An electrochemical sensor based on carbon nanofiber and molecular imprinting strategy for dasatinib recognition.

Herein, we proposed a new approach to design a MIP-based electrochemical sensor with carbon nanofiber (CNF), which could improve its conductivities as well as electrode sensitivity and successful detection of dasatinib (DAS). CNFs are capable of forming high porosity with significant interconnected porous networks. The poly(2-hydroxyethyl-methacrylate-N-methacryloyl-L-tyrosine) (PHEMA-MATyr) copolymer was synthesized in the presence of both CNF and DAS by photopolymerization. After optimization of the parameters, the modified MIP-based electrochemical sensor demonstrated the ability to determine the DAS in the linear working range of 1.0 × 10-14-1.0 × 10-13 M for the standard solution and commercial serum samples with a LOD of 1.76 × 10-15 and 2.46 × 10-15, respectively. Good linearity for DAS was observed with correlation coefficients (r) of 0.996 and 0.997 for the standard solution and commercial serum samples, respectively. The recoveries of the DAS ranged from 99.45 % to 99.53 % for the tablet dosage form and commercial serum samples, with average relative standard deviations below 1.96 % in both cases. The proposed modified sensor demonstrated significant sensitivity and selectivity for the rapid determination of DAS in commercial serum samples and tablet form.

Investigation of Health Effects of Major Phenolic Compounds in Foods: Extraction Processes, Analytical Approaches and Applications.

The escalating costs of healthcare services and a growing awareness of personal health responsibilities have led individuals to explore natural methods alongside conventional medicines for health improvement and disease prevention. The aging global population is experiencing increased health needs, notably related to conditions like diabetes, heart disease, and hypertension. Lifestyle-related diseases, poor dietary habits, and sedentary lifestyles underscore the importance of foods containing nutrients that can aid in preventing and managing these diseases. Phenolic compounds, a fundamental group of phytochemicals, are prominent in the chemical diversity of the natural world and are abundant in functional foods. Widely distributed in various plant parts, these compounds exhibit important functional and sensory properties, including color, taste, and aroma. Their diverse functionalities, particularly antioxidant activity, play a crucial role in mitigating cellular oxidative stress, potentially reducing damage associated with serious health issues such as cardiovascular disease, neurodegenerative disea23ses, and cancer. Phenolic compounds exist in different forms, some combined with glycosides, impacting their biological effects and absorption. Approximately 8000 polyphenols isolated from plants offer significant potential for natural medicines and nutritional supplements. Therefore, their extraction process and selective and sensitive food determination are very important. This review focuses on the extraction processes, analytical methods, and health effects of major phenolic compounds in foods. The examination encompasses a comprehensive analysis of analytical approaches and their applications in elucidating the presence and impact of these compounds on human health.

Current Analytical Methods for the Sensitive Assay of New-Generation Ovarian Cancer Drugs in Pharmaceutical and Biological Samples.

Ovarian cancer, which affects the female reproductive organs, is one of the most common types of cancer. Since this type of cancer has a high mortality rate from gynaecological cancers, the scientific community shows great interest in studies on its treatment. Chemotherapy, radiotherapy, and surgical treatment methods are used in its treatment. In the absence of targeted treatments in these treatment methods, side effects occur in patients, and patients show resistance to the drug. In addition, the underlying causes of ovarian cancer are still not fully known. The scientific world thinks that genetic factors, environmental conditions, and consumed foods may cause this cancer. The most important factor in the treatment of ovarian cancer is early diagnosis. Therefore, the drugs used in the treatment of ovarian cancer are platinum-based anticancer drugs. In addition to these drugs, the most preferred treatment method recently is targeted treatment approaches using poly(adenosine diphosphate ribose) polymerase (PARP) inhibitors. In this review, studies on the sensitive analysis of the treatment methods of these new-generation drugs used in the treatment of ovarian cancer have been comprehensively examined. In addition, the basic features, structural aspects, and biological data of analytical methods used in treatments with new-generation drugs are explained. Analytical studies carried out in the literature in recent years aim to show future developments in how these new-generation drugs are used today and to guide future studies by comprehensively examining and explaining the structure-activity relationship, mechanism of action, toxicity, and pharmacokinetic studies. Finally, in this study, the methods used in the analysis of drugs used in the treatment of ovarian cancer and the studies conducted between 2015 and 2023 were discussed in detail.

A comparative study of electropolymerization and photopolymerization for the determination of molnupiravir and their application in an electrochemical sensor via computationally designed molecularly imprinted polymers.

A comparative analysis of molecularly imprinted polymers based on different synthesis techniques was performed for the recognition of molnupiravir (MOL). The polymerizations were performed with 3-thienyl boronic acid (3-TBA) as a functional monomer by electropolymerization (EP) and with guanine methacrylate (GuaM) as a functional monomer by photopolymerization (PP). Morphological and electrochemical characterizations of the developed sensors were investigated to verify the constructed sensors. Moreover, quantum chemical calculations were used to evaluate changes on the electrode surface at the molecular and electronic levels. The dynamic linear range of both designed sensors under optimized experimental conditions was found to be 7.5 × 10-12-2.5 × 10-10 M and 7.5 × 10-13-2.5 × 10-11 M for EP and PP, respectively. The effect of various interfering agents on MOL peak current was assessed for the selectivity of the study. In the presence of 100 times more interfering agents, the RSD and recovery values were determined. The RSD values of GuaM/MOL@MIP/GCE and poly(Py-co-3-PBA)/MOL@MIP/GCE sensors were found to be 1.99% and 1.72%, respectively. Furthermore, the recovery values of the MIP-based sensors were 98.18-102.69% and 98.05-103.72%, respectively. In addition, the relative selectivity coefficient (k') of the proposed sensor was evaluated, and it exhibited good selectivity for MOL with respect to the NIP sensor. The prepared sensor was successfully applied to determine MOL in commercial serum samples and capsule form. In conclusion, the developed sensors provided excellent reproducibility, repeatability, high sensitivity, and selectivity against the MOL molecule.

Highly selective and sensitive molecularly imprinted sensors for the electrochemical assay of quercetin in methanol extracts of Rubus sanctus and Fragaria vesca.

Quercetin (QUE) is a powerful antioxidant and one of the common phenolic compounds found in plants, vegetables, and fruits, which has shown many pharmacological activities. The complex nature of the matrix in which QUE is found and its importance and potential uses in diverse applications force the researchers to develop selective and sensitive sensors. In the present work, a novel molecularly imprinted polymer (MIP)-based electrochemical sensor was fabricated for the selective and sensitive determination of the QUE in plant extracts and food supplements. Tryptophan methacrylate (TrpMA) was chosen as the functional monomer, whereas the photopolymerization (PP) method was applied using a glassy carbon electrode (GCE). Electrochemical and morphological characterizations of the developed sensor (TrpMA@QUE/MIP-GCE) were performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The linear range of the developed sensor was determined to be in the range of 1.0-25 pM, while the limit of detection (LOD) was calculated to be 0.235 pM. In conclusion, The TrpMA@QUE/MIP-GCE sensor might be classified as a promising platform for selective and sensitive determination of QUE not only in plant extracts but also in commercial food supplements because of its reliability, reproducibility, repeatability, stability, and fast response time.

Development and Fabrication of a Molecularly Imprinted Polymer-Based Electroanalytical Sensor for the Determination of Acyclovir.

Acyclovir (ACV), a synthetic nucleoside derivative of purine, is one of the most potent antiviral medications recommended in the specific management of varicella-zoster and herpes simplex viruses. The molecularly imprinted polymer (MIP) was utilized to create an effective and specific electrochemical sensor using a straightforward photopolymerization process to determine ACV. The polymeric thin coating was developed using the template molecule ACV, a functional monomer acrylamide, a basic monomer 2-hydroxyethyl methacrylate, a cross-linker ethylene glycol dimethacrylate, and a photoinitiator 2-hydroxy-2-methyl propiophenone on the exterior of the glassy carbon electrode (GCE). Scanning electron microscopy, attenuated total reflectance-Fourier transform infrared spectroscopy, electrochemical impedance spectroscopy, and cyclic voltammetry were employed for the purpose of characterizing the constructed sensor (AM-ACV@MIP/GCE). Differential pulse voltammetry and a 5 mM ferrocyanide/ferricyanide ([Fe(CN)6]3-/4-) redox reagent were used to detect the ACV binding to the specific cavities on MIP. The study involves density functional theory (DFT) calculations, which were conducted to investigate template-functional monomer interactions thoroughly, calculate template-functional monomer interaction energies, and determine the optimal template/functional monomer ratio. DFT calculations were performed using Becke's three-parameter hybrid functional with the Lee-Yang-Parr correlation functional (B3LYP) method and 6-31G(d,p) basis set. The sensor exhibits linear performance throughout the concentration region 1 × 10-11 to 1 × 10-10 M, and the limit of detection and limit of quantification were 7.15 × 10-13 M and 2.38 × 10-12 M, respectively. For the electrochemical study of ACV, the sensor demonstrated high accuracy, precision, robustness, and a short detection time. Furthermore, the developed electrochemical sensor exhibited exceptional recovery in tablet dosage form and commercial human blood samples, with recoveries of 99.40 and 100.44%, respectively. The findings showed that the AM-ACV@MIP/GCE sensor would effectively be used to directly assess pharmaceuticals from actual specimens and would particularly detect ACV compared to structurally similar pharmaceutical compounds.

A novel electrochemical sensor based on a molecularly imprinted polymer for highly selective and sensitive determination of rutin from herbal supplements and plant extracts.

Rutin (RUT), a natural flavonoid with various beneficial pharmacological actions such as cardioprotective, antioxidant, anti-inflammatory, neuroprotective, etc., is found in the content of many plants that are consumed daily. Due to the healthful effects, RUT is also included in the composition of various herbal supplement samples. Therefore, it is highly important to develop a sensor with high selectivity and sensitivity to determine RUT in complex samples. In this study, it was aimed to take advantage of the cheap, easy, and sensitive nature of electrochemistry and, in addition, to improve the selectivity. For this purpose, the functional monomer selected in the fabricated molecularly imprinted polymer (MIP) was N-methacryloyl-L-aspartic acid (MA-Asp) while photopolymerization (PP) was applied as the polymerization route. After completing critical optimization steps, the developed sensor (MA-Asp@RUT/MIP-GCE) was characterized electrochemically and morphologically. As a result of analytical performance evaluation in standard solution, the linear response of the sensor was found in the concentration range between 1 and 10 pM with a detection limit of 0.269 pM. The recovery studies from plant extract and commercial herbal supplement samples emphasized accuracy and applicability. In imprinting factor studies figuring out quite good selectivity, molecules with a structure similar to RUT were selected as competitors to prove the affinity of the sensor against RUT. Consequently, the MA-Asp@RUT/MIP-GCE sensor offers a more sensitive and selective method thanks to its indirect analysis approach and also stands out with the diversity of its real sample application compared to other available studies.

The sensor applications for prostate and lung cancer biomarkers in terms of electrochemical analysis.

Prostate and lung cancers are the most common types of cancer and affect a large part of the population around the world, causing deaths. Therefore, the rapid identification of cancer can profoundly impact reducing cancer-related death rates and protecting human lives. Significant resources have been dedicated to investigating new methods for early disease detection. Cancer biomarkers encompass various biochemical entities, including nucleic acids, proteins, sugars, small metabolites, cytogenetic and cytokinetic parameters, and whole tumor cells in bodily fluids. These tools can be utilized for various purposes, such as risk assessment, diagnosis, prognosis, treatment efficacy, toxicity evaluation, and predicting a return. Due to these versatile and critical purposes, there are widespread studies on the development of new, sensitive, and selective approaches for the determination of cancer biomarkers. This review illustrates the significant lung and prostate cancer biomarkers and their determination utilizing electrochemical sensors, which have the advantage of improved sensitivity, low cost, and simple analysis. Additionally, approaches such as improving sensitivity with nanomaterials and ensuring selectivity with MIPs are used to increase the performance of the sensor. This review aims to overview the most recent electrochemical biosensor applications for determining vital biomarkers of prostate and lung cancers in terms of nanobiosensors and molecularly imprinted polymer (MIP)-based biosensors.

The Effect of Polymerization Techniques on the Creation of Molecularly Imprinted Polymer Sensors and Their Application on Pharmaceutical Compounds.

Molecularly imprinted polymers (MIPs) have become more prevalent in fabricating sensor applications, particularly in medicine, pharmaceuticals, food quality monitoring, and the environment. The ease of their preparation, adaptability of templates, superior affinity and specificity, improved stability, and the possibility for downsizing are only a few benefits of these sensors. Moreover, from a medical perspective, monitoring therapeutic medications and determining pharmaceutical compounds in their pharmaceutical forms and biological systems is very important. Additionally, because medications are hazardous to the environment, effective, quick, and affordable determination in the surrounding environment is of major importance. Concerning a variety of performance criteria, including sensitivity, specificity, low detection limits, and affordability, MIP sensors outperform other published technologies for analyzing pharmaceutical drugs. MIP sensors have, therefore, been widely used as one of the most crucial techniques for analyzing pharmaceuticals. The first part of this review provides a detailed explanation of the many polymerization techniques that were employed to create high-performing MIP sensors. In the subsequent section of the review, the utilization of MIP-based sensors for quantifying the drugs in their pharmaceutical preparation, biological specimens, and environmental samples are covered in depth. Finally, a critical evaluation of the potential future research paths for MIP-based sensors clarifies the use of MIP in pharmaceutical fields.

Designing an electrochemical sensor based on ZnO nanoparticle-supported molecularly imprinted polymer for ultra-sensitive and selective detection of sorafenib.

BACKGROUND: Sorafenib (SOR) is a multikinase inhibitor anticancer drug that is used in treating non-small cell lung cancer. In this work, we focused on developing nanomaterial-supported smart porous interfaces by following the molecular imprinting approach for the selective determination of SOR. Determination-based studies in the literature for SOR are limited, and they are chromatographic techniques-based; hence, there is a need in the literature to elaborate the selective and sensitive analysis/monitoring of SOR in both biological and pharmaceutical samples with more studies. RESULTS: The results showed that adding ZnO NPs enhanced the signal five times compared to the solo molecularly imprinted polymer (MIP). Under the optimized conditions, ZnO/AMPS@MIP-GCE showed a linear response in the concentration range between 1.0 × 10-12 and 1.0 × 10-11 M with LOD and LOQ values of 2.25 × 10-13 M and 7.51 × 10-13 M, respectively, in the serum sample. The selectivity study was conducted against common cations, anions, and compounds such as dopamine, paracetamol, ascorbic acid, and uric acid. Also, the imprinting factor (IF) analysis was performed on selected drug substances having structural similarities to SOR and the relative IF values of regorafenib, leflunomide, teriflunomide, nilotinib, axitinib, and dasatinib indicated the selectivity of the developed sensor for SOR. Finally, ZnO/AMPS@MIP-GCE was implemented to determine SOR in the spiked commercial human serum samples and tablet dosage form with bias% between -0.43 and + 0.66. SIGNIFICANCE AND NOVELTY: This study is the first electrochemical study for the determination of SOR, and thanks to the ZnO NPs supported MIP sensor, it stands out in terms of both high sensitivity and superior selectivity. Also, this designed sensor provides controlled orientation of the template and complete removal of templates in a one-step process, allowing extremely low detection and quantification limits.

Development of highly selective and sensitive molecularly imprinted polymer-based electrochemical sensors for tolvaptan assay in tablets and serum.

In this research, two different molecularly imprinted polymer (MIP)-based electrochemical sensors were proposed for the determination of tolvaptan (TOL). Photopolymerization (PP) and thermal polymerization (TP) techniques were developed for the determination of TOL. The advantages of MIP were used to design an electrochemical sensor for selective and sensitive determination of TOL. TOL was determined on a glassy carbon electrode (GCE) using differential pulse voltammetry (DPV) for both techniques. Some important parameters affecting the sensor efficiency, such as template/monomer ratio, PP and TP time, drop volume, removal solutions, removal and rebinding time, etc., were optimized. The surface characterization of the proposed MIP-based electrochemical sensors was carried out with electrochemical characterization by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) methods. It was extended with the scanning electron microscopy (SEM) technique. Under optimal conditions, the developed sensors showed good linearity between 1.0 × 10-11 M and 1.0 × 10-10 M, and 2.5 × 10-11 M and 2.5 × 10-10 M for PP and TP, respectively. Low detection limits (2.89 × 10-12 M (PP) and 1.88 × 10-13 M (TP)) were also obtained for TOL determination. The applicability of the proposed sensor was evaluated using tablet and commercial human serum samples. Interference and imprinting factor studies verified the selectivity and specificity of the proposed sensors, and the efficiency of the sensors was verified using an unprinted polymer for comparison at each step.

The electrochemical quantitation method for sugammadex via a molecularly imprinted polymer-based sensor.

Sugammadex (SUG) is a synthetically modified γ-cyclodextrin derivative used in hospitals after surgeries to reverse the neuromuscular blockade induced by rocuronium or vecuronium. In this study, we aimed to develop the first electroanalytical quantification method for sugammadex by using molecular imprinting (MIP) via the electropolymerization (EP) technique. An EP-MIP film was formed by EP on a screen-printed gold electrode (SPAuE) and a new electrochemical sensor, EP-MIP(SUG)/SPAuE, was fabricated using the 4-aminophenol monomer with copper ions to enhance the MIP-binding site. Surface and electrochemical characterization of the EP-MIP(SUG)/SPAuE sensor have been done via scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). After screening and optimization studies were carried out to fabricate a MIP-based electrochemical sensor, the analytical performance of EP-MIP(SUG)/SPAuE and the validation parameters were tested according to the ICH guidelines. The specificity/selectivity of the developed sensor has been shown by using common interferents found in the biological fluids and also molecules having similar structures, such as α-cyclodextrin, ß-cyclodextrin, and γ-cyclodextrin. As a result, a quantitative analysis method has been developed and validated by using the EP-MIP(SUG)/SPAuE sensor in the concentration range of 0.1-1.0 pM with very high sensitivity (limit of detection: 27.3 fM). The applicability of the method has been shown for bulk drug substances, pharmaceutical dosage forms, and commercial serum samples with good recovery and RSD% results. The EP-MIP(SUG)/SPAuE is the first electrochemical sensor developed for the determination of sugammadex serving the aims of simplicity, short analysis time, and low cost, and has the potential to be adapted in the future as a portable and/or wearable sensor via miniaturization.

A molecularly imprinted polymer-based electrochemical sensor for the determination of tofacitinib.

Tofacitinib citrate (TOF) is a Janus kinase-3 inhibitor used for rheumatoid arthritis treatment. In this study, a molecularly imprinted polymer (MIP)-based sensor was produced using acrylamide as the functional monomer via photopolymerization technique for the electrochemical determination of TOF. This study is the first one to explain the electrochemical determination of TOF with a highly selective MIP-based sensor. The surface characterization of the MIP-based sensor was performed with scanning electron microscopy and energy-dispersive X-ray spectroscopy methods, and it was expanded with electrochemical characterization by cyclic voltammetry and electrochemical impedance spectroscopy (EIS) methods. TOF determination was performed using differential pulse voltammetry (DPV) and EIS methods in standard solution and spiked serum sample in the linear range between 1×10-11 M and 1×10-10 M. Very low limit of detection and limit of quantification values were found, confirming the sensitivity of the sensor. Recovery analysis with spiked serum and tablet samples verified the sensor's accuracy and applicability using DPV and EIS methods. The selectivity of the sensor was confirmed with imprinting factor and interference studies, and the sensor performance was controlled using non-imprinted polymer for comparison at every step.

Designing of ZnO nanoparticles oriented interface imprinted electrochemical sensor for fluoxetine detection.

This study represents nanoparticle-based well-oriented recognition sites via interface imprinting, followed by selective and sensitive determination of fluoxetine (FLX). Herein, FLX was firstly immobilized onto ZnO NPs, and then polymerization was carried out with MAPA, HEMA, and EGDMA on the glassy carbon electrode via photopolymerization. After the etching of ZnO with and 10 mM HCI solution, a porous structure with recognition sites for FLX was constructed onto surface. The characterization of the electrochemical sensor was accomplished by utilizing CV, EIS, ATR-FTIR AFM, and SEM analysis. The DPV was used to determine FLX in standard solution, serum sample, and tap water. The effect of FLX concentration variation was studied using the DPV in the range of 1.0 × 10-11 M to 1.0 × 10-10 M with a detection limit of 2.67 × 10-12 M. This sensor showed specific recognition toward template, and more than 90% of its original response was retained after being stored in the desiccator at R.T. for 5 days. This technique has proven to be a powerful, highly selective, and sensitive tool for the rapid detection of FLX in tap water and spike serum samples.

Aptamers as Novel Binding Molecules on an Antimicrobial Peptide-Armored Composite Hydrogel Wound Dressing for Specific Removal and Efficient Eradication of Pseudomonas aeruginosa.

Here we present for the first time a potential wound dressing material implementing aptamers as binding entities to remove pathogenic cells from newly contaminated surfaces of wound matrix-mimicking collagen gels. The model pathogen in this study was the Gram-negative opportunistic bacterium Pseudomonas aeruginosa, which represents a considerable health threat in hospital environments as a cause of severe infections of burn or post-surgery wounds. A two-layered hydrogel composite material was constructed based on an established eight-membered focused anti-P. aeruginosa polyclonal aptamer library, which was chemically crosslinked to the material surface to form a trapping zone for efficient binding of the pathogen. A drug-loaded zone of the composite released the C14R antimicrobial peptide to deliver it directly to the bound pathogenic cells. We demonstrate that this material combining aptamer-mediated affinity and peptide-dependent pathogen eradication can quantitatively remove bacterial cells from the "wound" surface, and we show that the surface-trapped bacteria are completely killed. The drug delivery function of the composite thus represents an extra safeguarding property and thus probably one of the most important additional advances of a next-generation or smart wound dressing ensuring the complete removal and/or eradication of the pathogen of a freshly infected wound.

A Comprehensive Overview of Sensors Applications for the Diagnosis of SARS-CoV-2 and of Drugs Used in its Treatment.

During the COVID-19 process, determination-based analytical chemistry studies have had a major place at every stage. Many analytical techniques have been used in both diagnostic studies and drug analysis. Among these, electrochemical sensors are frequently preferred due to their high sensitivity, selectivity, short analysis time, reliability, ease of sample preparation, and low use of organic solvents. For the determination of drugs used in the SARS-CoV-2, such as favipiravir, molnupiravir, ribavirin, etc., electrochemical (nano)sensors are widely used in both pharmaceutical and biological samples. Diagnosis is the most critical step in the management of the disease, and electrochemical sensor tools are widely preferred for this purpose. Diagnostic electrochemical sensor tools can be biosensor-, nano biosensor-, or MIP-based sensors and utilize a wide variety of analytes such as viral proteins, viral RNA, antibodies, etc. This review overviews the sensor applications in SARS-CoV-2 in terms of diagnosis and determination of drugs by evaluating the most recent studies in the literature. In this way, it is aimed to compile the developments so far by shedding light on the most recent studies and giving ideas to researchers for future studies.

Approaches and Challenges for Biosensors for Acute and Chronic Heart Failure.

Heart failure (HF) is a cardiovascular disease defined by several symptoms that occur when the heart cannot supply the blood needed by the tissues. HF, which affects approximately 64 million people worldwide and whose incidence and prevalence are increasing, has an important place in terms of public health and healthcare costs. Therefore, developing and enhancing diagnostic and prognostic sensors is an urgent need. Using various biomarkers for this purpose is a significant breakthrough. It is possible to classify the biomarkers used in HF: associated with myocardial and vascular stretch (B-type natriuretic peptide (BNP), N-terminal proBNP and troponin), related to neurohormonal pathways (aldosterone and plasma renin activity), and associated with myocardial fibrosis and hypertrophy (soluble suppression of tumorigenicity 2 and galactin 3). There is an increasing demand for the design of fast, portable, and low-cost biosensing devices for the biomarkers related to HF. Biosensors play a significant role in early diagnosis as an alternative to time-consuming and expensive laboratory analysis. In this review, the most influential and novel biosensor applications for acute and chronic HF will be discussed in detail. These studies will be evaluated in terms of advantages, disadvantages, sensitivity, applicability, user-friendliness, etc.

Comparative study of electrochemical-based sensors and immunosensors in terms of advantageous features for detection of cancer biomarkers.

Cancer, becoming increasingly common globally, has a high mortality rate. Despite the much research on diagnosis and treatment methods, the benefits of technological developments, and newly developed sensor devices, cancer is still one of the leading causes of death worldwide. Early detection using powerful and noninvasive tools could be a future focus for prognosis and treatment follow-up. Therefore, electrochemical biosensors can be a strong choice for the detection of cancer biomarkers (such as alpha-fetoprotein, cytochrome c, prostate-specific antigen, myoglobin, carcinoembryonic antigen, alpha-fetoprotein, a cancer antigen, epidermal growth factor receptor, vascular endothelial growth factor, circulating tumor cell, and breast cancer antigen 1/2) due to their advantages such as high sensitivity, excellent selectivity, low cost, short analysis time, and simplicity. Furthermore, electrochemical biosensors are better suited for point-of-care applications due to their mass production and miniaturization ease. This review provides an overview of different electrochemical measurement techniques, bioreceptor surfaces, signal production and amplification, and the integration of electrochemical-modified sensors. Cancer biomarkers based on electrochemical biosensors were given in detail. In addition, studies with MIP-based sensors and immunosensors have been extensively discussed. Integrating electrochemical biosensors with cancer biomarkers was also emphasized as a new research trend. Finally, we provide an overview of current advances in measuring and analyzing cancer biomarkers using electrochemical biosensors and detail current challenges and future perspectives.

Detection of Axitinib Using Multiwalled Carbon Nanotube-Fe2O3/Chitosan Nanocomposite-Based Electrochemical Sensor and Modeling with Density Functional Theory.

In this study, axitinib (AXI), a potent and selective inhibitor of vascular endothelial growth factor receptor (VEGFR) tyrosine kinase and used as a second-generation targeted drug, was investigated electrochemically under optimized conditions using multiwalled carbon nanotubes/iron(III) oxide nanoparticle-chitosan nanocomposite (MWCNT/Fe2O3@chitosan NC) modified on the glassy carbon electrode (GCE) surface. Characterization of the modified electrode was performed using scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The adsorptive stripping differential pulse voltammetric (AdSDPV) technique was used for the sensitive, rapid, and precise detection of AXI. The current peak obtained with the MWCNT/Fe2O3@chitosan NC modified electrode was 23 times higher compared to the bare electrode. The developed modified electrode showed excellent electrocatalytic activity in AXI oxidation. Under optimized conditions, the effect of supporting electrolyte and pH was investigated, and 0.1 M H2SO4 was chosen as the electrolyte with the highest peak current for the target analyte. In the concentration range of MWCNT/Fe2O3@chitosan NC/GCE, 6 × 10-9 and 1 × 10-6 M, the limit of detection (LOD) and limit of quantification (LOQ) values were calculated to be 0.904 and 0.0301 pM, respectively. Tablet and serum samples were used for the applicability of the developed sensor, relative standard deviation (RSD) values for all samples were below 2%, and the recovery results were 99.23 and 101.84%, respectively. The MWCNT/Fe2O3@chitosan NC/GCE designed to determine AXI demonstrated the applicability, selectivity, precision, and accuracy of the sensor. The mechanism of electron transfer from the modified GCE surface to the analyte solution is studied via modeling the modified GCE surface by the density functional theory (DFT) method at B3LYP/6-311+g(d,p) and M062X/6-31g(d,p) levels. We observed that the iron oxide nanoparticles play an important role in channeling electron flow from the analyte solution to the MWCNT-coated GCE electrode surface. Adsorption of the nanocomposite material onto the GCE surface occurs via strong electrostatic interactions, including ionic and hydrogen bond formations. During the adsorption-controlled oxidation process of the axitinib, the electrons are transferred via the highest occupied molecular orbital (HOMO) localized on the iron oxide moiety to the lowest unoccupied molecular orbital (LUMO) of the MWCNT/GCE surface.

A semi-covalent molecularly imprinted electrochemical sensor for rapid and selective detection of tiotropium bromide.

Tiotropium bromide (TIO) is a long-acting bronchodilator used in the treatment of chronic obstructive pulmonary disease (COPD) and asthma. Specifically, it is used to prevent patients from worsening breathing difficulties. In this study, a new TIO-imprinted electrochemical sensor was designed to detect TIO in serum and pharmaceutical samples. Methacryloyl-L-histidine-cobalt(II) [MAH-Co(II)] has been used as a metal-chelating monomer for synthesizing selective molecularly imprinted polymer (MIP). MIP film has been developed on glassy carbon electrodes using MAH-Co(II) as the functional monomer, 2-hydroxyethyl methacrylate (HEMA) as the basic monomer, and ethylene glycol dimethacrylate (EGDMA) as the cross-linker in the photopolymerization method. The surface characterization of the developed MAH-Co(II)@MIP/GCE electrochemical sensor was done using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Also, the electrochemical behavior of the sensor was provided by differential pulse voltammetry (DPV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) techniques. Under optimized experimental conditions, the linearity range was in the range of 10-100 fM, and the limit of detection (LOD) and limit of quantitation (LOQ) values were calculated as 2.73 fM and 9.75 fM, respectively. The MAH-Co(II)@MIP/GCE sensor was used to precisely determine TIO in capsule and commercial serum samples. The results demonstrated that the MIP could specifically recognize TIO compared to structurally related drugs and could be reliably applied to the direct determination of drugs from real samples.