Recent advances in electrochemical aptasensors and genosensors for the detection of pathogens.

In recent years, pathogenic microorganisms have caused significant mortality rates and antibiotic resistance and triggered exorbitant healthcare costs. These pathogens often have high transmission rates within human populations. Rapid diagnosis is crucial in controlling and reducing the spread of pathogenic infections. The diagnostic methods currently used against individuals infected with these pathogens include relying on outward symptoms, immunological-based and, some biomolecular ones, which mainly have limitations such as diagnostic errors, time-consuming processes, and high-cost platforms. Electrochemical aptasensors and genosensors have emerged as promising diagnostic tools for rapid, accurate, and cost-effective pathogen detection. These bio-electrochemical platforms have been optimized for diagnostic purposes by incorporating advanced materials (mainly nanomaterials), biomolecular technologies, and innovative designs. This review classifies electrochemical aptasensors and genosensors developed between 2021 and 2023 based on their use of different nanomaterials, such as gold-based, carbon-based, and others that employed other innovative assemblies without the use of nanomaterials. Inspecting the diagnostic features of various sensing platforms against pathogenic analytes can identify research gaps and open new avenues for exploration.

Cas14a1-advanced LAMP for ultrasensitive and visual Pathogen diagnostic.

Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas enzymes have been widely applied for biosensor development, combined with various isothermal amplification strategies (IAS) to boost sensitivity and specificity. Currently, the unstable assay and tedious manipulation usually hinder its practical applications. Here, a Cas14a1-advanced LAMP assay (CALA) combined with Rapid Extraction of Bacterial Genomic DNA (REBGD) is proposed for pathogen detection. For rapid CALA, a single stranded fluorescence reporter and ssDNA-gold nanoparticles (AuNPs) are used as signal indicators to establish ultrasensitive and visual platforms. This assay displays precise detection of bacteria, which can achieve an ultrasensitive limit of detection (LOD) 10 aM target genomic DNA. Furthermore, the high reliability of pathogen diagnostic for contrived samples is validated through the rapid visual CALA platform, demonstrating the promising practical testing availability of pathogen detection.

Design of an electrochemical aptasensor in the presence of an array of gold nanostructure and a GO-MWCNTs nanocomposite: application in diagnosis of Alzheimer's disease.

Alzheimer's disease (AD) is considered one of the main progressive chronic diseases in elderly individuals. Early diagnosis using related biomarkers, specifically beta-amyloid peptide (Aß), allows finding expected treatment routes. Here, we developed an electrochemical aptasensing platform for AD by employing a glassy carbon electrode (GCE) modified with a layer of jagged gold (JG) nanostructure (diameter: 60-185 nm) and graphene oxide-carboxylic acid functionalized multiwalled carbon nanotubes (GO-c-MWCNTs) nanocomposite. These surface modifications acted as the signal amplifier and provided an optimum nano-interface substrate for immobilizing aptamer strands. The measurements of Aß were performed via differential pulse voltammetry (DPV), and the aptasensor detected the analyte in a linear range from 0.1 pg mL-1 to 1 ng mL-1, with an estimated limit of detection (LOD) of about 0.088 pg mL-1 (S/N = 3). The aptasensor showed sufficient stability (11 days), reversibility (three times), and reproducibility (five times re-fabrication with relative standard deviation (RSD): 1.27). The potential interfering agents showed negligible impact on the sensing performance. Finally, the application of the aptasensor was evaluated in the presence of 10 serum samples, and the recovery values were from 93 to 110.1%.

Electrochemical Immunosensors Developed for Amyloid-Beta and Tau Proteins, Leading Biomarkers of Alzheimer's Disease.

Alzheimer's disease (AD) is the most common neurological disease and a serious cause of dementia, which constitutes a threat to human health. The clinical evidence has found that extracellular amyloid-beta peptides (Aß), phosphorylated tau (p-tau), and intracellular tau proteins, which are derived from the amyloid precursor protein (APP), are the leading biomarkers for accurate and early diagnosis of AD due to their central role in disease pathology, their correlation with disease progression, their diagnostic value, and their implications for therapeutic interventions. Their detection and monitoring contribute significantly to understanding AD and advancing clinical care. Available diagnostic techniques, including magnetic resonance imaging (MRI) and positron emission tomography (PET), are mainly used to validate AD diagnosis. However, these methods are expensive, yield results that are difficult to interpret, and have common side effects such as headaches, nausea, and vomiting. Therefore, researchers have focused on developing cost-effective, portable, and point-of-care alternative diagnostic devices to detect specific biomarkers in cerebrospinal fluid (CSF) and other biofluids. In this review, we summarized the recent progress in developing electrochemical immunosensors for detecting AD biomarkers (Aß and p-tau protein) and their subtypes (AßO, Aß(1-40), Aß(1-42), t-tau, cleaved-tau (c-tau), p-tau181, p-tau231, p-tau381, and p-tau441). We also evaluated the key characteristics and electrochemical performance of developed immunosensing platforms, including signal interfaces, nanomaterials or other signal amplifiers, biofunctionalization methods, and even primary electrochemical sensing performances (i.e., sensitivity, linear detection range, the limit of detection (LOD), and clinical application).

Paper-based electrochemical biosensors for the diagnosis of viral diseases.

Paper-based electrochemical analytical devices (ePADs) have gained significant interest as promising analytical units in recent years because they can be fabricated in simple ways, are low-cost, portable, and disposable platforms that can be applied in various fields. In this sense, paper-based electrochemical biosensors are attractive analytical devices since they can promote diagnose several diseases and potentially allow decentralized analysis. Electrochemical biosensors are versatile, as the measured signal can be improved by using mainly molecular technologies and nanomaterials to attach biomolecules, resulting in an increase in their sensitivity and selectivity. Additionally, they can be implemented in microfluidic devices that drive and control the flow without external pumping and store reagents, and improve the mass transport of analytes, increasing sensor sensitivity. In this review, we focus on the recent developments in electrochemical paper-based devices for viruses' detection, including COVID-19, Dengue, Zika, Hepatitis, Ebola, AIDS, and Influenza, among others, which have caused impacts on people's health, especially in places with scarce resources. Also, we discuss the advantages and disadvantages of the main electrode's fabrication methods, device designs, and biomolecule immobilization strategies. Finally, the perspectives and challenges that need to be overcome to further advance paper-based electrochemical biosensors' applications are critically presented.

Hybridization chain reaction cascaded amplification platform for sensitive detection of pathogen.

Rapid, sensitive, and accurate identification of pathogens is vital for preventing and controlling fish disease, reducing economic losses in aquaculture, and interrupting the spread of food-borne diseases in human populations. Herein, we proposed a hybridization chain reaction (HCR) cascaded dual-signal amplification platform for the ultrasensitive and specific detection of pathogenic microorganisms. A couple of specific primers for target bacterial 16S rRNAs were used to obtain amplified target single-stranded DNAs (AT-ssDNA). Then, AT-ssDNA initiated HCR amplification along with the opening of fluorophore (FAM) and a quencher (BHQ1) labeled hairpin reporter probe (H1), and the FAM fluorescence signal recovered. The proposed strategy could achieve a detection limit down to 0.31 CFU/mL for Staphylococcus aureus (S. aureus), 0.49 CFU/mL for Escherichia coli (E. coli) in buffer, and a linear range from 1 to 1 × 106 CFU/mL for S. aureus, 1 to 1 × 107 CFU/mL for E. coli. Furthermore, this platform enabled sensitive and precise detection of pathogenic microorganisms in complex samples such as fish blood and different organ tissues (large intestine, gallbladder, heart, liver, ren, gill, skin), which shows great potential in disease prevention and control in aquatic products.

High-throughput and specific detection of microorganisms by intelligent modular fluorescent photoelectric microbe detector.

Food safety has emerged as a major global issue. Detecting foodborne pathogenic microorganisms and controlling them is vital to guard against foodborne diseases caused by microorganisms. However, the current detection methods need to meet the demand for real-time detection on the spot after a simple operation. Considering unresolved challenges, we developed an Intelligent Modular Fluorescent Photoelectric Microbe (IMFP) system containing a special detection reagent. This IMFP system can automatically monitor microbial growth in which the photoelectric detection, temperature control, fluorescent probe, and bioinformatics screen are integrated into one platform and employed to detect pathogenic microorganisms. Moreover, a specific culture medium was also developed, which matched the system platform for Coliform bacteria and Salmonella typhi. The developed IMFP system could attain a limit of detection (LOD) of about 1 CFU/mL for both bacteria, while the selectivity could reach 99%. In addition, the IMFP system was applied to detect 256 bacterial samples simultaneously. This platform reflects the high-throughput needs of fields for microbial identification and related requirements, such as the development of pathogenic microbial diagnostic reagents, antibacterial sterilization performance tests, and microbial growth kinetics. The IMFP system also confirmed the other merits, such as high sensitivity, high-throughput, and operation simplicity compared to conventional methods, and it has a high potential as a tool for application in the health and food security fields.

Recent advances in electrochemical nanomaterial-based aptasensors for the detection of cancer biomarkers.

New technologies have provided suitable tools for rapid diagnosis of cancer which can reduce treatment costs and even increase patients' survival rates. Recently, the development of electrochemical aptamer-based nanobiosensors has raised great hopes for early, sensitive, selective, and low-cost cancer diagnosis. Here, we reviewed the flagged recent research (2021-2023) developed as a series of biosensors equipped with nanomaterials and aptamer sequences (nanoaptasensors) to diagnose/prognosis of various types of cancers. Equipping these aptasensors with nanomaterials and using advanced biomolecular technologies have provided specified biosensing interfaces for more optimal and reliable detection of cancer biomarkers. The primary intention of this review was to present and categorize the latest innovations used in the design of these diagnostic tools, including the hottest surface modifications and assembly of sensing bioplatforms considering diagnostic mechanisms. The main classification is based on applying various nanomaterials and sub-classifications considered based on the type of analyte and other vital features. This review may help design subsequent electrochemical aptasensors. Likewise, the up-to-date status, remaining limitations, and possible paths for translating aptasensors to clinical cancer assay tools can be clarified.

Sandwich-like electrochemical aptasensing of heat shock protein 70 kDa (HSP70): Application in diagnosis/prognosis of coronavirus disease 2019 (COVID-19).

In this research, by using aptamer-conjugated gold nanoparticles (aptamer-AuNPs) and a modified glassy carbon electrode (GCE) with reduced graphene oxide (rGO) and Acropora-like gold (ALG) nanostructure, a sandwich-like system provided for sensitive detection of heat shock protein 70 kDa (HSP70), which applied as a functional biomarker in diagnosis/prognosis of COVID-19. Initially, the surface of the GCE was improved with rGO and ALG nanostructures, respectively. Then, an aptamer sequence as the first part of the bioreceptor was covalently bound on the surface of the GCE/rGO/ALG nanostructures. After adding the analyte, the second part of the bioreceptor (aptamer-AuNPs) was immobilized on the electrode surface to improve the diagnostic performance. The designed aptasensor detected HSP70 in a wide linear range, from 5 pg mL-1 to 75 ng mL-1, with a limit of detection (LOD) of ∼2 pg mL-1. The aptasensor was stable for 3 weeks and applicable in detecting 40 real plasma samples of COVID-19 patients. The diagnostic sensitivity and specificity were 90% and 85%, respectively, compared with the reverse transcription-polymerase chain reaction (RT-PCR) method.

Electrochemical Nanomaterial-based Sensors/Biosensors for Drug Monitoring.

Determining the amount of medication used is essential for correctly managing treatment systems. The unauthorized use of drugs and the importance of determining the absorbed and required dose of drugs in target organs are essential factors that justify the design of new drug monitoring systems. Electrochemical sensors and biosensors based on nanomaterials have been developed for drug monitoring in the past few years. The use of nanomaterials to optimize the analyte detection process and facilitate electron transfer in electrochemical processes has enhanced intermolecular interactions and increased diagnostic sensitivity. Considering this review, in the first part, the evaluation of cancer drugs is examined, which can be used to determine the exact dose of the drug required in different stages of cancer. Accurate monitoring of cancer drugs can increase patient life expectancy, reduce side effects, and increase economic savings. In the next section, sensors and biosensors designed for antibiotics are examined. Accurate measurement of antibiotics for determining the effectiveness of the dose in controlling infections and preventing antibiotic resistance is possible with the help of these drug diagnostic platforms. In the next part, the diagnosis of different hormones is considered. Abnormal amounts (low/high) of hormones cause multiple physiological complications and various disabilities. Therefore, accurate determination of hormone levels can effectively treat hormonal changes. In the last section, other drugs, including drugs and analgesics for which the use of electrochemical diagnostic platforms can significantly help drug distribution and social health systems, are also discussed.

Electrochemical aptamer-based nanobiosensors for diagnosing Alzheimer's disease: A review.

Diagnosis and prognosis of Alzheimer's disease by electrochemical nanoaptasensors have recently received abundant attention. In this review, all recent nanomaterial-based electrochemical aptasensors developed to diagnose or prognosis Alzheimer's disease have been collected, categorized, and reviewed. Analytes in these aptasensors were specific biomarkers, including amyloid-ß (Aß) and tau protein, as well as other nonspecific markers (microRNAs (miRNAs), dopamine, thrombin, adenosine triphosphate (ATP), interleukin-6, α-1 antitrypsin, α-synuclein, target DNA (tDNA), and glycated albumin). The synthesis methods of the applied nanomaterials, characterization, and applications have also been considered here. Gold nanostructures were the most nanomaterials applied in the structure of considered aptasensors. The use of the most optimal nanomaterials in the structure of these diagnostic tools has been dependent on various parameters, the most important of which are the type of signal transducer and the functional group related to the biorecognition element. In general, the choice of nanomaterials in these biosensors depends on interactions between nanomaterials and other molecules or environments. Indeed, with the assistance of nanomaterials, more expansive active surfaces have been created in the interactions of aptasensors components that have played a very positive and efficient role in amplifying the output signals and increasing the analytical/diagnostic sensitivity. The diagnostic mechanisms and the interaction between the various components of aptasensors and the nanomaterials' position were also considered. The main achievements were classification, analysis, and scheming of the elements and techniques used, the possibility of comparing detection range, and the limit of detection (LOD).

An aptasensing platform for detection of heat shock protein 70 kDa (HSP70) using a modified gold electrode with lady fern-like gold (LFG) nanostructure.

Early diagnosis of diseases depends on accessibility and the ability to detect associated biomarkers. Using aptamers and equipping signal transducers with nanomaterials have facilitated, accelerated, and provided sensitive and selective nanoaptasensors. In this study, the first aptasensor to detect heat shock protein 70 kDa (HSP70) has been developed by applying a modified gold electrode (GE) with the lady fern-like gold (LFG) nanostructure. The nanostructure solution contained HAuCl4, H2SO4, and histamine and was electrochemically synthesized on the surface of the GE with an average size of ∼20 nm. The analysis to find the optimized time for immobilization of aptamer (a single-stranded RNA) as the biorecognition element on the surface of the working electrode was performed using the open-circuit potential (OCP) technique. This aptasensor could detect HSP70 in a linear range from 0.05 to 75 ng mL-1 with the limit of detection (LOD) âˆ¼ 0.02 ng mL-1. In order to find out about the performance of the designed aptasensor, other analytical analyses for knowing about the figure of metrics were shadowed through reproducibility, stability, regeneration, selectivity, accuracy, and precision experiments.

Electrochemical nanobiosensors equipped with peptides: a review.

Recent research in the field of electrochemical biosensors equipped with peptides and nanomaterials have been categorized, reviewed, and critically analyzed. Indeed, using these innovative biosensors can revolutionize biomedical diagnostics in the future. Saving lives, time, and money in this field will be considered as some main benefits of this type of diagnosis. Here, these biosensors have been categorized and evaluated in four main sections. In the first section, the focus is on investigating the types of electrochemical peptide-based nanobiosensors applied to detect pathogenic microorganisms, microbial toxins, and viruses. In the second section, due to the importance of rapid diagnosis and prognosis of various cancers, the electrochemical peptide-based nanobiosensors designed to detect cancer biomarkers have been reviewed and analyzed. In the third section, the electrochemical peptide-based nanobiosensors, which were applied to detect the essential and effective biomolecules in the various diseases, and health control, including enzymes, hormones, biomarkers, and other biomolecules, have been considered. Finally, using a comprehensive analysis, all the used elements in these biosensors have been presented as conceptual diagrams that can effectively guide researchers in future developments. The essential factors in evaluating and analyzing these electrochemical peptide-based nanobiosensors such as analyte, peptide sequence, functional groups interacted between the peptide sequences and other biosensing components, the applied nanomaterials, diagnostic techniques, detection range, and limit of detection have also been included. Other analyzable items such as the type of used redox marker and the location of the peptide sequence against the signal transducer were also considered.

Electrochemical aptasensors based on the gold nanostructures.

Electrochemical aptasensors as novel diagnostic tools have attracted sufficient research interest in biomedical sciences. In this review, recent leading trends about gold (Au) nanostructures based electrochemical aptasensors have been collected, reviewed, and compared. Here, the considered electrochemical aptasensors were categorized based on the analytes and diagnostic techniques. Pharmaceutical analytes and biomolecules were reviewed in a separate section consisting of a variety of antibiotics, analgesics, and other biomolecules. Various aptasensors have also measured toxins, ions, and hazardous chemicals, and the findings of them have also been reviewed. Many aptasensors have been designed to detect different disease biomarkers that will play an essential role in the future of early diagnosis of diseases. Pathogen microorganisms have been considered as the analyte in several designed electrochemical aptasensors in recent researches, and their results have been reviewed and discussed as another section. Important aspects considered in the review of the mentioned aptasensors were the type of analyte, features of the aptamer as the biorecognition element, type of Au nanostructures, diagnostic technique, diagnostic mechanism, detection range and the limit of detection (LOD). In the last section, an in-depth analysis has been provided based on the crucial features of all included aptasensors.

Antibacterial Assessment of Zinc Sulfide Nanoparticles against Streptococcus pyogenes and Acinetobacter baumannii.

BACKGROUND: Due to the appearance of resistant bacterial strains against the antimicrobial drugs and the reduced efficiency of these valuable resources, the health of a community and the economies of countries have been threatened. OBJECTIVE: In this study, the antibacterial assessment of zinc sulfide nanoparticles (ZnS NPs) against Streptococcus pyogenes and Acinetobacter baumannii has been performed. METHODS: ZnS NPs were synthesized through a co-precipitation method using polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA) and polyethylene glycol (PEG-4000). The size and morphology of the synthesized ZnS NPs were determined by a scanning electron microscope (SEM) and it was found that the average size of the applied NPs was about 70 nm. In order to evaluate the antibacterial effect of the synthesized ZnS NPs, various concentrations (50µg/mL, 100 µg/mL and 150 µg/mL) of ZnS NPs were prepared. Antibacterial assessments were performed through the disc diffusion method in Mueller Hinton Agar (MHA) culture medium and also the optical density (OD) method was performed by a UV-Vis spectrophotometer in Trypticase™ Soy Broth (TSB) medium. Then, in order to compare the antibacterial effects of the applied NPs, several commercial antibiotics including penicillin, amikacin, ceftazidime and primaxin were used. RESULTS: The achieved results indicated that the antibacterial effects of ZnS NPs had a direct relation along with the concentrations and the concentration of 150 µg/mL showed the highest antibacterial effect in comparison with others. In addition, the ZnS NPs were more effective on Acinetobacter baumannii. CONCLUSION: The findings of this research suggest a novel approach against antibiotic resistance.

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.

An electrochemical peptide-based biosensor for the Alzheimer biomarker amyloid-ß(1-42) using a microporous gold nanostructure.

Alzheimer's disease (AD) is connected to aggregation of amyloid-ß (Aß) peptide and formation of insoluble plaques in the brain. Aß level can be monitored as an AD early diagnosis route. In this study, an irregular shaped microporous gold nanostructure with a typical size of 150 × 250 nm was electrodeposited on a polycrystalline gold surface at 0 mV (vs. AgCl) using sodium alendronate. The nanostructure was then characterized by field-emission scanning electron microscopy. An electrochemical peptide-based biosensor was fabricated by immobilizing an Aß(1-42)-binding peptide on the gold nanostructure. Binding of Aß(1-42) by the peptide was followed electrochemically using ferro/ferricyanide as a redox probe. Differential pulse voltammograms in a potential range of 0-500 mV (vs. AgCl) with typical peak potentials at 224 mV are linear in the 3-7000 pg mL-1 Aß(1-42) concentration range, with a 0.2 pg mL-1 detection limit. The biosensor is free of interferences and was applied to the quantitation of Aß(1-42) in artificial cerebrospinal fluid and spiked serum samples. Graphical abstractSchematic presentation of an immobilized amyloid-ß(1-42)-specific peptide on the surface of a microporous gold nanostructure to fabricate an electrochemical biosensor for early diagnosis of Alzheimer's disease. Aß(1-42) capturing by the peptide led to repulsion of ferrocyanide/ferricyanide redox couple.

An electrochemical troponin T aptasensor based on the use of a macroporous gold nanostructure.

A specific troponin T (TnT) binding aptamer was identified and immobilized on an electrodeposited macroporous gold nanostructure using poly(ethylene glycol) 600, to fabricate a novel and ultrasensitive TnT aptasensor. The transducer surface on the gold disk electrode was characterized by field emission scanning electron microscopy, and immobilization of the aptamer was monitored by open circuit potential measurements. Binding of TnT by the aptamer was monitored by differential pulse voltammetry using ferro/ferricyanide as the redox probe. The aptamer has a high affinity and specificity, and the electrode is sensitive and selective. Best operated at a working potential of 0.23 V (vs. Ag/AgCl), the electrode can detected TnT in the 0.05 to 5.0 ng mL-1 concentration range with a 23 pg mL-1 detection limit. The method was applied to the determination of TnT in 99 spiked human serum samples, and the diagnostic sensitivity and specificity were 94 and 95%, respectively. Graphical abstract Schematic presentation of an electrochemical troponin T aptasensor. A macroporous gold nanostructure was electrodeposited followed by immobilization of a specific TnT aptamer. Binding of TnT by the aptamer was electrochemically monitored. MCH: mercaptohexanol; TnT: troponin T.