Electrochemical biosensors for hormone analyses

A label-free colorimetric biosensor utilizing natural material for highly sensitive exosome detection

Exosomes, extracellular vesicles secreted by cells, play a crucial role in intercellular communication by transferring information from source cells to recipient cells. These vesicles carry important biomarkers, including nucleic acids and proteins, which provide valuable insights into the parent cells' status. As a result, exosomes have emerged as noninvasive indicators for the early diagnosis of cancer. Colorimetric biosensors have garnered significant attention due to their cost-effectiveness, simplicity, rapid response, and reproducibility. In this study, we employ sporopollenin microcapsules (SP), a natural biopolymer material derived from pollen, as a substrate for gold nanoparticles (AuNPs). By modifying the SP-Au complex with CD63 aptamers, we develop a label-free colorimetric biosensor for exosome detection. In the absence of exosomes, the SP-Au complex catalyzes the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB), resulting in a color change from colorless to blue. However, the addition of exosomes inhibits the catalytic activity of the SP-Au complex due to coverage of exosomes on AuNPs. This colorimetric biosensor exhibits high sensitivity and selectivity for exosome detection, with a detection limit of 10 particles/μL and a wide linear range of 10 - 108 particles/μL. Additionally, the SP-Au biosensor demonstrates remarkable resistance to serum protein adsorption and excellent catalytic stability even in harsh environments, making it highly suitable for clinical diagnostics.

A new insight into the early detection of HER2 protein in breast cancer patients with a focus on electrochemical biosensors approaches: A review

Breast cancer is one of the leading causes of death in women and is a prevalent kind of cancerous growth, representing a substantial risk to women's health. Early detection of breast cancer is essential for effective treatment and improved survival rates. Biomarkers, active substances that signal the existence and advancement of a tumor, play a significant role in the early detection of breast cancer. Hence, accurate identification of biomarkers for tumors is crucial for diagnosing and treating breast cancer. However, the primary diagnostic methods used for the detection of breast cancer require specific equipment, skilled professionals, and specialized analysis, leading to elevated detection expenses. Regarding this obstacle, recent studies emphasize electrochemical biosensors as more advanced and sensitive detection tools compared to traditional methods. Electrochemical biosensors are employed to identify biomarkers that act as unique indicators for the onset, recurrence, and monitoring of therapeutic interventions for breast cancer. This study aims to provide a summary of the electrochemical biosensors that have been employed for the detection of breast cancer at an early stage over the past decade. Initially, the text provides concise information about breast cancer and tumor biomarkers. Subsequently, an in-depth analysis is conducted to systematically review the progress of electrochemical biosensors developed for the stable, specific, and sensitive identification of biomarkers associated with breast cancer. Particular emphasis was given to crucial clinical biomarkers, specifically the human epidermal growth factor receptor-2 (HER2). The analysis then explores the limitations and challenges inherent in the design of effective biosensors for diagnosing and treating breast cancer. Ultimately, we provided an overview of future research directions and concluded by outlining the advantages of electrochemical biosensor approaches.

An Innovative SbIII-WVI-Cotemplated Antimonotungstate with Potential in Sensing Paroxetine Electrochemically

Advances in polyoxometalate (POM) self-assembly chemistry are always accompanied by new developments in molecular blocks. The exploration and discovery of uncommon building blocks offer great possibilities for generating unprecedented POM clusters. An intriguing SbIII-WVI-cotemplated antimonotungstate [H2N(CH3)2]11Na[SbW9O33]Er2(H2O)2Sb2[SbWVIW15O57]·22H2O (1) was synthesized, which comprises a classical trivacant Keggin [SbW9O33]9- ({SbW9}) fragment and an unclassical lacunary Dawson-like [SbWVIW15O57]15- ({SbWVIW15}) subunit. Notably, the Dawson-like {SbWVIW15} subunit is the first example of a [SbO3]3- and [WVIO6]6- mixed-heteroatom-directing POM segment. Hexacoordinated [WVIO6]6- can not only serve as the heteroatom function but its additional oxygen sites can also link to lanthanide, main-group metal, and transition-metal centers to form the innovative structure. {SbWVIW15} and {SbW9} subunits are joined by the heterometallic [Er2(H2O)2Sb2O17]22- cluster to give rise to an asymmetric sandwich-type architecture. To further realize its potential application in electrochemical sensing, a conductive 1@rGO composite was obtained by the electrochemical deposition of 1 with graphene oxide (GO). Using a 1@rGO-modified glassy carbon electrode as the working electrode, an electrochemical biosensor for detecting the antidepressant drug paroxetine (PRX) was successfully constructed. This work can provide a viable strategy for synthesizing mixed-heteroatom-directing POMs and demonstrates the application of POM-based materials for the electrochemical detection of drug molecules.

ACEK Biosensor for the Minute-Scale Quantification of Breast Cancer ctDNA

Circulating tumor DNA (ctDNA) appears as a valuable liquid biopsy biomarker in the early diagnosis, treatment, and prognosis of cancer. Here, a biosensing method derived from the AC electrokinetics (ACEK) effect was constructed in this study for the simple, efficient, and rapid method of detection of ctDNA. In the proof-of-concept experiment, ctDNA from the PIK3CA E542K mutant in breast cancer was quantified by detecting a normalized capacitance change rate using a forked-finger gold electrode as the sensing electrode in combination with the ACEK effect. We compared two formats for the construction of the approach by employing varied immobilization strategies; one is to immobilize the DNA capture probe on the electrode surface by Au-S bonding, while the other immobilizes the probe on a self-assembled membrane on the electrode surface by amide bonding. Both formats demonstrated ultrafast detection speed by completing the ctDNA quantification within 1 min and a linear range of 10 fM-10 pM was observed. Meanwhile, the immobilization via the self-assembled membrane yielded improved stability, sensitivity, and specificity than its Au-S bonding counterpart. A detection limit of 1.94 fM was eventually achieved using the optimized approach. This research provides a label-free and minute-scale universal method for the detection of various malignant tumors. The ctDNA biosensors based on the ACEK effect improved according to the probe type or electrode structure and have potential applications in tumor drug efficacy prediction, drug resistance monitoring, screening of high-risk groups, differential diagnosis, monitoring of tiny residual lesions, and prognosis determination.

Not Only Graphene Two-Dimensional Nanomaterials: Recent Trends in Electrochemical (Bio)sensing Area for Biomedical and Healthcare Applications

Two-dimensional (2D) nanomaterials (e.g., graphene) have attracted growing attention in the (bio)sensing area and, in particular, for biomedical applications because of their unique mechanical and physicochemical properties, such as their high thermal and electrical conductivity, biocompatibility, and large surface area. Graphene (G) and its derivatives represent the most common 2D nanomaterials applied to electrochemical (bio)sensors for healthcare applications. This review will pay particular attention to other 2D nanomaterials, such as transition metal dichalcogenides (TMDs), metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and MXenes, applied to the electrochemical biomedical (bio)sensing area, considering the literature of the last five years (2018-2022). An overview of 2D nanostructures focusing on the synthetic approach, the integration with electrodic materials, including other nanomaterials, and with different biorecognition elements such as antibodies, nucleic acids, enzymes, and aptamers, will be provided. Next, significant examples of applications in the clinical field will be reported and discussed together with the role of nanomaterials, the type of (bio)sensor, and the adopted electrochemical technique. Finally, challenges related to future developments of these nanomaterials to design portable sensing systems will be shortly discussed.

Tip-Enhanced Sub-Femtomolar Steroid Immunosensing via Micropyramidal Flexible Conducting Polymer Electrodes for At-Home Monitoring of Salivary Sex Hormones

Noninvasive testing and continuous monitoring of ultralow-concentration hormones in biofluids have attracted increasing interest for health management and personalized medicine, in which saliva could fulfill the demand. Steroid sex hormones such as progesterone (P4) and β-estradiol (E2) are crucial for female wellness and reproduction; however, their concentrations in saliva can vary down to sub-pM and constantly fluctuate over several orders of magnitude. This remains a major obstacle toward user-friendly and reliable monitoring at home with low-cost flexible biosensors. Herein we introduce a 3D micropyramidal electrode architecture to address such challenges and achieve an ultrasensitive flexible electrochemical immunosensor with sub-fM-level detection capability of salivary sex hormones within a few minutes. This is enabled by micropyramidal electrode arrays consisting of a poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) thin film as the coating layer and electrochemically decorated gold nanoparticles (AuNPs) to improve the antibody immobilization. The enhanced mass transport around the 3D tips provided by the micropyramidal architecture is discovered to improve the detection limit by 3 orders of magnitude, pushing it to as low as ∼100 aM for P4 and ∼20 aM for E2, along with a wide linear range up to μM. Accordingly, these hormones down to sub-fM in >1000-fold-diluted saliva samples can be accurately measured by the printed soft immunosensors, thus allowing at-home testing through simple saliva dilution to minimize the interfering substances instead of centrifugation. Finally, monitoring of the female ovarian hormone cycle of both P4 and E2 is successfully demonstrated based on the centrifuge-free saliva testing during a period of 4 weeks. This ultrasensitive and soft 3D microarchitected electrode design is believed to provide a universal platform for a diverse variety of applications spanning from accurate clinical diagnostics and counselling and in vivo detection of bioactive species to environmental and food quality tracing.

Iron/iron oxide-based magneto-electrochemical sensors/biosensors for ensuring food safety: recent progress and challenges in environmental protection

Foodborne diseases have arisen due to the globalization of industry and the increase in urban population, which has led to increased demand for food and has ultimately endangered the quality of food. Foodborne diseases have caused some of the most common public health problems and led to significant social and economic issues worldwide. Food quality and safety are affected by microbial contaminants, growth-promoting feed additives (β-agonists and antibiotics), food allergens, and toxins in different stages from harvesting to storage and marketing of products. Electrochemical biosensors, due to their reduced size and portability, low cost, and low consumption of reagents and samples, can quickly provide valuable quantitative and qualitative information about food contamination. In this regard, using nanomaterials can increase the sensitivity of the assessment. Magnetic nanoparticle (MNP)-based biosensors, especially, are receiving significant attention due to their low-cost production, physicochemical stability, biocompatibility, and eco-friendly catalytic characteristics, along with magnetic, biological, chemical and electronic sensing features. Here, we provide a review on the application of iron-based magnetic nanoparticles in the electrochemical sensing of food contamination. The types of nanomaterials used in order to improve the methods and increase the sensitivity of the methods have been discussed. Then, we stated the advantages and limitations of each method and tried to state the research gaps for each platform/method. Finally, the role of microfluidic and smartphone-based methods in the rapid detection of food contamination is stated. Then, various techniques like label-free and labelled regimes for the sensitive monitoring of food contamination were surveyed. Next, the critical role of antibody, aptamer, peptide, enzyme, DNA, cells and so on for the construction of specific bioreceptors for individual and simultaneous recognition by electrochemical methods for food contamination were discussed. Finally, integration of novel technologies such as microfluidic and smartphones for the identification of food contaminations were investigated. It is important to point out that, in the last part of each sub-section, attained results of different reports for each strategy were compared and advantages/limitations were mentioned.

Electrochemical biosensors for monitoring of selected pregnancy hormones during the first trimester: A systematic review

The hormones human chorionic gonadotropin, progesterone, estrogen and four of its metabolites (estradiol, estrone, estriol, estetrol), as well as relaxin play an essential role in the development of the fetus during the first trimester. Imbalances in these hormones during the first trimester have been directly linked to miscarriages. However, frequent monitoring of the hormones is limited by the current conventional centralized analytical tools that do not allow a rapid response time. Electrochemical sensing is considered an ideal tool to detect hormones owing to its advantages such as quick response, user-friendliness, low economic costs, and possibility of use in point-of-care settings. Electrochemical detection of pregnancy hormones is an emerging field that has been demonstrated primarily at research level. Thus, it is timely with a comprehensive overview of the characteristics of the reported detection techniques. This is the first extensive review focusing on the advances related to electrochemical detection of hormones linked to the first trimester of pregnancy. Additionally, this review offers insights into the main challenges that must be addressed imminently to ensure progress from research to clinical applications.

Advances on Hormones in Cosmetics: Illegal Addition Status, Sample Preparation, and Detection Technology

Owing to the rapid development of the cosmetic industry, cosmetic safety has become the focus of consumers' attention. However, in order to achieve the desired effects in the short term, the illegal addition of hormones in cosmetics has emerged frequently, which could induce skin problems and even skin cancer after long-term use. Therefore, it is of great significance to master the illegal addition in cosmetics and effectively detect the hormones that may exist in cosmetics. In this review, we analyze the illegally added hormone types, detection values, and cosmetic types, as well as discuss the hormone risks in cosmetics for human beings, according to the data in unqualified cosmetics in China from 2017 to 2022. Results showed that although the frequency of adding hormones in cosmetics has declined, hormones are still the main prohibited substances in illegal cosmetics, especially facial masks. Because of the complex composition and the low concentration of hormones in cosmetics, it is necessary to combine efficient sample preparation technology with instrumental analysis. In order to give the readers a comprehensive overview of hormone analytical technologies in cosmetics, we summarize the advanced sample preparation techniques and commonly used detection techniques of hormones in cosmetics in the last decade (2012-2022). We found that ultrasound-assisted extraction, solid phase extraction, and microextraction coupled with chromatographic analysis are still the most widely used analytical technologies for hormones in cosmetics. Through the investigation of market status, the summary of sample pretreatment and detection technologies, as well as the discussion of their development trends in the future, our purpose is to provide a reference for the supervision of illegal hormone residues in cosmetics.

Recent Developments in Electrochemical-Impedimetric Biosensors for Virus Detection

Viruses, including influenza viruses, MERS-CoV (Middle East respiratory syndrome coronavirus), SARS-CoV (severe acute respiratory syndrome coronavirus), HAV (Hepatitis A virus), HBV (Hepatitis B virus), HCV (Hepatitis C virus), HIV (human immunodeficiency virus), EBOV (Ebola virus), ZIKV (Zika virus), and most recently SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), are responsible for many diseases that result in hundreds of thousands of deaths yearly. The ongoing outbreak of the COVID-19 disease has raised a global concern and intensified research on the detection of viruses and virus-related diseases. Novel methods for the sensitive, rapid, and on-site detection of pathogens, such as the recent SARS-CoV-2, are critical for diagnosing and treating infectious diseases before they spread and affect human health worldwide. In this sense, electrochemical impedimetric biosensors could be applied for virus detection on a large scale. This review focuses on the recent developments in electrochemical-impedimetric biosensors for the detection of viruses.

Hydrogel-Based Biosensors

There is an increasing interest in sensing applications for a variety of analytes in aqueous environments, as conventional methods do not work reliably under humid conditions or they require complex equipment with experienced operators. Hydrogel sensors are easy to fabricate, are incredibly sensitive, and have broad dynamic ranges. Experiments on their robustness, reliability, and reusability have indicated the possible long-term applications of these systems in a variety of fields, including disease diagnosis, detection of pharmaceuticals, and in environmental testing. It is possible to produce hydrogels, which, upon sensing a specific analyte, can adsorb it onto their 3D-structure and can therefore be used to remove them from a given environment. High specificity can be obtained by using molecularly imprinted polymers. Typical detection principles involve optical methods including fluorescence and chemiluminescence, and volume changes in colloidal photonic crystals, as well as electrochemical methods. Here, we explore the current research utilizing hydrogel-based sensors in three main areas: (1) biomedical applications, (2) for detecting and quantifying pharmaceuticals of interest, and (3) detecting and quantifying environmental contaminants in aqueous environments.

Enhanced susceptibility of SARS-CoV-2 spike RBD protein assay targeted by cellular receptors ACE2 and CD147: Multivariate data analysis of multisine impedimetric response

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) enters the cells through the binding of spike protein to the host cell surface-expressing angiotensin-converting enzyme 2 (ACE2) or by endocytosis mediated by extracellular matrix metalloproteinase inducer (CD147). We present extended statistical studies of the multisine dynamic electrochemical impedance spectroscopy (DEIS) revealing interactions between Spike RBD and cellular receptors ACE2 and CD147, and a reference anti-RBD antibody (IgG2B) based on a functionalised boron-doped diamond (BDD) electrode. The DEIS was supported by a multivariate data analysis of a SARS-CoV-2 Spike RBD assay and cross-correlated with the atomic-level information revealed by molecular dynamics simulations. This approach allowed us to study and detect subtle changes in the electrical properties responsible for the susceptibility of cellular receptors to SARS-CoV-2, revealing their interactions. Changes in electrical homogeneity in the function of the RBD concentration led to the conclusion that the ACE2 receptor delivers the most homogeneous surface, delivered by the high electrostatic potential of the relevant docking regions. For higher RBD concentrations, the differences in electrical homogeneity between electrodes with different receptors vanish. Collectively, this study reveals interdependent virus entry pathways involving separately ACE2, CD147, and spike protein, as assessed using a biosensing platform for the rapid screening of cellular interactions (i.e. testing various mutations of SARS-CoV-2 or screening of therapeutic drugs).

Metal-organic frameworks as a therapeutic strategy for lung diseases

Lung diseases remain a global burden today. Lower respiratory tract infections alone cause more than 3 million deaths worldwide each year and are on the rise every year. In particular, with coronavirus disease raging worldwide since 2019, we urgently require a treatment for lung disease. Metal organic frameworks (MOFs) have a broad application prospect in the biomedical field due to their remarkable properties. The unique properties of MOFs allow them to be applied as delivery materials for different drugs; diversified structural design endows MOFs with diverse functions; and they can be designed as various MOF-drug synergistic systems. This review concentrates on the synthesis design and applications of MOF based drugs against lung diseases, and discusses the possibility of preparing MOF-based inhalable formulations. Finally, we discuss the chances and challenges of using MOFs for targeting lung diseases in clinical practice.

Impedance Analysis of Electrochemical Systems

Interpretation of impedance spectroscopy data requires both a description of the chemistry and physics that govern the system and an assessment of the error structure of the measurement. The approach presented here includes use of graphical methods to guide model development, use of a measurement model analysis to assess the presence of stochastic and bias errors, and a systematic development of interpretation models in terms of the proposed reaction mechanism and physical description. Application to corrosion, batteries, and biological systems is discussed, and emerging trends in interpretation and implementation of impedance spectroscopy are presented.

Green Synthesis of ZnO/BC Nanohybrid for Fast and Sensitive Detection of Bisphenol A in Water

A nanohybrid of zinc oxide and biochar (ZnO/BC) with high conductivity was green synthesized using a simple hydrothermal method, and utilized for the sensitive detection of bisphenol A (BPA) by coating the nanohybrid film on an electrode of glassy carbon. The ZnO/BC presented greatly improved electrocatalytic performance and electron transfer ability compared to the zinc oxide and biochar. The ZnO/BC film-coated electrode could detect the BPA in aqueous solution within 3 min while neglected interference from higher concentrations of regularly existing ions and similar concentrations of estradiol (E2), phenol, dichlorophenol (DCP), and ethinylestradiol (EE2). Under optimal conditions, the linear range of BPA detection was 5 × 10−7~1 × 10−4 mol/L, with a detection limit of 1 × 10−7 mol/L, and the detection sensitivity was 92 mA/M. In addition, the ZnO/BC electrode could detect BPA in a real water sample with good signal recovery. This electrode, with the advantages of an easy preparation, low cost, and fast response time, could be potentially applicable for environmental monitoring.

Recent advances in the potential applications of luminescence-based, SPR-based, and carbon-based biosensors

Abstract

The need for biosensors has evolved in the detection of molecules, diseases, and pollution from various sources. This requirement has headed to the development of accurate and powerful equipment for analysis using biological sensing component as a biosensor. Biosensors have the advantage of rapid detection that can beat the conventional methods for the detection of the same molecules. Bio-chemiluminescence-based sensors are very sensitive during use in biological immune assay systems. Optical biosensors are emerging with time as they have the advantage that they act with a change in the refractive index. Carbon nanotube-based sensors are another area that has an important role in the biosensor field. Bioluminescence gives much higher quantum yields than classical chemiluminescence. Electro-generated bioluminescence has the advantage of miniature size and can produce a high signal-to-noise ratio and the controlled emission. Recent advances in biological techniques and instrumentation involving fluorescence tag to nanomaterials have increased the sensitivity limit of biosensors. Integrated approaches provided a better perspective for developing specific and sensitive biosensors with high regenerative potentials. This paper mainly focuses on sensors that are important for the detection of multiple molecules related to clinical and environmental applications.

Key points

• The review focusses on the applications of luminescence-based, surface plasmon resonance-based, carbon nanotube-based, and graphene-based biosensors

• Potential clinical, environmental, agricultural, and food industry applications/uses of biosensors have been critically reviewed

• The current limitations in this field are discussed, as well as the prospects for future advancement

Smartphone-based mobile biosensors for the point-of-care testing of human metabolites

Rapid, accurate, portable and quantitative profiling of metabolic biomarkers is of great importance for disease diagnosis and prognosis. The recent development in the optical and electric biosensors based on the smartphone is promising for profiling of metabolites with advantages of rapid, reliability, accuracy, low-cost and multi-analytes analysis capability. In this review, we introduced the optical biosensing platforms including colorimetric, fluorescent and chemiluminescent sensing, and electrochemical biosensing platforms including wired and wireless communication. Challenges and future perspectives desired for reliable, accurate, cost-effective, and multi-functions smartphone-based biosensing systems were also discussed. We envision that such smartphone-based biosensing platforms will allow daily and comprehensive metabolites monitoring in the future, thus unlocking the potential to transform clinical diagnostics into non-clinical self-testing. We also believed that this progress report will encourage future research to develop advanced, integrated and multi-functional smartphone-based Point-of-Care testing (POCT) biosensors for the monitoring and diagnosis as well as personalized treatments of a spectrum of metabolic-disorder related diseases.

Translation of aptamers toward clinical diagnosis and commercialization

The dominance of antibodies in diagnostics has gradually changed following the discovery of aptamers in the early 1990s. Aptamers offer inherent advantages over traditional antibodies, including higher specificity, higher affinity, smaller size, greater stability, ease of manufacture, and low immunogenicity, rendering them the best candidates for point-of-care testing (POCT). In the past 20 years, the research community and pharmaceutical companies have made great efforts to promote the development of aptamer technology. Macugen® (pegaptanib) was the first aptamer drug approved by the US Food and Drug Administration (FDA), and various aptamer-based diagnostics show great promise in preclinical research and clinical trials. In this review, we introduce recent literature, ongoing clinical trials, commercial reagents of aptamer-based diagnostics, discuss the FDA regulatory mechanisms, and highlight the prospects and challenges in translating these studies into viable clinical diagnostic tools.

Functional nucleic acids in glycobiology: A versatile tool in the analysis of disease-related carbohydrates and glycoconjugates

As significant components of the organism, carbohydrates and glycoconjugates play indispensable roles in energy supply, cell signaling, immune modulation, and tumor cell invasion, and function as biomarkers since aberrance of them has been proved to be associated with the emergence and development of certain diseases. Functional nucleic acids (FNAs) have properties including easy-to-synthesize, good stability, good biocompatibility, low cost, and high programmability, they have attracted significant research attention and been incorporated into biosensors for detecting disease-related carbohydrates and glycoconjugates. This review summarizes the construction strategies and biosensing applications of FNAs-based biosensors in glycobiology in terms of target recognition and signal transduction. By illustrating the mechanisms and comparing the performances, the challenges and development opportunities in this area have been critically elaborated. We believe that this review will provide a better understanding of the role of FNAs in the analysis of disease-related carbohydrates and glycoconjugates, and inspire further discovery in fields that include glycobiology, chemical biology, clinical diagnosis, and drug development.

A direct and simple immobilization route for immunosensors by CNBr activation for covalent attachment of anti-leptin: obesity diagnosis point of view

Leptin is a peptide hormone produced in adipose tissue that works as an antiobesity hormone by balancing energy intake and expenditure. We aimed to develop an ultrasensitive electrochemical immunosensor based on a novel immobilization technique for the early detection of leptin-related diseases in this work. Although several methods for immobilizing antibodies to the biosensor recognition element are known, it is necessary to utilize novel, cost-effective, and less complicated immobilization procedures. When compared with currently utilized immobilization techniques for leptin measurement, this novel method is more efficient, easy to prepare, and sensitive, with a broad detection range. Indium tin oxide-coated polyethylene terephthalate (ITO-PET) sheets were used as the working electrode. ITO-PET sheets were modified using cyanogen bromide (CNBr) to immobilize the anti-leptin antibody through covalent interactions. Each stage of the proposed biosensors was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) methods, and extensive characterization studies were carried out. The designed biosensor has a wide linear detection range (0.05-100 pg/mL), low limits of detection (LOD) (0.0086 pg/mL) and quantification (LOQ) (0.0287 pg/mL). It was concluded that although it is disposable, the ITO-PET working electrode retains its activity even in repeated studies. In addition, the new immobilization procedure provided by CNBr for the designed biosensor fabrication can be effectively used in other biosensing applications.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-03096-w.

Organic–inorganic hybrid phosphite-participating S-shaped penta-CeIII incorporated tellurotungstate as electrochemical enzymatic hydrogen peroxide for β-D-glucose detection

Polyoxometalate chemistry has made rapid advances in innovative structural chemistry. The lower valence state and lone electron pair effect of subgroup-valence heteroatom Te(IV) can be introduced into the tungsten-oxygen system...

Recent advances of fluorescent biosensors based on cyclic signal amplification technology in biomedical detection

The cyclic signal amplification technology has been widely applied for the ultrasensitive detection of many important biomolecules, such as nucleic acids, proteins, enzymes, adenosine triphosphate (ATP), metal ions, exosome, etc. Due to their low content in the complex biological samples, traditional detection methods are insufficient to satisfy the requirements for monitoring those biomolecules. Therefore, effective and sensitive biosensors based on cyclic signal amplification technology are of great significance for the quick and simple diagnosis and treatment of diseases. Fluorescent biosensor based on cyclic signal amplification technology has become a research hotspot due to its simple operation, low cost, short time, high sensitivity and high specificity. This paper introduces several cyclic amplification methods, such as rolling circle amplification (RCA), strand displacement reactions (SDR) and enzyme-assisted amplification (EAA), and summarizes the research progress of using this technology in the detection of different biomolecules in recent years, in order to provide help for the research of more efficient and sensitive detection methods.

A simple immunosensor for thyroid stimulating hormone

Determination of thyroid-stimulating hormone (TSH) level in serum or plasma is defined as a sensitive method for the diagnosis of hyperthyroidism and hypothyroidism and also in many diseases thought to be related to TSH levels. In this study, a novel simple impedimetric immunosensor based on polyamidoamine dendrimer was developed. Anti TSH antibody was immobilized on the gold electrode by using cysteamine self-assembled monolayer strategy. In constructing the immunosensor, a polyamidoamine dendrimer was used to increase the surface area in which Antı-TSH was immobilized and glutaraldehyde was used as a cross-linker. After each immobilization step, the electrode surface was monitored by electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy and energy-dispersive X-ray spectroscopy techniques and optimization studies were performed. The reproducibility, repeatability, linearity and sensitivity of the immunosensor were examined. Also, the interference experiments for glucose, salts and proteins in serum were performed. The limit of detection and limit of quantification values of the proposed immunosensor were 0.026 mIUL^-1 and 0.086 mIUL^-1, respectively and it was able to detect the amount of TSH within a linear range of 0.1-0.6 mIUL^-1.

Hexameric to Trimeric Lanthanide-Included Selenotungstates and Their 2D Honeycomb Organic-Inorganic Hybrid Films Used for Detecting Ochratoxin A

Two types of organic-inorganic hybrid structure-related lanthanide (Ln)-included selenotungstates (Ln-SeTs) [H₂N(CH₃)₂]₁₁Na₇[Ce₄(H₂PTCA)₂(H₂O)₁₂(HICA)]₂[SeW₄O₁₇]₂[W₂O₅]₄[SeW₉O₃₃]₄·64H₂O (1, H₃PTCA = 1,2,3-propanetricarboxylic acid, H₂ICA = itaconic acid) and [H₂N(CH₃)₂]₆Na₄[Ln₄SeW₈(H₂O)₁₄(H₂PTCA)₂O₂₈] [SeW₉O₃₃]₂·31H₂O [Ln = Pr³⁺ (2), Nd³⁺ (3)] were obtained by Ln nature control. The primary frameworks of 1-3 are composed of trivacant Keggin-type [B-α-SeW₉O₃₃]^8- and [SeW₄O_m]^n- [Ln = Ce³⁺ (1), m = 17, n = 6; Ln = Pr³⁺ (2), Nd³⁺ (3), m = 18, n = 8] fragments bridged by organic ligands and Ln clusters. Intriguingly, Ln nature results in the degradation of hexameric 1 to trimeric 2-3. Besides, 1@DMDSA and 3@DMDSA composites (DMDSA·Cl = dimethyl distearylammonium chloride) were prepared through the cation exchange method, which were then reorganized to form two-dimensional (2D) honeycomb thin films by the breath figure method. Using these honeycomb thin films as electrode materials, the aptasensors were further established by utilizing methylene blue as an indicator and cDNA and Au nanoparticles as signal amplifiers to enhance the response signal so as to realize the purpose of ochratoxin A (OTA) detection. This work provides a new platform for detecting OTA and explores the application potential of POM-based composites in biological and clinical analyses.

Messengers of stress: Towards a cortisol sociology

In 2008, Timmermans and Haas called for a 'sociology of disease' to develop and challenge the sociology of health and illness. A sociology of disease, they argued, would take seriously the biological and physiological processes of disease in theorising health and illness. Building on two decades of Science and Technology Studies and feminist work on biological actors such as hormones and genes, we propose a 'cortisol sociology' to push further at this argument. As a 'messenger of stress', cortisol is key to understanding human and non-human health as a biosocial phenomenon. We argue that sociologists should engage with cortisol through critical yet open-minded reading of the relevant science and critical triangulation studies, and by tracking cortisol's movements from science into public worlds of biosensing and self-monitoring.

An electrochemical biosensor for direct detection of hepatitis C virus

This paper is aimed at the development of a biosensor for direct detection of Hepatitis C virus (HCV) surface antigen: envelope protein (E2). A recombinant LEL fragment of biological cell receptor CD81 and two short synthetic peptides imitating the fragment of LEL sequence of CD81 (linear and loop-like peptides) capable of specific binding to E2 were tested as molecular recognition elements of the biosensor. For this purpose the selected ligands were immobilized to the surface of a screen-printed electrode utilized as an electrochemical sensor platform. The immobilization parameters such as the ligand concentration and the immobilization time were carefully optimized for each ligand. Differential pulse voltammetry used to evaluate quantitatively binding of E2 to the ligands revealed their similar binding affinity towards E2. Thus, the linear peptide was selected as a less expensive and easily prepared ligand for the HCV biosensor preparation. The resulting HCV biosensor demonstrated selectivity towards E2 in the presence of interfering protein, conalbumin. Moreover, it was found that the prepared biosensor effectively detected E2 bound to hepatitis C virus-mimetic particles (HC VMPs) at LOD value of 2.1∙10^-5 mg/mL both in 0.01 M PBS solution (pH 7.4) and in simulated blood plasma.

2D Transition Metal Carbides (MXene) for Electrochemical Sensing: A Review

MXene, a novel class of 2-dimensional transition metal carbides has evolved as a promising material for various applications owing to its outstanding characteristics such as hydrophilicity, high electrical conductivity, surface area, and attractive topological structure. MXenes can form dispersion in common solvents and constitute composite with other nanomaterials, which can be utilized as effective transducers for molecular sensing. MXene-modified support materials, thus provide an intriguing platform for immobilization of target molecules onto their surface. The literature reveals that it has been increasingly utilized in the sensing of diverse types of analytes including glucose, pharmaceuticals, metals and dyes, cancer markers, pesticides, neurotransmitters, small valuable molecules, and so on. In this review, we summarize the recent updates in the MXene modified materials for sensing. For the convenience of our audience, we have distributed the analytes into categories and discussed them comprehensively. Not only we present the synthesis approach, electrochemical properties and surface chemistry of MXenes but also discussed briefly the current challenges and an outlook for future research in the related area.

Skin-Integrated Wearable Systems and Implantable Biosensors: A Comprehensive Review

Biosensors devices have attracted the attention of many researchers across the world. They have the capability to solve a large number of analytical problems and challenges. They are future ubiquitous devices for disease diagnosis, monitoring, treatment and health management. This review presents an overview of the biosensors field, highlighting the current research and development of bio-integrated and implanted biosensors. These devices are micro- and nano-fabricated, according to numerous techniques that are adapted in order to offer a suitable mechanical match of the biosensor to the surrounding tissue, and therefore decrease the body’s biological response. For this, most of the skin-integrated and implanted biosensors use a polymer layer as a versatile and flexible structural support, combined with a functional/active material, to generate, transmit and process the obtained signal. A few challenging issues of implantable biosensor devices, as well as strategies to overcome them, are also discussed in this review, including biological response, power supply, and data communication.

Recent advances in electroanalytical methods for the therapeutic monitoring of antiepileptic drugs: A comprehensive review

Frequency of seizures is often managed by a wide group of antiepileptic drugs. Regarding the pharmacokinetic variability, narrow targeted range, and difficulty of detecting signs of toxicity based on laboratory responses, therapeutic monitoring of antiepileptic drugs can play a pivotal role in optimizing the drug dosage. Electrochemical sensors and biosensors can facilitate analysis of these drugs due to their unique advantages such as fast analysis, sensitivity, selectivity, and low cost. This review article, for the first time, describes the recent advances in electrochemical sensors and biosensors developed for the analysis of antiepileptic drugs. General electrochemical measuring techniques and types of applied electrode substrates were described first. To simplify the work, various chemical and biological modifiers applied to improve the sensitivity and selectivity of the sensors were classified and explained briefly. Finally, the future prospective on the development of electrochemical platforms in the quantification of antiepileptic drugs will be presented.

Electrochemical Biosensors Based on S-Layer Proteins

Designing and development of electrochemical biosensors enable molecule sensing and quantification of biochemical compositions with multitudinous benefits such as monitoring, detection, and feedback for medical and biotechnological applications. Integrating bioinspired materials and electrochemical techniques promote specific, rapid, sensitive, and inexpensive biosensing platforms for (e.g., point-of-care testing). The selection of biomaterials to decorate a biosensor surface is a critical issue as it strongly affects selectivity and sensitivity. In this context, smart biomaterials with the intrinsic self-assemble capability like bacterial surface (S-) layer proteins are of paramount importance. Indeed, by forming a crystalline two-dimensional protein lattice on many sensors surfaces and interfaces, the S-layer lattice constitutes an immobilization matrix for small biomolecules and lipid membranes and a patterning structure with unsurpassed spatial distribution for sensing elements and bioreceptors. This review aims to highlight on exploiting S-layer proteins in biosensor technology for various applications ranging from detection of metal ions over small organic compounds to cells. Furthermore, enzymes immobilized on the S-layer proteins allow specific detection of several vital biomolecules. The special features of the S-layer protein lattice as part of the sensor architecture enhances surface functionalization and thus may feature an innovative class of electrochemical biosensors.

Aptamer-based biosensor for detecting carcinoembryonic antigen

Carcinoembryonic antigen (CEA), as one of the common tumor markers, is a human glycoprotein involved in cell adhesion and is expressed during human fetal development. Since the birth of human, CEA expression is largely inhibited, with only low levels in the plasma of healthy adults. Generally, CEA will overexpressed in many cancers, including gastric, breast, ovarian, lung, and pancreatic cancers, especially colorectal cancer. As one of the important tumor markers, the detection of CEA has great significance in differential diagnosis, condition monitoring and therapeutic evaluation of diseases. Conventional CEA testing typically uses immunoassay methods. However, immunoassay methods require complex and expensive instruments and professional personnel to operate. Moreover, radioactive element may cause certain damage to the human body, which limits their wide application. In the past few years, biosensors, especially aptamer-based biosensors, have attracted extensive attention due to their high sensitivity, good selectivity, high accuracy, fast response and low cost. This review briefly classifies and describes the advance in optical and electrochemical aptamer biosensors for CEA detection, also explains and compares their advantages and disadvantages.

A Bottom-Up Approach for Developing Aptasensors for Abused Drugs: Biosensors in Forensics

Aptamer-based point-of-care (POC) diagnostics platforms may be of substantial benefit in forensic analysis as they provide rapid, sensitive, user-friendly, and selective analysis tools for detection. Aptasensors have not yet been adapted commercially. However, the significance of the applications of aptasensors in the literature exceeded their potential. Herein, in this review, a bottom-up approach is followed to describe the aptasensor development and application procedure, starting from the synthesis of the corresponding aptamer sequence for the selected analyte to creating a smart surface for the sensitive detection of the molecule of interest. Optical and electrochemical biosensing platforms, which are designed with aptamers as recognition molecules, detecting abused drugs are critically reviewed, and existing and possible applications of different designs are discussed. Several potential disciplines in which aptamer-based biosensing technology can be of greatest value, including forensic drug analysis and biological evidence, are then highlighted to encourage researchers to focus on developing aptasensors in these specific areas.

Lectin biosensors in cancer glycan biomarker detection

Cancer has high incidence and it will continue to increase over the next decades. Detection and quantification of cancer-associated biomarkers is frequently carried out for diagnosis, prognosis and treatment monitoring at various disease stages. It is well-known that glycosylation profiles change significantly during oncogenesis. Aberrant glycans produced during tumorigenesis are, therefore, valuable molecules for detection and characterization of cancer, and for therapeutic design and monitoring. Although glycoproteomics has benefited from the development of analytical tools such as high performance liquid chromatography, two-dimensional gel and capillary electrophoresis and mass spectrometry, these approaches are not well suited for rapid point-of-care (POC) testing easily performed by medical staff. Lectins are biomolecules found in nature with specific affinities toward particular glycan structures and bind them thus forming a relatively strong complex. Because of this characteristic, lectins have been used in analytical techniques for the selective capture or separation of certain glycans in complex samples, namely, in lectin affinity chromatography, or to characterize glycosylation profiles in diverse clinical situations, using lectin microarrays. Lectin-based biosensors have been developed for the detection of specific aberrant and cancer-associated glycostructures to aid diagnosis, prognosis and treatment assessment of these patients. The attractive features of biosensors, such as portability and simple use make them highly suitable for POC testing. Recent developments in lectin biosensors, as well as their potential and pitfalls in cancer glycan biomarker detection, are presented in this chapter.

Liquid biopsy of circulating tumor DNA and biosensor applications

Circulating tumor DNA (ctDNA) as a class of liquid biopsy is a type of gene fragment that contains tumor-specific gene changes in body fluids such as human peripheral blood. More and more evidences show that ctDNA is an excellent tumor biomarker for diagnosis, prognosis, tumor heterogeneity and so on. ctDNA is a tumor code in the blood. Liquid biopsy of ctDNA is firstly summarized. Compared with the traditional detection technologies of ctDNA, the biosensor is an excellent choice for the detection of ctDNA because of its portability, sensitivity, specificity and ease of use. This review mainly evaluates various biosensors applied to the detection of ctDNA. We discuss the most commonly used bioreceptors to specifically identify and bind ctDNA, including complementary DNA (cDNA), peptide nucleic acid (PNA) and anti-5 MethylCytosines, and the biotransducers which convert biological signals to analysable signs. The review also discusses signal amplification strategies in biosensors to detect ctDNA.

Recent progress on cell-based biosensors for analysis of food safety and quality control

Food quality and safety has become a subject of major concern for authorities and professionals in the food supply chain. Rapid methods, particularly biosensors, have exceptional specificity and sensitivity, rapid response times, low cost, relatively compact size, and are user friendly to operate. Cell-based biosensors are portable, and provide the biological activity of the analyte suitable for an initial screening of food. In this overview, the utilization of cell-based biosensors for food safety and quality analyses, such as detecting toxins, foodborne pathogens, allergens, and evaluating toxicity and function are summarized. Our results will promote the future development of cell-based biosensors in the food field.