infarction, was used as the model. After 7-round selection, the aptamers, which exhibited dissociation constants (K(d)) in the nanomolar range (from 4.93 to 6.38 nM), were successfully obtained using a positive and negative selection units integrated microfluidic chip. The aptamer with the highest affinity (K(d) = 4.93 nM) was then used for the fabrication of a label-free supersandwich electrochemical biosensor for Myo detection based on target-induced aptamer displacement. The detection limit of this aptamer-based electrochemical biosensor was 10 pM, which was significantly lower than that of those previous antibody-based biosensors for Myo detection. This work may not only develop a strategy for screening aptamer but also offer promising alternatives to the traditional analytical and immunological methods for Myo detection.

Preparation and optical properties of alloyed Znx Cd1-x S/alginate core/shell nanoparticles

Znx Cd1-x S/alginate core/shell nanoparticles were synthesized via a colloidal route by reacting zinc and cadmium ions with sulfide ions, followed by coating with alginate. The crystal structure, morphology, size and optical properties of the core/shell nanoparticles were characterized by X-ray diffraction, transmission electron microscopy, UV/vis and photoluminescent spectra, respectively. The Znx Cd1-x S nanoparticles are spherical and have a cubic structure with a mean crystalline size of 2-4 nm. The band gap of Znx Cd1-x S/alginate core/shell nanoparticles increases with increasing Zn/Cd molar ratio, and the UV/vis absorption blue-shifts correspondingly. Two emissions related to zinc and sulfide ion vacancies were observed for the Znx Cd1-x S/alginate core/shell nanoparticles due to the surface changes from the alginate coating. A cadmium-related emission was observed for both the uncovered Znx Cd1-x S and Znx Cd1-x S/alginate core/shell nanoparticles, which has a significant blue-shift with increasing Zn/Cd molar ratio.

Cardiovascular disease detection using bio-sensing techniques

Universally, cardiovascular disease (CVD) is recognised as the prime cause of death with estimates exceeding 20 million by 2015 due to heart disease and stroke. Facts regarding the disease, its classification and diagnosis are still lacking. Hence, understanding the issues involved in its initiation, its symptoms and early detection will reduce the high risk of sudden death associated with it. Biosensors developed to be used as rapid screening tools to detect disease biomarkers at the earliest stage and able to classify the condition are revolutionising CVD diagnosis and prognosis. Advances in interdisciplinary research areas have made biosensors faster, highly accurate, portable and environmentally friendly diagnostic devices. The recent advances in microfluidics and the advent of nanotechnology have resulted in the development of improved diagnostics through reduction of analysis time and integration of several clinical assays into a single, portable device as lab-on-a-chip (LOC). The development of such affinity based systems is a major drive of the rapidly growing nanotechnology industry which involves a multidisciplinary research effort encompassing nanofluidics, microelectronics and analytical chemistry. This review summarised the classification of CVD, the biomarkers used for its diagnosis, biosensors and their application including the latest developments in the field of heart-disease detection.

Bio-functionalized Pt nanoparticles based electrochemical impedance immunosensor for human cardiac myoglobin

We report the covalent immobilization of three-dimensional carboxyl-functionalized Pt(MPA) nanoparticles with myoglobin protein antibody by carbodiimide coupling reaction deposited onto an indium-tin-oxide-coated glass plate for the construction of a bioelectrode.

Designing label-free electrochemical immunosensors for cytochrome c using nanocomposites functionalized screen printed electrodes

We have designed here a label-free direct electrochemical immunosensor for the detection of cytochrome c (cyt c), a heme containing metalloprotein using its specific monoclonal antibody. Two nanocomposite-based electrochemical immunosensor platforms were evaluated for the detection of cyt c; (i) self-assembled monolayer (SAM) on gold nanoparticles (GNP) in polypyrrole (PPy) grafted screen printed electrodes (SPE) and (ii) carbon nanotubes (CNT) integrated PPy/SPE. The nanotopologies of the modified electrodes were confirmed by scanning electron microscopy. Electrochemical impedance spectroscopy and cyclic voltammetry were employed to monitor the stepwise fabrication of the nanocomposite immunosensor platforms. In the present method, the label-free quantification of cyt c is based on the direct electron transfer between Fe (III)/Fe (II)-heme redox active site of cyt c selectively bound to anti-cyt c nanocomposite modified SPE. GNP/PPy and CNT/PPy nanocomposites promoted the electron transportation through the conductive pore channels. The overall analytical performance of GNP/PPy based immunosensor (detection limit 2 nM; linear range: 2 nM to 150 µM) was better than the anti-cyt c/CNT/PPy (detection limit 10 nM; linear range: 10 nM to 50 µM). Further, the measurement of cyt c release in cell lysates of cardiomyocytes using the GNP/PPy based immunosensor gave an excellent correlation with standard ELISA.