Voltammetric myoglobin sensor based on a glassy carbon electrode modified with a composite film consisting of carbon nanotubes and a molecularly imprinted polymerized ionic liquid

Point-of-care paper-based analytical device for potentiometric detection of myoglobin as a cardiovascular disease biomarker

One of the cardiac biomarkers, myoglobin (Mb), is important in the rapid identification of cardio-vascular disorders. Therefore, point-of-care monitoring is essential. Pursuing this goal, a robust, reliable, and affordable paper-based analytical apparatus for potentiometric sensing has been developed and characterized. The molecular imprint technique was used to create a customized biomimetic antibody for myoglobin (Mb) on the surface of carboxylated multiwalled carbon nanotubes (MWCNT-COOH). This was accomplished by attaching Mb to carboxylated MWCNTs' surfaces and then filling the empty spaces through the mild polymerization of acrylamide in N,N-methylenebisacrylamide and ammonium persulphate. The modification of the MWCNTs' surface was verified by SEM and FTIR analysis. A hydrophobic paper substrate coated with fluorinated alkyl silane (CF₃(CF₂)₇CH₂CH₂SiCl₃, CF¹⁰) has been coupled with a printed all-solid-state Ag/AgCl reference electrode. The presented sensors showed a linear range of 5.0 × 10^-8 to 1.0 × 10^-4 M with a potentiometric slope of -57.1 ± 0.3 mV decade^-1 (R² = 0.9998) and a detection limit of 28 nM at pH 4. Compared to creatinine, sucrose, fructose, galactose, sodium glutamate, thiamine, alanine, ammonium, uric acid, albumin, glutamine, guanine, troponine T, and glucose, the sensor showed good selectivity for Mb. It demonstrated a good recovery for the detection of Mb in several fake serum samples (93.0-103.3%), with an average relative standard deviation of 4.5%. The current approach might be viewed as a potentially fruitful analytical tool for obtaining disposable, cost-effective paper-based potentiometric sensing devices. These types of analytical devices can be potentially manufacturable at large scales in clinical analysis.

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.

Ionic Liquid-Based Polymer Nanocomposites for Sensors, Energy, Biomedicine, and Environmental Applications: Roadmap to the Future

Current interest toward ionic liquids (ILs) stems from some of their novel characteristics, like low vapor pressure, thermal stability, and nonflammability, integrated through high ionic conductivity and broad range of electrochemical strength. Nowadays, ionic liquids represent a new category of chemical-based compounds for developing superior and multifunctional substances with potential in several fields. ILs can be used in solvents such as salt electrolyte and additional materials. By adding functional physiochemical characteristics, a variety of IL-based electrolytes can also be used for energy storage purposes. It is hoped that the present review will supply guidance for future research focused on IL-based polymer nanocomposites electrolytes for sensors, high performance, biomedicine, and environmental applications. Additionally, a comprehensive overview about the polymer-based composites' ILs components, including a classification of the types of polymer matrix available is provided in this review. More focus is placed upon ILs-based polymeric nanocomposites used in multiple applications such as electrochemical biosensors, energy-related materials, biomedicine, actuators, environmental, and the aviation and aerospace industries. At last, existing challenges and prospects in this field are discussed and concluding remarks are provided.

Fabrication and Characterization of Acute Myocardial Infarction Myoglobin Biomarker Based on Chromium-Doped Zinc Oxide Nanoparticles

In this article, we describe the fabrication and characterization of a sensor for acute myocardial infarction that detects myoglobin biomarkers using chromium (Cr)-doped zinc oxide (ZnO) nanoparticles (NPs). Pure and Cr-doped ZnO NPs (13 × 10¹⁷, 20 × 10¹⁷, and 32 × 10¹⁷ atoms/cm³ in the solid phase) were synthesized by a facile low-temperature sol-gel method. Synthesized NPs were examined for structure and morphological analysis using various techniques to confirm the successful formation of ZnO NPs. Zeta potential was measured in LB media at a negative value and increased with doping. XPS spectra confirmed the presence of oxygen deficiency in the synthesized material. To fabricate the sensor, synthesized NPs were screen-printed over a pre-fabricated gold-coated working electrode for electrochemical detection of myoglobin (Mb). Cr-doped ZnO NPs doped with 13 × 10¹⁷ Cr atomic/cm³ revealed the highest sensitivity of ~37.97 μA.cm⁻²nM⁻¹ and limit of detection (LOD) of 0.15 nM for Mb with a response time of ≤10 ms. The interference study was carried out with cytochrome c (Cyt-c) due to its resemblance with Mb and human serum albumin (HSA) abundance in the blood and displayed distinct oxidation potential and current values for Mb. Cr-doped ZnO NP-based Mb biosensors showed 3 times higher sensitivity as compared to pure ZnO NP-based sensors.

Electrochemical sensing of macromolecules based on molecularly imprinted polymers: challenges, successful strategies, and opportunities

Looking at the literature focused on molecularly imprinted polymers (MIPs) for protein, it soon becomes apparent that a remarkable increase in scientific interest and exploration of new applications has been recorded in the last several years, from 42 documents in 2011 to 128 just 10 years later, in 2021 (Scopus, December 2021). Such a rapid threefold increase in the number of works in this field is evidence that the imprinting of macromolecules no longer represents a distant dream of optimistic imprinters, as it was perceived until only a few years ago, but is rapidly becoming an ever more promising and reliable technology, due to the significant achievements in the field. The present critical review aims to summarize some of them, evidencing the aspects that have contributed to the success of the most widely used strategies in the field. At the same time, limitations and drawbacks of less frequently used approaches are critically discussed. Particular focus is given to the use of a MIP for protein in the assembly of electrochemical sensors. Sensor design indeed represents one of the most active application fields of imprinting technology, with electrochemical MIP sensors providing the broadest spectrum of protein analytes among the different sensor configurations.

Electroanalytical point-of-care detection of gold standard and emerging cardiac biomarkers for stratification and monitoring in intensive care medicine - a review

Determination of specific cardiac biomarkers (CBs) during the diagnosis and management of adverse cardiovascular events such as acute myocardial infarction (AMI) has become commonplace in emergency department (ED), cardiology and many other ward settings. Cardiac troponins (cTnT and cTnI) and natriuretic peptides (BNP and NT-pro-BNP) are the preferred biomarkers in clinical practice for the diagnostic workup of AMI, acute coronary syndrome (ACS) and other types of myocardial ischaemia and heart failure (HF), while the roles and possible clinical applications of several other potential biomarkers continue to be evaluated and are the subject of several comprehensive reviews. The requirement for rapid, repeated testing of a small number of CBs in ED and cardiology patients has led to the development of point-of-care (PoC) technology to circumvent the need for remote and lengthy testing procedures in the hospital pathology laboratories. Electroanalytical sensing platforms have the potential to meet these requirements. This review aims firstly to reflect on the potential benefits of rapid CB testing in critically ill patients, a very distinct cohort of patients with deranged baseline levels of CBs. We summarise their source and clinical relevance and are the first to report the required analytical ranges for such technology to be of value in this patient cohort. Secondly, we review the current electrochemical approaches, including its sub-variants such as photoelectrochemical and electrochemiluminescence, for the determination  of important CBs highlighting the various strategies used, namely the use of micro- and nanomaterials, to maximise the sensitivities and selectivities of such approaches. Finally, we consider the challenges that must be overcome to allow for the commercialisation of this technology and transition into intensive care medicine.

Novel electrochemical sensor modified with molecularly imprinted polymers for determination of enrofloxacin in marine environment

Molecularly imprinted polymers were synthesized by gel-sol method with multi-walled carbon nanotubes as support and enrofloxacin as a template and further modified on the surface of glassy carbon electrode to construct a molecularly imprinted electrochemical sensor. The performance of the imprinted electrochemical sensor was thoroughly investigated by using cyclic voltammetry and differential pulse voltammetry. The influence of imprinted polymers amount, electrolyte pH, and incubation time on the sensor performance was investigated for the detection of enrofloxacin. Under the optimal experimental conditions in a three-electrode system with the modified electrode as the working electrode the differential pulse voltammetry response current of the sensor had a good linear relationship at 0.2 V (vs. saturated calomel reference electrode) with the enrofloxacin concentration within 2.8 pM-28 μM and the limit of detection of the method was 0.9 pM. The competitive interference experiment showed that the imprinted electrochemical sensor could selectively recognize enrofloxacin. The method was applied to analyze spiked natural seawater, fish, and shrimp samples. The recovery was 96.4%-102%, and RSD was less than 4.3% (n = 3), indicating that the proposed imprinted electrochemical sensor was suitable for the determination of trace enrofloxacin in marine environment samples.

Graphene Quantum Dots-Based Electrochemical Biosensing Platform for Early Detection of Acute Myocardial Infarction

Heart failure resulting from acute myocardial infarction (AMI) is an important global health problem. Treatments of heart failure and AMI have improved significantly over the past two decades; however, the available diagnostic tests only give limited insights into these heterogeneous conditions at a reversible stage and are not precise enough to evaluate the status of the tissue at high risk. Innovative diagnostic tools for more accurate, more reliable, and early diagnosis of AMI are urgently needed. A promising solution is the timely identification of prognostic biomarkers, which is crucial for patients with AMI, as myocardial dysfunction and infarction lead to more severe and irreversible changes in the cardiovascular system over time. The currently available biomarkers for AMI detection include cardiac troponin I (cTnI), cardiac troponin T (cTnT), myoglobin, lactate dehydrogenase, C-reactive protein, and creatine kinase and myoglobin. Most recently, electrochemical biosensing technologies coupled with graphene quantum dots (GQDs) have emerged as a promising platform for the identification of troponin and myoglobin. The results suggest that GQDs-integrated electrochemical biosensors can provide useful prognostic information about AMI at an early, reversible, and potentially curable stage. GQDs offer several advantages over other nanomaterials that are used for the electrochemical detection of AMI such as strong interactions between cTnI and GQDs, low biomarker consumption, and reusability of the electrode; graphene-modified electrodes demonstrate excellent electrochemical responses due to the conductive nature of graphene and other features of GQDs (e.g., high specific surface area, π-π interactions with the analyte, facile electron-transfer mechanisms, size-dependent optical features, interplay between bandgap and photoluminescence, electrochemical luminescence emission capability, biocompatibility, and ease of functionalization). Other advantages include the presence of functional groups such as hydroxyl, carboxyl, carbonyl, and epoxide groups, which enhance the solubility and dispersibility of GQDs in a wide variety of solvents and biological media. In this perspective article, we consider the emerging knowledge regarding the early detection of AMI using GQDs-based electrochemical sensors and address the potential role of this sensing technology which might lead to more efficient care of patients with AMI.

Carbon Nanotube (CNT)-Based Biosensors

This review focuses on recent advances in the application of carbon nanotubes (CNTs) for the development of sensors and biosensors. The paper discusses various configurations of these devices, including their integration in analytical devices. Carbon nanotube-based sensors have been developed for a broad range of applications including electrochemical sensors for food safety, optical sensors for heavy metal detection, and field-effect devices for virus detection. However, as yet there are only a few examples of carbon nanotube-based sensors that have reached the marketplace. Challenges still hamper the real-world application of carbon nanotube-based sensors, primarily, the integration of carbon nanotube sensing elements into analytical devices and fabrication on an industrial scale.

Advances in point-of-care testing for cardiovascular diseases

Point-of-care testing (POCT) is a specific format of diagnostic testing that is conducted without accompanying infrastructure or sophisticated instrumentation. Traditionally, such rapid sample-to-answer assays provide inferior analytical performances to their laboratory counterparts when measuring cardiac biomarkers. Hence, their potentially broad applicability is somewhat bound by their inability to detect clinically relevant concentrations of cardiac troponin (cTn) in the early stages of myocardial injury. However, the continuous refinement of biorecognition elements, the optimization of detection techniques, and the fabrication of tailored fluid handling systems to manage the sensing process has stimulated the production of commercial assays that can support accelerated diagnostic pathways. This review will present the latest commercial POC assays and examine their impact on clinical decision-making. The individual elements that constitute POC assays will be explored, with an emphasis on aspects that contribute to economically feasible and highly sensitive assays. Furthermore, the prospect of POCT imparting a greater influence on early interventions for medium to high-risk individuals and the potential to re-shape the paradigm of cardiovascular risk assessments will be discussed.

A Disposable Saliva Electrochemical MIP-Based Biosensor for Detection of the Stress Biomarker α-Amylase in Point-of-Care Applications

The design and synthesis of artificial receptors based on molecular imprinting (MI) technology for the development of a new MIP-based biosensor for detection of the stress biomarker α-amylase in human saliva in point-of-care (PoC) applications is described in this work. The portable electrochemical devices for monitoring α-amylase consists of cost-effective and disposable gold screen-printed electrodes (AuSPEs). To build the electrochemical device, the template biomolecule was firstly immobilized directly over the working area of the gold chip previously activated with a self-assembled monolayer (SAM) of cysteamine (CA). Then, pyrrole (Py) monomer was selected as building block of a polymeric network prepared by CV electropolymerization. After the electropolymerization process, the enzyme was removed from the polymer film in order to build the specific recognition sites for the target enzyme. The MIP biosensor showed a very wide linear concentration range (between 3.0 × 10−4 to 0.60 mg mL−1 in buffer solution and between 3.0 × 10−4 to 3.0 × 10−2 mg mL−1 in human saliva) and low detection levels were achieved (LOD < 3.0 × 10−4 mg mL−1) using square wave voltammetry (SWV) as the electroanalytical technique.

Label-Free Electrochemical Sensor Based on Manganese Doped Titanium Dioxide Nanoparticles for Myoglobin Detection: Biomarker for Acute Myocardial Infarction

A label free electrochemical sensor based on pure titanium oxide and manganese (Mn)-doped titanium oxide (TiO2) nanoparticles are fabricated and characterized for the sensitive detection of myoglobin (Mb) levels to analyze the cardiovascular infarction. Pristine and Mn-doped TiO2 nanoparticles were synthesized via the sol-gel method and characterized in order to understand their structure, morphologies, composition and optical properties. The structural properties revealed that the pure- and doped-TiO2 nanoparticles possess different TiO2 planes. FTIR studies confirm the formation of metal oxide nanoparticles by exhibiting a well-defined peak in the range of 600-650 cm-1. The values of the optical band gap, estimated from UV-Vis spectroscopy, are decreased for the Mn-doped TiO2 nanoparticles. UV-Vis spectra in the presence of myoglobin (Mb) indicated interaction between the TiO2 nanoparticles and myoglobin. The SPE electrodes were then fabricated by printing powder film over the working electrode and tested for label-free electrochemical detection of myoglobin (Mb) in the concentration range of 0-15 nM Mb. The fabricated electrochemical sensor exhibited a high sensitivity of 100.40 μA-cm-2/nM with a lowest detection limit of 0.013 nM (0.22 ng/mL) and a response time of ≤10 ms for sample S3. An interference study with cyt-c and Human Serum Albumin (HSA) of the sensors show the selective response towards Mb in 1:1 mixture.

Recent Trends in Electrochemical Sensors for Vital Biomedical Markers Using Hybrid Nanostructured Materials

This work provides a succinct insight into the recent developments in electrochemical quantification of vital biomedical markers using hybrid metallic composite nanostructures. After a brief introduction to the biomarkers, five types of crucial biomarkers, which require timely and periodical monitoring, are shortlisted, namely, cancer, cardiac, inflammatory, diabetic and renal biomarkers. This review emphasizes the usage and advantages of hybrid nanostructured materials as the recognition matrices toward the detection of vital biomarkers. Different transduction methods (fluorescence, electrophoresis, chemiluminescence, electrochemiluminescence, surface plasmon resonance, surface-enhanced Raman spectroscopy) reported for the biomarkers are discussed comprehensively to present an overview of the current research works. Recent advancements in the electrochemical (amperometric, voltammetric, and impedimetric) sensor systems constructed with metal nanoparticle-derived hybrid composite nanostructures toward the selective detection of chosen vital biomarkers are specifically analyzed. It describes the challenges involved and the strategies reported for the development of selective, sensitive, and disposable electrochemical biosensors with the details of fabrication, functionalization, and applications of hybrid metallic composite nanostructures.

An imprinted polymeric matrix containing DNA for electrochemical sensing of 2,4-dichlorophenoxyacetic acid

The authors describe an electrochemical method for the determination of herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). It is based on the use of a molecularly imprinted polymer (MIP) and of dsDNA as a bio-specific substance. The modified electrode was prepared by electropolymerization of ortho-phenylenediamine (oPD) in the presence of DNA and of 2,4-D (the template). The imprinted MIP was placed on a pencil graphite electrode (PGE) modified with chitosan and multiwalled carbon nanotubes (MWCNTs). The template was removed with 0.4 M NaOH. The interaction of DNA with 2,4-D leads to its adsorption on the electrode, and this increases the sensitivity and selectivity of the method. After rebinding 2,4-D, the decrease in the peak current of oxidation of iron(II) acting as an electrochemical redox probe was measured by differential pulse voltammetry (DPV). The current, typically measured at around 0.5 V, increases linearly in the 0.01 to 10 pM 2,4-D concentration range, and the detection limit is 4.0 fM. The method is highly selective for 2,4-D. The modified electrode was applied to quantify 2,4-D in spiked environmental water and soil samples and gave absolute recoveries varying from 91.5 to 109.0%. Graphical abstractSchematic representation of the fabrication of an electrochemical sensor for determination of 2,4-dichlorophenoxyacetic acid (2,4-D). Initially, the electrode was modified with chitosan and MWCNTs and then a composite was formed on it consisting of ortho-phenylenediamine (oPD), DNA and 2,4-D.

Evaluation of Molecularly Imprinted Polymers for Point-of-Care Testing for Cardiovascular Disease

Molecular imprinting is a rapidly growing area of interest involving the synthesis of artificial recognition elements that enable the separation of analyte from a sample matrix and its determination. Traditionally, this approach can be successfully applied to small analyte (<1.5 kDa) separation/ extraction, but, more recently it is finding utility in biomimetic sensors. These sensors consist of a recognition element and a transducer similar to their biosensor counterparts, however, the fundamental distinction is that biomimetic sensors employ an artificial recognition element. Molecularly imprinted polymers (MIPs) employed as the recognition elements in biomimetic sensors contain binding sites complementary in shape and functionality to their target analyte. Despite the growing interest in molecularly imprinting techniques, the commercial adoption of this technology is yet to be widely realised for blood sample analysis. This review aims to assess the applicability of this technology for the point-of-care testing (POCT) of cardiovascular disease-related biomarkers. More specifically, molecular imprinting is critically evaluated with respect to the detection of cardiac biomarkers indicative of acute coronary syndrome (ACS), such as the cardiac troponins (cTns). The challenges associated with the synthesis of MIPs for protein detection are outlined, in addition to enhancement techniques that ultimately improve the analytical performance of biomimetic sensors. The mechanism of detection employed to convert the analyte concentration into a measurable signal in biomimetic sensors will be discussed. Furthermore, the analytical performance of these sensors will be compared with biosensors and their potential implementation within clinical settings will be considered. In addition, the most suitable application of these sensors for cardiovascular assessment will be presented.

Electrochemical Sensing of α-Fetoprotein Based on Molecularly Imprinted Polymerized Ionic Liquid Film on a Gold Nanoparticle Modified Electrode Surface

A molecularly imprinted sensor was fabricated for alpha-fetoprotein (AFP) using an ionic liquid as a functional monomer. Ionic liquid possesses many excellent characteristics which can improve the sensing performances of the imprinted electrochemical sensor. To demonstrate this purpose, 1-[3-(N-cystamine)propyl]-3-vinylimidazolium tetrafluoroborate ionic liquid [(Cys)VIMBF₄] was synthesized and used as a functional monomer to fabricate an AFP imprinted polymerized ionic liquid film on a gold nanoparticle modified glassy carbon electrode (GCE) surface at room temperature. After removing the AFP template, a molecularly imprinted electrochemical sensor was successfully prepared. The molecularly imprinted sensor exhibits excellent selectivity towards AFP, and can be used for sensitive determination of AFP. Under the optimized conditions, the imprinted sensor shows a good linear response to AFP in the concentration range of 0.03 ng mL⁻¹~5 ng mL⁻¹. The detection limit is estimated to be 2 pg mL⁻¹.

Dual-modality impedimetric immunosensor for early detection of prostate-specific antigen and myoglobin markers based on antibody-molecularly imprinted polymer

A new dual-modality immunosensor based on molecularly imprinted polymer (MIP) and a nanostructured biosensing layer has fabricated for the simultaneous detection of two important markers including prostate-specific antigen (PSA) and myoglobin (Myo) in human serum and urine samples. In the first step, 3,3'-dithiodipropionic acid di(N-hydroxysuccinimide ester) (DSP) was self-assembled on a gold screen printed electrode (SPE). Then, the target proteins were attached covalently to the DSP-SPE. The imprinted cocktail polymer ((MIP(PSA, Myo)-SPE)) was synthesized at the SPE surface using acrylamide as monomer, N,N'-methylenebisacrylamide as a crosslinker, and PSA and Myo as the templates, respectively. The MIP-SPE was specific for the impedimetric sensing of PSA and Myo. After that, a nanocomposite (NCP) was synthesized based on the decorated magnetite nanoparticles with multi-walled carbon nanotube, graphene oxide and specific antibody for PSA (Ab). Then, NCP incubated with (MIP(PSA, Myo)-SPE. The modified electrodes and synthesized nanoparticles were characterized using electrochemical impedance spectroscopy, dynamic light scattering, surface plasmon resonance and scanning electron microscopy. The limits of detections were found to be 5.4 pg mL^-1 and 0.83 ng mL^-1 with the linear dynamic ranges of 0.01-100 and 1-20000 ng mL^-1 for PSA and Myo, respectively. The ability of proposed biosensor to detect PSA and Myo simultaneously with high sensitivity and specificity offers a powerful opportunity for the new generation of biosensors. This dual-analyte specific receptors-based device is highly desired for the integration with lab-on-chip kits to measure a wide panel of biomarkers present at ultralow levels during early stages of diseases progress.

Stimuli-enabled switch-like paracetamol electrochemical sensor based on thermosensitive polymer and MWCNTs-GQDs composite nanomaterial

A temperature-controlled switchable electrochemical sensor was constructed based on a composite film consisting of thermosensitive block polymer poly(styrene-b-(N-isopropylacrylamide)-b-styrene) (PS-PNIPAm-PS), carboxylated multi-walled carbon nanotubes (MWCNTs-COOH) and amino-functionalized graphene quantum dots (N-GQDs). The prepared sensor showed good temperature sensitivity and reversibility in sensing paracetamol. In the low temperature environment, the polymer stretched to bury the electroactive sites of the carbon nanocomposite, and the paracetamol could not pass through the polymer to achieve electronic exchange, representing the "closed" state. Conversely, in the high temperature environment, the polymer shrank to expose the electroactive sites and enlarge background currents, the paracetamol was able to undergo the redox reaction normally and generate the response current, representing the "on" state. In addition, the sensor had a wide detection range (0.1 to 7.0 μM and 7.0 to 103.0 μM) and a low LOD of 66 nM for paracetamol. This switch-like sensor provided a novel idea for the application of thermosensitive polymers.

Molecularly Imprinted Polymer Based Sensors for Medical Applications

Sensors have been extensively used owing to multiple advantages, including exceptional sensing performance, user-friendly operation, fast response, high sensitivity and specificity, portability, and real-time analysis. In recent years, efforts in sensor realm have expanded promptly, and it has already presented a broad range of applications in the fields of medical, pharmaceutical and environmental applications, food safety, and homeland security. In particular, molecularly imprinted polymer based sensors have created a fascinating horizon for surface modification techniques by forming specific recognition cavities for template molecules in the polymeric matrix. This method ensures a broad range of versatility to imprint a variety of biomolecules with different size, three dimensional structure, physical and chemical features. In contrast to complex and time-consuming laboratory surface modification methods, molecular imprinting offers a rapid, sensitive, inexpensive, easy-to-use, and highly selective approaches for sensing, and especially for the applications of diagnosis, screening, and theranostics. Due to its physical and chemical robustness, high stability, low-cost, and reusability features, molecularly imprinted polymer based sensors have become very attractive modalities for such applications with a sensitivity of minute structural changes in the structure of biomolecules. This review aims at discussing the principle of molecular imprinting method, the integration of molecularly imprinted polymers with sensing tools, the recent advances and strategies in molecular imprinting methodologies, their applications in medical, and future outlook on this concept.

Recent uses of carbon nanotubes & gold nanoparticles in electrochemistry with application in biosensing: A review

The innovation of nanoparticles assumes a critical part of encouraging and giving open doors and conceivable outcomes to the headway of new era devices utilized as a part of biosensing. The focused on the quick and legitimate detecting of specific biomolecules using functionalized gold nanoparticles (Au NPs), and carbon nanotubes (CNTs) has turned into a noteworthy research enthusiasm for the most recent decade. Sensors created with gold nanoparticles or carbon nanotubes or in some cases by utilizing both are relied upon to change the very establishments of detecting and distinguishing various analytes. In this review, we will examine the current utilization of functionalized AuNPs and CNTs with other synthetic mixes for the creation of biosensor prompting to the location of particular analytes with low discovery cutoff and quick reaction.

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.

Nanostructured aptamer-based sensing platform for highly sensitive recognition of myoglobin

A composite was prepared from PtSn nanoparticles and carbon nanotubes (PtSnNP/CNTs) and applied to the electrochemical determination of myoglobin (Mb). An Mb-aptamer was immobilized on a glassy carbon electrode (GCE), and hexcyanoferrate was used as an electrochemical probe. The PtSnNP/CNTs were synthesized by a microwave-aided ethylene glycol reduction method. Detection is based on electron transfer inhibition that is caused by the folding and conformational change of the Mb-aptamer in the presence of Mb. The amperometric signal for hexacyanoferrate, best measured at 0.2 V vs. Ag/AgCl depends on the concentration of Mb that interacts with the aptamer on the GCE. This approach is selective and sensitive for Mb due to (a) the highly specific recognition ability of the aptamer for Mb, (b) the powerful electronic properties of carbon nanotubes, (c) the arranged decoration of CNTs with PtSnNPs, and (d), the superior electron transfer to hexacyanoferrate. The assay is highly selective, with linear relationships from 0.01-1 nM and 10 nM-200 nM, and a limit of detection as low as 2.2 ± 0.1 pM. The modified GCE was applied to the quantitation of Mb in spiked human serum samples. Graphical abstract Schematic illustration of the method for Mb detection.

Plasmonic DNA hotspots made from tungsten disulfide nanosheets and gold nanoparticles for ultrasensitive aptamer-based SERS detection of myoglobin

A nanohybrid mediated SERS substrate was prepared by in-situ synthesis and assembly of gold nanoparticles (AuNPs) on exfoliated nanosheets of tungsten disulfide (WS₂) to form plasmonic hotspots. The nanohybrid surface was functionalized with specific aptamers which imparted high selectivity for the cardiac marker myoglobin (Mb). The fabricated aptasensor was read by SERS using a 532 nm laser and demonstrated significant signal enhancement, and this allowed Mb to be determined in the 10 f. mL^-1 to 0.1 μg mL^-1 concentration range. The study presents an approach to synergistically exploit the unique chemical and electromagnetic properties of both WS₂ and AuNPs for many-fold enhancement of SERS signals. Graphical abstract Schematic presentation of a nanohybrid-mediated SERS substrate prepared by in-situ assembly of gold nanoparticles (AuNPs) reduced on exfoliated nanosheets of tungsten disulfide (WS₂) to form plasmonic hot spots. Specific aptamers immobilized on the SERS surface impart high sensitivity and selectivity for the cardiac marker myoglobin (Mb).

Voltammetric sensing based on the use of advanced carbonaceous nanomaterials: a review

This review (with 210 references) summarizes recent developments in the design of voltammetric chemical sensors and biosensors based on the use of carbon nanomaterials (CNMs). It is divided into subsections starting with an introduction into the field and a description of its current state. This is followed by a large section on various types of voltammetric sensors and biosensors using CNMs with subsections on sensors based on the use of carbon nanotubes, graphene, graphene oxides, graphene nanoribbons, fullerenes, ionic liquid composites with CNMs, carbon nanohorns, diamond nanoparticles, carbon dots, carbon nanofibers and mesoporous carbon. The third section gives conclusion and an outlook. Tables are presented on the application of such sensors to voltammetric detection of neurotransmitters, metabolites, dietary minerals, proteins, heavy metals, gaseous molecules, pharmaceuticals, environmental pollutants, food, beverages, cosmetics, commercial goods and drugs of abuse. The authors also describe advanced approaches for the fabrication of robust functional carbon nano(bio)sensors for voltammetric quantification of multiple targets. Graphical Abstract Featuring execellent electrical, catalytic and surface properies, CNMs have gained enormous attention for designing voltammetric sensors and biosensors. Functionalized CNM-modified electrode interfaces have demonstrated their prominent role in biological, environmental, pharmaceutical, chemical, food and industrial analysis.

A fluorescence switch sensor for detection of virginiamycin based on graphene oxide-supported carbon quantum dots and molecularly imprinted polymer

A fluorescence switch sensor was developed for the detection of virginiamycin, which was based on graphene oxide-supported carbon quantum dots (GO/C-dots) as the signal indicator and molecularly imprinted polymer (MIP) as the recognition template.