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

Metallic nanostructure-based aptasensors for robust detection of proteins

There is a significant need for fast, cost-effective, and highly sensitive protein target detection, particularly in the fields of food, environmental monitoring, and healthcare. The integration of high-affinity aptamers with metal-based nanomaterials has played a crucial role in advancing the development of innovative aptasensors tailored for the precise detection of specific proteins. Aptamers offer several advantages over commonly used molecular recognition methods, such as antibodies. Recently, a variety of metal-based aptasensors have been established. These metallic nanomaterials encompass noble metal nanoparticles, metal oxides, metal-carbon nanotubes, carbon quantum dots, graphene-conjugated metallic nanostructures, as well as their nanocomposites, metal-organic frameworks (MOFs), and MXenes. In general, these materials provide enhanced sensitivity through signal amplification and transduction mechanisms. This review primarily focuses on the advancement of aptasensors based on metallic materials for the highly sensitive detection of protein targets, including enzymes and growth factors. Additionally, it sheds light on the challenges encountered in this field and outlines future prospects. We firmly believe that this review will offer a comprehensive overview and fresh insights into metallic nanomaterials-based aptasensors and their capabilities, paving the way for the development of innovative point-of-care (POC) diagnostic devices.

Recent advancements of nanomodified electrodes - Towards point-of-care detection of cardiac biomarkers

The increasing number of deaths from cardiovascular diseases has become a substantial concern in both developed and underdeveloped countries. Rapid and on-site monitoring of this disease is urgently important to control, prevent and make awareness of public health. Recently, a lot of focus has been placed on nanomaterials and modify these nanomaterials have been explored to detect cardiac biomarkers. By implementing biosensors that are modified with novel recognition elements and more stable nanomaterials, the use of electrochemistry for point-of-care devices is more realistic every day. This review focuses on the current state of nanomaterials conjugated biorecognition elements (enzyme integrated with nanomaterials, antibody conjugated nanomaterials and aptamer conjugated nanomaterials) for electrochemical cardiovascular disease detection. Specifically, a lot of attention has been given to the trends toward more stable biosensors that have increased the potential to be used as point-of-care devices for the detection of cardiac biomarkers due to their high stability and specificity. Moreover, the recent progress on biomolecule-free electrochemical nanosensors for cardiovascular disease detection has been considered. At last, the possibility and drawbacks of some of these techniques for point-of-care cardiac device development in the future have been discussed.

Real-Time Intracellular Analysis of Kanamycin Using Microaptasensors

With the emergence of multidrug-resistant bacteria, infection-related death toll is on the rise. Overuse of antibiotics and their leakage into waterways have transformed the environment into a sink, resulting in bacterial resistance permeating through all tiers of the food cycle. As one of the primary sources of food, fish and fish products such as fish eggs must be studied for their ability to accumulate relevant antibiotics. While the accumulation of these pharmaceuticals has previously been studied, there remains a need to analyze these processes in real time. Electrochemical aptamer-based sensor technology allows for selective, real-time monitoring of small molecules. Herein, we report the first use of miniaturized electrochemical aptamer-based sensors for the analysis of the passive uptake of the aminoglycoside antibiotic, kanamycin, in single salmon eggs. We use pulled platinum microelectrodes and increase the surface area at the electrode tip through dendritic gold deposition. These electrodes showed a 100-fold increase in DNA immobilization on the electrode surface as compared to bare microelectrodes. Additionally, the sensors showed improved stability in complex biological media over an extended period of time when compared to the more widely used macrosensors (r = 1 mm). The sensor range was determined to extend from nanomolar to micromolar concentrations of kanamycin in fish egg lysate and when used in a single salmon egg the μ-aptasensors were able to monitor the passive uptake of kanamycin over time. The accumulation kinetics were simulated using COMSOL Multiphysics software. This research presents the first reported record of passive uptake of a small molecule in a single cell in real-time using electrochemistry.

A Review on Aptamers Selection and Application in Heart Diseases Diagnosis

Biomarkers detection and quantification in biological fluids play a key role in the screening, diagnosing and treating several diseases. Recently, a large number of aptamers have been selected and applied for the sensing of different biomarkers. Combined with different transducers, aptamers provide simple and rapid tools that allow highly sensitive and selective detection. Cardiology requires an accurate assessment of cardiac biomarkers for a complete diagnosis of cardiovascular diseases. The analysis is generally performed by immunoassays using antibodies as biorecognition elements. This review paper focuses on using aptamers as a promising alternative for antibodies in cardiac biomarkers biosensing. First, the different aptamers specific to the most important cardiac biomarkers are Troponin I, the peptide of B-type natriuretic peptide and myoglobin. Then, in the second part, we overview the electrochemical aptasensors principle and characteristics reported in the literature in the last five years.

Aptamer-based applications for cardiovascular disease

Cardiovascular disease (especially atherosclerosis) is a major cause of death worldwide, and novel diagnostic tools and treatments for this disease are urgently needed. Aptamers are single-stranded oligonucleotides that specifically recognize and bind to the targets by forming unique structures in vivo, enabling them to rival antibodies in cardiac applications. Chemically synthesized aptamers can be readily modified in a site-specific way, so they have been engineered in the diagnosis of cardiac diseases and anti-thrombosis therapeutics. Von Willebrand Factor plays a unique role in the formation of thrombus, and as an aptamer targeting molecule, has shown initial success in antithrombotic treatment. A combination of von Willebrand Factor and nucleic acid aptamers can effectively inhibit the progression of blood clots, presenting a positive diagnosis and therapeutic effect, as well as laying a novel theory and strategy to improve biocompatibility paclitaxel drug balloon or implanted stent in the future. This review summarizes aptamer-based applications in cardiovascular disease, including biomarker discovery and future management strategy. Although relevant applications are relatively new, the significant advancements achieved have demonstrated that aptamers can be promising agents to realize the integration of diagnosis and therapy in cardiac research.

Nanomaterial-based sandwich-type electrochemical aptasensor platform for sensitive voltammetric determination of leptin

A sandwich-type electrochemical aptasensor was designed for sensitive detection of leptin in biological samples, including human serum and human plasma. The developed aptasensor was produced by electrodeposition of gold nanoparticles on a screen-printed electrode modified with zinc oxide nanoparticles. The synergy effect of zinc oxide and gold nanoparticles improved the electrocatalytic activity of the aptasensor. The obtained high surface area allowed more aptamer molecules to be loaded on the electrode surface. Signal amplification significantly increases the detection sensitivity of a developed biosensor. Although the use of nanomaterials is the most preferred detection tool for this purpose, as an alternative, enzyme-catalyzed signal amplification is widely used in the construction of a biosensor due to its specificity and high catalytic efficiency. Therefore, both nanomaterial-supported and an alkaline phosphatase-based aptasensor design were developed, which can produce in situ electroactive product by enzymatic hydrolysis of the inactive substrate to achieve a higher signal-to-background ratio. Under optimal conditions, the developed aptasensor exhibited a wide linear concentration range from 0.01 pg mL^-1 to 100.0 pg mL^-1 with a detection limit of 0.0035 pg mL^-1. While the developed aptasensor provided excellent selectivity in the presence of some interfering compounds, it possessed outstanding reproducibility and stability. In addition, the developed aptasensor has been applied with good recoveries in the range 96.31 to 108.79% in human serum and plasma samples. In conclusion, all the obtained results showed the feasibility of the developed aptasensor for practical applications.

Nanomaterial-based aptasensors as an efficient substitute for cardiovascular disease diagnosis: Future of smart biosensors

As a major cause of deaths in developed countries, cardiovascular disease (CVD) has been a big burden for human health systems. Its early and rapid detection is crucial to efficiently apply appropriate on time therapy and to ultimately reduce the associated mortality rate. Aptamers, known as single-stranded DNA/RNA or oligonucleotides containing receptors and/or catalytic properties, have been widely employed in biodetection platforms due to their beneficial properties. Like antibodies, aptamers have served as artificial target receptors in affinity biosensors. Currently, advanced biosensors with improved sensitivity and specificity are fabricated by the synergistic combination of aptamers and diverse nanomaterials. Herein, we review the current development and applications of nanomaterial-based aptasensors for the recognition of CVD biomarkers with special emphasis on electrochemical and optical technologies. The performance of aptasensors has been assessed further in terms of key quality assurance metrics along with discussions on recent technologies developed for the amplification of signals with enhanced portability.

Electrochemical Aptasensors: Current Status and Future Perspectives

This article reviews the progress of diversity of electrochemical aptasensor for target analytes detection. The immobilization strategies of aptamers on an electrode surface are addressed. The aptasensors are also introduced in compliance with the assay platforms. Many electrochemical aptasensors are nearly identical to conventional immunochemical approaches, sandwich and competition assays using electroactive signaling moieties. Others are "signal-on" and "sign-off" aptasensors credited to the target binding-induced conformational change of aptamers. Label-free aptasensors are also highlighted. Furthermore, the aptasensors applied for clinically important biomarkers are emphasized.

Advances in Electrochemical Aptasensors Based on Carbon Nanomaterials

Carbon nanomaterials offer unique opportunities for the assembling of electrochemical aptasensors due to their high electroconductivity, redox activity, compatibility with biochemical receptors and broad possibilities of functionalization and combination with other auxiliary reagents. In this review, the progress in the development of electrochemical aptasensors based on carbon nanomaterials in 2016–2020 is considered with particular emphasis on the role of carbon materials in aptamer immobilization and signal generation. The synthesis and properties of carbon nanotubes, graphene materials, carbon nitride, carbon black particles and fullerene are described and their implementation in the electrochemical biosensors are summarized. Examples of electrochemical aptasensors are classified in accordance with the content of the surface layer and signal measurement mode. In conclusion, the drawbacks and future prospects of carbon nanomaterials’ application in electrochemical aptasensors are briefly discussed.

Fluorescent aptasensor based on D-AMA/F-CSC for the sensitive and specific recognition of myoglobin

A novel fluorescent biosensor based on dabcyl [(E)-4-((4-(dimethylamino) phenyl) diazenyl)benzoic acid] -modified anti-Mb aptamer (D-AMA) and 6-FAM(6-carboxyfluorescein) -modified complementary short chain (F-CSC)for the specific and sensitive detection of Mb levels is presented in this study. In PBS buffer solution, D-AMA bound to F-CSC, and then dabcyl quenched the fluorescence of 6-FAM. After adding Mb into the system, D-AMA bound to Mb and separated from F-CSC. The fluorescence of 6-FAM was restored after it separated from dabcyl. The assay exhibited high specificity and sensitivity toward Mb, with a low limit of detection of 0.07 ng/mL (S/N = 3) and linear relationships of 0.1-5 ng/mL. It was further applied to detect Mb levels in spiked human blood sera samples.

Aptamers in nanostructure-based electrochemical biosensors for cardiac biomarkers and cancer biomarkers: A review

Heart disease (especially myocardial infarction (MI)) and cancer are major causes of death. Recently, aptasensors with the applying of different nanostructures have been able to provide new windows for the early and inexpensive detection of these deadly diseases. Early, inexpensive, and accurate diagnosis by portable devices, especially aptasensors can increase the likelihood of survival as well as significantly reduce the cost of treatment. In this review, recent studies based on the designed aptasensors for the diagnosis of these diseases were collected, ordered, and reviewed. The biomarkers for the diagnosis of each disease were discussed separately. The primary constituent elements of these aptasensors including, analyte, aptamer sequence, type of nanostructure, diagnostic technique, analyte detection range, and limit of detection (LOD), were evaluated and compared.

Fluorometric determination of cardiac myoglobin based on energy transfer from a pyrene-labeled aptamer to graphene oxide

The authors describe a fluorometric assay for cardiac myoglobin (Mb), a marker for myocardial infarction. An Mb-binding aptamer was labeled with pyrene and adsorbed on the surface of graphene oxide (GO) via noncovalent and reversible binding forces. This causes the fluorescence of pyrene (best measured at excitation/emission wavelengths of 275/376 nm) to be quenched. However, fluorescence is restored on addition of pyrene due to the strong affinity between Mb and aptamer which causes its separation from GO. Fluorescence increases linearly in the 5.6-450 pM Mb concentration range, and the lower detection limit is 3.9 pM (S/N = 3). The assay was applied to the determination of cardiac Mb in spiked serum, and satisfactory results were obtained. Graphical abstract Schematic presentation of the detection of Mb (cardiac myoglobin) by using a fluorometric method based on pyrene-modified anti-Mb aptamer and GO (graphene oxide) through fluorescence quenching and subsequent recovery.