Electrochemical Biosensors

Colorectal cancer (CRC) is a type of malignant disease that affects the large intestine (colon) and rectum. The CRC is among the causes of the highest mortality rates worldwide, so its rapid and sensitive early diagnosis is substantial. In the last few decades, CRC detection by electrochemical biosensors has progressed significantly due to their amenability and cost-effectiveness. Various electrochemical sensing strategies have been implemented, involving CRC biomarkers, such as protein, gene, or even CRC cells, that play a crucial role in screening tests, treatment, and prognosis. Electrochemical sensors are favored in this regard, owing to their ability to provide real-time, on-site detection with a straightforward preparation of samples. The present work provides an overview from the basic concepts to the recent research advances in electrochemical CRC biosensors for the management of patients. The review covers the importance of CRC detection, an introduction to electrochemical sensors, and cutting-edge electrochemical CRC biosensors. Further, challenges, limitations, and future research directions in developing and applying electrochemical sensing tools for CRC biomarkers are also comprehensively discussed. By consolidating the current research status, the present work aims to inspire further innovation in the development of electrochemical CRC biosensors. The insights presented here are expected to contribute to advancing more efficient, accessible diagnostic devices for CRC in the future.

Cancer is a result of uncontrolled cell growth with the potential to damage or spread to another part of the body. It is the deadliest disease in the world; therefore, rapid and sensitive detection is essential to fight it. In the past few decades, many diagnosis tools have been developed to detect cancer and monitor therapy progress. Among them, electrochemical biosensor showed the promising significance due to its capability of early detection, selectivity, sensitivity, flexibility, portability and cost-effectiveness. The performance of the electrochemical sensor depends on the sensor surface engineering as well as development techniques based on the types of biomarkers. This review covers the importance of cancer diagnosis, the basic concept of the electrochemical biosensor, design strategy of biosensors including surface engineering and the state-of-the-art for different types of biomarker detection. Additionally, the limitations and advantages of different types of biosensors were parallelly explained. Finally, the future direction for the advancement of electrochemical biosensor is comprehensively discussed. The author trusts that the insights thus explained will lead to further research in the scholarly community aimed at expanding theoretical knowledge and pragmatic innovation in electrochemical sensing devices for cancer detection. Such research findings are anticipated to facilitate high-end developments both in the theoretical area and the application. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

With the rise in public health awareness, research on point-of-care testing (POCT) has significantly advanced. Electrochemical biosensors (ECBs) are one of the most promising candidates for the future of POCT due to their quick and accurate response, ease of operation, and cost effectiveness. This review focuses on the use of metal nanoparticles (MNPs) for fabricating ECBs that has a potential to be used for POCT. The field has expanded remarkably from its initial enzymatic and immunosensor-based setups. This review provides a concise categorization of the ECBs to allow for a better understanding of the development process. The influence of structural aspects of MNPs in biocompatibility and effective sensor design has been explored. The advances in MNP-based ECBs for the detection of some of the most prominent cancer biomarkers (carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), Herceptin-2 (HER2), etc.) and small biomolecules (glucose, dopamine, hydrogen peroxide, etc.) ha...

Bio-electrochemical systems (BES) have emerged as a promising technology for sustainable energy conversion and environmental applications. This review provides a comprehensive analysis of the fundamental principles of BES, including microbial metabolism, electron transfer mechanisms, and electrode reactions. The discussion extends to the diverse applications of BES technology, such as environmental remediation, bio-electrosynthesis, and microbial fuel cells (MFCs). By integrating theoretical insights with real-world case studies, this review highlights the potential of BES in advancing renewable energy and environmental sustainability. Furthermore, it examines current challenges and future directions in BES research, emphasizing opportunities for technological innovation and scalability. This review serves as a valuable resource for researchers, engineers, and practitioners seeking to enhance their understanding of bio-electrochemical energy conversion and explore its transformative applications in various sectors.

 Synthesis and incorporation of Au-NPs carrying a thiolated catechol in nanocomposite carbon paste electrodes.  Highly sensitive carbon nanotube-based amperometric sensor towards uranium in water.  Excellent supramolecular recognition between uranyl ion and catechol, with a detection limit of 0.49 g•L -1 .  Feasibility of the present sensing platform in real mine samples.

Point of Care (POC) diagnosis provides an effective approach for controlling and managing Neglected Tropical Diseases (NTDs). Electrochemical biosensors are well-suited for molecular diagnostics due to their high sensitivity, cost-effectiveness, and ease of integration into POC devices. Schistosomiasis is a prominent NTD highly prevalent in Africa, Asia, and Latin America, with significant socioeconomic implications such as discrimination, reduced work capacity, or mortality, perpetuating the cycle of poverty in affected regions worldwide. This review explores recent advancements in nanoparticle-based electrochemical biosensors for disease diagnosis, specifically focusing on the schistosome parasite. The synthesis processes and advantages of microwave-assisted preparation of metal oxide nanoparticles are highlighted, showcasing improved purity and energy efficiency compared to traditional combustion methods. In detection prototypes, Schistosome Egg Antigen (SEA) derived from Schistosome mansoni eggs obtained from primary and secondary hosts were evaluated using direct Enzyme-Linked Immunosorbent Assay (ELISA) to measure antibody concentrations in the primary and secondary hosts post-injection. Biosensor system was then developed by modifying developed electrodes with Gold Nanopartcicles (AuNP), Aluminium Gallium Nitride/Gallium Nitride (AlGaN/GaN), Mercaptopropyltrimethoxysilane/Gold Nanoparticles (MPTS/ AuNPs) or metal oxide nanoparticles in conjugation with schistosome antibodies, registering current response on interactions with SEA, via cyclic voltammetry (CV), differential pulse voltammetry (DPV), Electrochemical Impedance Spectroscopy (EIS), Amperometry (A) and other electrochemical techniques. This review provides a summary of various constructions of electrochemical biosensors for detecting schistosomiasis.

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Alkaline phosphatase (ALP), which catalyzes the dephosphorylation process of proteins, nucleic acids, and small molecules, can be found in a variety of tissues (intestine, liver, bone, kidney, and placenta) of almost all living organisms. This enzyme has been extensively used as a biomarker in enzyme immunoassays and molecular biology. ALP is also one of the most commonly assayed enzymes in routine clinical practice. Due to its close relation to a variety of pathological processes, ALP’s abnormal level is an important diagnostic biomarker of many human diseases, such as liver dysfunction, bone diseases, kidney acute injury, and cancer. Therefore, the development of convenient and reliable assay methods for monitoring ALP activity/level is extremely important and valuable, not only for clinical diagnoses but also in the area of biomedical research. This paper comprehensively reviews the strategies of optical and electrochemical detection of ALP and discusses the electrochemical techn...

A piezoelectric immunosensor based on gold nanoparticles (AuNPs) co-immobilized on a dithiol-modified surface is proposed for detection of human cardiac troponin T (TnT). Anti-human troponin T (anti-TnT) antibodies were covalently immobilized on the nanostructured electrode surface by thiol-aldehyde linkages. In a homogeneous bulk solution, TnT was captured by anti-TnT immobilized on the QCM electrode. Cyclic voltammetry studies were used to characterize the AuNPs layer on the electrode surface and the anti-TnT immobilization steps. The QCM-flow immunosensor exhibited good reliability, measuring concentrations of TnT from 0.003 to 0.5 ng mL −1 in human serum with high linearity (r = 0.989; p < 0.01). The immunosensor exhibited a 7% coefficient of variation and 0.0015 ng mL −1 limit of detection, indicating a high reproducibility and sensitivity. The proposed QCM nanostructured immunosensor is easy to use and has promising potential in the diagnosis of acute myocardial infarction due to its speed and high sensitivity.

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, includin...

A disposable dual-output biosensor to detect program death-ligand 1 (PD-L1) was developed for immunotherapy progress monitoring and early cancer detection in a single experimental setup. The aptamer probe was assembled on rGO composited with carboxylated terthiophene polymer (rGO-pTBA) to specifically capture PD-L1 protein labeled with a new redox mediator, ortho-amino phenol para sulphonic acid, for amperometric detection. Each sensing layer was characterized through electrochemical and surface analysis experiments, then confirmed the sensing performance. The calibration plots for the standard PD-L1 protein detection revealed two dynamic ranges of 0.5-100.0 pM and 100.0-500.0 pM, where the detection limit was 0.20 ± 0.001 pM (RSD ≤5.2%) by amperometry. The sensor reliability was evaluated by detecting A549 lung cancer cell-secreted PD-L1 and clinically relevant serum levels of soluble PD-L1 (sPD-L1) using both detection methods. In addition, therapeutic trials were studied through the quantification of sPD-L1 levels for a small cohort of lung cancer patients. A significantly higher level of sPD-L1 was observed for patients (221.6-240.4 pM) compared to healthy individuals (16.2-19.6 pM). After immunotherapy, the patients' PD-L1 level decreased to the range of 126.7-141.2 pM. The results indicated that therapy monitoring was successfully done using both the proposed methods. Additionally, based on a comparative study on immune checkpoint-related proteins, PD-L1 is a more effective biomarker than granzyme B and interferon-gamma.

With the rise in public health awareness, research on point-of-care testing (POCT) has significantly advanced. Electrochemical biosensors (ECBs) are one of the most promising candidates for the future of POCT due to their quick and accurate response, ease of operation, and cost effectiveness. This review focuses on the use of metal nanoparticles (MNPs) for fabricating ECBs that has a potential to be used for POCT. The field has expanded remarkably from its initial enzymatic and immunosensor-based setups. This review provides a concise categorization of the ECBs to allow for a better understanding of the development process. The influence of structural aspects of MNPs in biocompatibility and effective sensor design has been explored. The advances in MNP-based ECBs for the detection of some of the most prominent cancer biomarkers (carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), Herceptin-2 (HER2), etc.) and small biomolecules (glucose, dopamine, hydrogen peroxide, etc.) ha...

The SARS-CoV-2 virus is still causing a dramatic loss of human lives worldwide, constituting an unprecedented challenge for the society, public health and economy, to overcome. The up-to-date diagnostic tests, PCR, antibody ELISA and Rapid Antigen, require special equipment, hours of analysis and special staff. For this reason, many research groups have focused recently on the design and development of electrochemical biosensors for the SARS-CoV-2 detection, indicating that they can play a significant role in controlling COVID disease. In this review we thoroughly discuss the transducer electrode nanomaterials investigated in order to improve the sensitivity, specificity and response time of the as-developed SARS-CoV-2 electrochemical biosensors. Particularly, we mainly focus on the results appeard on Au-based and carbon or graphene-based electrodes, which are the main material groups recently investigated worldwidely. Additionally, the adopted electrochemical detection techniques are also discussed, highlighting their pros and cos. The nanomaterial-based electrochemical biosensors could enable a fast, accurate and without special cost, virus detection. However, further research is required in terms of new nanomaterials and synthesis strategies in order the SARS-CoV-2 electrochemical biosensors to be commercialized.

Albendazole (ABZ) is a widely used anthelmintic drug for the treatment of parasitic worms and other diseases. The bulk electrolysis reduction reaction of albendazole (ABZ) was carried out in ammonium bromide‐acetonitrile solution under stirring conditions. The reduction of albendazole at gold electrode gave three non‐reversible waves. The average value of the electron transfer coefficient (nα) was found to be 0.505. The measured diffusion coefficient (D) had a value of 0.143×10−8 cm2 s−1. The bulk electrochemical reduction of ABZ products were characterized using liquid chromatography‐mass spectroscopy. Three cyclic voltammetry reduction waves were observed using a gold electrode and three chromatographic peaks were observed using liquid chromatography‐ Mass spectrometry. The observed results suggested that the second and third reduction steps occurred at the sulfur functional group of albendazole.

In this study, graphene oxide was electrochemically deposited and reduced on a graphite sheet. The electrode surface morphology was studied by scanning electron microscopy. The performance of the modified electrode in detecting dopamine was investigated. The results indicate that the electrodeposition of reduced graphene oxide onto the electrode surface increases the dopamine oxidation current, decreases the overpotential, and reduces the ...

Recently, the low-cost effective biosensing systems based on advanced nanomaterials have received a key attention for development of novel assays for rapid and sequence-specific nucleic acid detection. The electrochemical biosensor based on reduced graphene oxide (rGO) modified disposable pencil graphite electrodes (PGEs) were developed herein for electrochemical monitoring of DNA, and also for monitoring of biointeraction occurred between anticancer drug, Daunorubicin (DNR), and DNA. First, rGO was synthesized chemically and characterized by using UV-Vis, TGA, FT-IR, Raman Spectroscopy and SEM techniques. Then, the quantity of rGO assembling onto the surface of PGE by passive adsorption was optimized. The electrochemical behavior of rGO-PGEs was examined by cyclic voltammetry (CV). rGO-PGEs were then utilized for electrochemical monitoring of surface-confined interaction between DNR and DNA using differential pulse voltammetry (DPV) technique. Additionally, voltammetric results wer...

A piezoelectric immunosensor based on gold nanoparticles (AuNPs) co-immobilized on a dithiol-modified surface is proposed for detection of human cardiac troponin T (TnT). Anti-human troponin T (anti-TnT) antibodies were covalently immobilized on the nanostructured electrode surface by thiol-aldehyde linkages. In a homogeneous bulk solution, TnT was captured by anti-TnT immobilized on the QCM electrode. Cyclic voltammetry studies were used to characterize the AuNPs layer on the electrode surface and the anti-TnT immobilization steps. The QCM-flow immunosensor exhibited good reliability, measuring concentrations of TnT from 0.003 to 0.5 ng mL −1 in human serum with high linearity (r = 0.989; p < 0.01). The immunosensor exhibited a 7% coefficient of variation and 0.0015 ng mL −1 limit of detection, indicating a high reproducibility and sensitivity. The proposed QCM nanostructured immunosensor is easy to use and has promising potential in the diagnosis of acute myocardial infarction due to its speed and high sensitivity.

With the rise in public health awareness, research on point-of-care testing (POCT) has significantly advanced. Electrochemical biosensors (ECBs) are one of the most promising candidates for the future of POCT due to their quick and accurate response, ease of operation, and cost effectiveness. This review focuses on the use of metal nanoparticles (MNPs) for fabricating ECBs that has a potential to be used for POCT. The field has expanded remarkably from its initial enzymatic and immunosensor-based setups. This review provides a concise categorization of the ECBs to allow for a better understanding of the development process. The influence of structural aspects of MNPs in biocompatibility and effective sensor design has been explored. The advances in MNP-based ECBs for the detection of some of the most prominent cancer biomarkers (carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), Herceptin-2 (HER2), etc.) and small biomolecules (glucose, dopamine, hydrogen peroxide, etc.) ha...

17α-Ethinyl estradiol (EE2), which is used worldwide in the treatment of some cancers and as a contraceptive, is often found in aquatic systems and is considered a pharmaceutically active compound (PhACs) in the environment. Current methods for the determination of this compound, such as chromatography, are expensive and lengthy and require large amounts of toxic organic solvents. In this work, a voltammetric procedure is developed and validated as a screening tool for detecting EE2 in water samples without prior extraction, clean-up, or derivatization steps. Application of the method we elaborate here to EE2 analysis is unprecedented. EE2 detection was carried out using differential pulse adsorptive cathodic stripping voltammetry (DP AdCSV) with a hanging mercury drop electrode (HMDE) in pH 7.0 Britton-Robinson buffer. The electrochemical process of EE2 reduction was investigated by cyclic voltammetry at different scan rates. Electroreduction of the hormone on a mercury electrode e...

Feline herpesvirus 1 (FHV-1) infection causes feline viral rhinotracheitis (FVR) and is one of the most widespread viral infections in cats. It can cause severe disease, including death from pneumonia in young kittens, and it accounts for approximately half of all diagnosed feline viral upper respiratory infections. FVR is usually diagnosed by clinical signs. However, for a definitive diagnosis laboratory techniques such as PCR (polymerase chain reaction) or virus isolation are required; diagnostic methods that are relatively expensive or require well-trained personnel. Therefore, the development of a biosensing method that can deliver concrete, same-day results in a simple and inexpensive manner can elevate the prompt response to infection cases.

In this work, the synthesis, characterization, and application of novel parabens imprinted polymers as highly selective solid-phase extraction (SPE) sorbents have been reported. The imprinted polymers were created using sol–gel molecular imprinting process. All the seven parabens were considered herein in order to check the phase selectivity. By means of a validated HPLC-photodiode array detector (PDA) method all seven parabens were resolved in a single chromatographic run of 25 min. These SPE sorbents, in-house packed in SPE empty cartridges, were first characterized in terms of extraction capability, breakthrough volume, retention volume, hold-up volume, number of theoretical plates, and retention factor. Finally, the device was applied to a real urine sample to check the method feasibility on a very complex matrix. The new paraben imprinted SPE sorbents, not yet present in the literature, potentially encourage the development of novel molecularly imprinted polymers (MIPs) to enha...

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.

A novel fluidic-based electrochemical ELISA platform is descried for estimation of the bladder cancer protein markers nuclear mitotic apparatus protein 1 (NUMA1) and complement factor H-related 1 (CFHR1). The platform uses an off-site chamber for a sandwich immunoassay and performs the electrochemistry on-chip in a separate chamber. The off-site matrices were connected to the sensor chip in a manner that the sensors were exposed only to the final electroactive product for signal detection, thus avoiding interference from other molecules present in the sample. Two off-site matrices using 3D polymethyl methacrylate (PMMA) sheets and 2D polycarbonate (PC) membranes modified with the desired antibodies were investigated. Antibodies for NUMA1 and CFHR1 were utilized for the immunoassay and hair comb structured gold electrodes were used for sensing. Results in 10% synthetic urine reveal that the system can detect NUMA1 and CFHR1 in the 1-100 ng/ml range with high sensitivities of 260 nA/(ng/ml) and 310 nA/(ng/ml), for NUMA1 and CFHR1, respectively; negligible interference from the diluted urine and other molecules has been observed. A fully automated fluidic prototype has also been developed to demonstrate that automation of the process and multiplexing of detection can be achieved in a small footprint benchtop device. The use of off-site matrix-based platforms paves the way towards a new generation of electrochemical immunosensors for biomarker estimation with negligible non-specific interactions and false signals in complex samples.

The SARS-CoV-2 virus is still causing a dramatic loss of human lives worldwide, constituting an unprecedented challenge for the society, public health and economy, to overcome. The up-to-date diagnostic tests, PCR, antibody ELISA and Rapid Antigen, require special equipment, hours of analysis and special staff. For this reason, many research groups have focused recently on the design and development of electrochemical biosensors for the SARS-CoV-2 detection, indicating that they can play a significant role in controlling COVID disease. In this review we thoroughly discuss the transducer electrode nanomaterials investigated in order to improve the sensitivity, specificity and response time of the as-developed SARS-CoV-2 electrochemical biosensors. Particularly, we mainly focus on the results appeard on Au-based and carbon or graphene-based electrodes, which are the main material groups recently investigated worldwidely. Additionally, the adopted electrochemical detection techniques are also discussed, highlighting their pros and cos. The nanomaterial-based electrochemical biosensors could enable a fast, accurate and without special cost, virus detection. However, further research is required in terms of new nanomaterials and synthesis strategies in order the SARS-CoV-2 electrochemical biosensors to be commercialized.

especiación de cromo ……………………..……………………………… 2.3. Bibliografía ……………………………………………………………………………….... 3. BIOSENSOR ELECTROQUÍMICO BASADO EN EL ENZIMA PAO PARA LA DETERMINACIÓN DE TIRAMINA ……………………………………………………………… 3.1. Introducción ………………………………………………………………………………… 3.2. Disposable amperometric biosensor for the determination of tyramine using plasma amine oxidase ………………………………..…… 4. BIOSENSOR ELECTROQUÍMICO BASADO EN EL ENZIMA HRP PARA LA DETERMINACIÓN DE TIRAMINA ……………………………….……………………………..

Foodborne safety has aroused tremendous research interest in recent years because of a global public health problem. The rapid and precise detection of foodborne pathogens can reduce significantly infection diseases and save lives by the early initiation of an effective treatment. This review highlights current advances in the development of biosensors for detection of Campylobacter spp. and Listeria monocytogenes that are the most common causes of zoonosis. The consumption of pathogen contaminated food is responsible for humans hospitalization and death. The attention focused on the recognition elements such as antibodies (Ab), DNA probes and aptamers able to recognize cells, amplicons, and specific genes from different samples like bacteria, food, environment and clinical samples. Moreover, the review focused on two main signal-transducing mechanisms, i.e., electrochemical, measuring an amperometric, potentiometric and impedimetric signal; and optical, measuring a light signal by ...

The excessive use of antibiotics in human and veterinary medicine causes the emergence of multidrug resistant bacteria. In this context, the surveillance of many different antibiotics provokes a worldwide challenge. Hence, fast and versatile multianalyte single-use biosensors are of increasing interest for many fields such as medical analysis or environmental and food control. Here we present a microfluidic platform enabling the electrochemical readout of up to eight enzyme-linked assays (ELAs), simultaneously. To demonstrate the applicability of this platform for the surveillance and monitoring of antibiotics, we used highly sensitive biomolecular sensor systems for the simultaneous detection of two commonly employed antibiotic classes tetracycline and streptogramin. Thus, microfluidic channel networks are designed, comprising distinct numbers of immobilization sections with a very low volume of 680 nL each. These passively metered sections can be actuated separately for an individ...

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer accounting for 85% of all newly diagnosed cases. Its prognosis remains poor as most patients are diagnosed at an advanced stage. In this study, we report the development of an electrochemical immunosensor for quantitative detection of Yamaguchi sarcoma viral oncogene homolog 1 (v-YES1) protein, comprised of a glassy carbon electrode modified with gold nanoparticles (AuNP), thiolated protein G (TPG), YES1 antibody (AB1) and glutaraldehyde (GA), which was used as a cross linker. Cyclic voltammetry (CV) and Differential pulse voltammetry (DPV) were used to measure the response and characterization of the fabricated immunosensor. The fabricated immunosensor, glassy carbon electrode (GCE)/AuNP/TPG/GA/Ab1) was optimized for pH, response time, antibody concentration and temperature. Under optimum conditions, the immunosensor displayed high sensitivity, recording a limit of detection (LOD) of 0.0014 ng/mL and was noted to have negligible cross reactivity. The proposed immunosensor proved to be stable for up to 2 weeks, which means that it can be used as an alternative diagnostic tool for the rapid, sensitive and specific detection of YES1 antigen in clinical samples for clinical monitoring of cancer progression.

ABSTRACTPresent work displays the preparation of an electrochemical biosensor using a conjugated polymer and laccase enzyme for catechol quantification in samples. The biosensing system is based on an enzyme immobilization on polymer modified graphite transducer surface. For that purpose, a random conjugated polymer, thienothiophene‐benzoxadiazole‐alt‐benzodithiophene (BOTT), was coated onto a graphite electrode surface via drop casting method followed by immobilization of a biomolecule (laccase) for sensing experiments. Herein, for the first time, we proposed a BOTT polymer as an inexpensive and effective way to fabricate highly sensitive and fast response biosensors. The proposed sensing system possessed superior properties with 0.38 μM limit of detection and 110.81 μA mM−1 sensitivity. Furthermore, cyclic voltammetry and scanning electron microscopy techniques were used to examine the surface modifications. The proposed system could be useful for many future studies for catechol ...

The development of a simple and fast cancer detection method is crucial since early diagnosis is a key factor in increasing survival rates for lung cancer patients. Among several diagnosis methods, the electrochemical sensor is the most promising one due to its outstanding performance, portability, real-time analysis, robustness, amenability, and cost-effectiveness. Conducting polymer (CP) composites have been frequently used to fabricate a robust sensor device, owing to their excellent physical and electrochemical properties as well as biocompatibility with nontoxic effects on the biological system. This review brings up a brief overview of the importance of electrochemical biosensors for the early detection of lung cancer, with a detailed discussion on the design and development of CP composite materials for biosensor applications. The review covers the electrochemical sensing of numerous lung cancer markers employing composite electrodes based on the conducting polyterthiophene, poly(3,4-ethylenedioxythiophene), polyaniline, polypyrrole, molecularly imprinted polymers, and others. In addition, a hybrid of the electrochemical biosensors and other techniques was highlighted. The outlook was also briefly discussed for the development of CP composite-based electrochemical biosensors for POC diagnostic devices.

An ultrasensitive electrochemical aptasensor was designed with a bifunctionalized conducting polymer nanobioconjugate to monitor patients' progress in cancer immunotherapy by detecting IFN-γ. The sensing probe was fabricated by covalently immobilizing aptamer on a polyterthiophene benzoic acid composited with multi-walled carbon nanotube/Au nanoparticles. The nanobioconjugate was prepared through the self-assembly of bifunctionalized terthiophene aminobenzoic acid (TABA) onto AuNPs then covalently attached with a redox indicator and an antibody on the amine and carboxyl groups of TABA, respectively. At the optimized condition, the sensor detected IFN-γ in the concentration range of 0.5 fM-100 pM with a detection limit of 0.46 ± 0.006 fM (RSD ≤5.1%). The sensor was applied to monitor the extracellular release of IFN-γ by peripheral blood mononuclear cells and the IFN-γ levels in patients' serum before and after immunotherapy. We observed a low concentration of 0.07 ± 0.004 pM (RSD ≤5.6%) before therapy, which increased significantly to 0.43 ± 0.02 pM (RSD ≤5.1%) after immunotherapy. Meanwhile, a high IFN-γ level of 0.67 ± 0.04 pM (RSD ≤6.2%) was detected in healthy controls. In addition, our study showed IFN-γ is a more effective biomarker for predicting patients' response to blockade therapy as compared to granzyme B.

A novel electrochemical sensor based on molecularly imprinted polymer (MIP) with sensitive and selective binding sites for minoxidil (MX) were developed. The MIP film was cast on the glassy carbon electrode by electrochemical polymerization in a solution containing ternary monomers and MX as a template via cyclic voltammetry scans. The coated polymer was further modified by Ag nanoparticles (NPs). The selection of the suitable functional monomer(s) was based on the interaction between different monomers and template using the density functional theory (DFT). The resulted modified electrode was characterized by cyclic voltammetry (CV), scanning electron microscopic (SEM) and electrochemical impedance spectroscopy (EIS). Under the optimum conditions, the oxidation peak current was proportional to MX concentration over the range of 0.03-500 µM. The detection limit (LOD) was found to be 0.01µM. This sensor was successfully applied for the determination of MX in real samples.

With the rise in public health awareness, research on point-of-care testing (POCT) has significantly advanced. Electrochemical biosensors (ECBs) are one of the most promising candidates for the future of POCT due to their quick and accurate response, ease of operation, and cost effectiveness. This review focuses on the use of metal nanoparticles (MNPs) for fabricating ECBs that has a potential to be used for POCT. The field has expanded remarkably from its initial enzymatic and immunosensor-based setups. This review provides a concise categorization of the ECBs to allow for a better understanding of the development process. The influence of structural aspects of MNPs in biocompatibility and effective sensor design has been explored. The advances in MNP-based ECBs for the detection of some of the most prominent cancer biomarkers (carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), Herceptin-2 (HER2), etc.) and small biomolecules (glucose, dopamine, hydrogen peroxide, etc.) ha...

The central nervous system relies heavily on neurotransmitters (NTMs), and NTM imbalances have been linked to a wide range of neurological conditions. Thus, the development of reliable detection techniques is essential for advancing brain studies. This review offers a comprehensive analysis of metal-organic frameworks (MOFs), transition metal oxides (TMOs), and MOFs-derived TMOs (MOFs/TMOs) as materials for electrochemical (EC) sensors targeting the detection of key NTMs, specifically dopamine (DA), epinephrine (EP), and serotonin (SR). The unique properties and diverse families of MOFs and TMOs, along with their nanostructured hybrids, are discussed in the context of EC sensing. The review also addresses the challenges in detecting NTMs and proposes a systematic approach to tackle these obstacles. Despite the vast amount of research on MOFs and TMOs-based EC sensors for DA detection, the review highlights the gaps in the literature for MOFs/TMOs-based EC sensors specifically for EP and SR detection, as well as the limited research on microneedles (MNs)-based EC sensors modified with MOFs, TMOs, and MOFs/TMOs for NTMs detection. This review serves as a foundation to encourage researchers to further explore the potential applications of MOFs, TMOs, and MOFs/TMOs-based EC sensors in the context of neurological disorders and other health conditions related to NTMs imbalances.

The aim of this study was to develop a simple, reliable voltammetric method and its validation for determination of nonsteroidal antiinflammatory drug diclofenac (DFC). Methods: The proposed method was based on electro-oxidation of DFC at poly (erichrome black T) modified glassy carbon electrode (PEBT/GCE) in 0.2 M phosphate buffer solution of pH 7.0. Cyclic voltammetry and differential pulse voltammetric techniques were employed to study electrooxidation behavior. Under the optimal conditions, variations of EBT concentration, effect of pH, scan rate on the oxidation of DFC was studied. Results: A well-defined oxidation peak at about +0.59 V vs. standard calomel electrode was observed for voltammetric detection of DFC. pH effect shows the participation of an equal number of protons and electrons in the mechanism. The relation between a logarithm of peak current with the logarithm of scan rate indicated adsorption controlled behavior of electrode process. Concentration variations show a good linear response in the range 0.05 µM to 40 µM with the detection limit of 5.25 × 10-8 M. Conclusion: The prepared sensor exhibited good selectivity, sensitivity, and stability for the detection of DFC in the pharmaceutical dosage form and real samples. The developed method could possibly be adopted for pharmacokinetic studies and also in clinical and quality control laboratories where time and economy were important.

The modification of carbon paste electrode (CPE) with molecularly imprinted polymer (MIP) for the determination of rhodamine-B by potentiometry method has been studied. The experiments were performed using glutamic acid as a monomer. The composition of monomers, the number of electropolymerization cycles and pH of the solution were used to describe modification electrodes made (CPE-MIP's) and the electrode characteristics were evaluated. It was observed the amount of oxidation current signal increase with increasing glutamic acid concentration. The optimal polymerization molar ratio of the functional monomer to the template molecule rhodamine-B was 3:1; the maximum number of electropolymerization was 15 and the optimum pH of supporting electrolyte solution was 4.

This work presents a thorough electrochemical and reliability analysis of a sensing scheme for the antipsychotic clozapine. We have previously demonstrated a novel detection approach for this redox-active drug, highly effective in schizophrenia treatment, based on a catecholmodified chitosan film. The biomaterial film enables amplification of the oxidative current generated by clozapine through redox cycling. Here, we study critical electrochemical and material aspects of the redox cycling system to overcome barriers in point-of-care monitoring in complex biological samples. Specifically, we explore the electrochemical parameter space, showing that enhanced sensing performance depends on the presence of a reducing mediator as well as the electrochemical technique applied. These factors account for up to 1.75-fold and 2.47-fold signal enhancement, respectively. Looking at potential interferents, we illustrate that the redox cycling system allows for differentiation between selected redoxactive species, clozapine's structurally largely analogous metabolite norclozapine as well as the representative catecholamine dopamine. Furthermore, we investigate material stability and fouling with reuse as well as storage. We find no evidence of film fouling due to clozapine; slow overall biomaterial degradation with successive use accounts for a 2.2% absolute signal loss and can be controlled for. Storage of the redox cycling system appears feasible over weeks when kept in solution with only 0.26%/day clozapine signal degradation, while ambient air exposure of three or more days reduces performance by 58%. This study not only advances our understanding of the catechol-modified chitosan system, but also further establishes the viability of applying it toward sensing clozapine in a clinical setting. Such point-of-care monitoring will allow for broader use of clozapine by increasing convenience to patients as well as medical professionals, thus improving the lives of people affected by schizophrenia through personalized medicine.

Schizophrenia is a lifelong mental disorder with few recent advances in treatment. Clozapine is the most effective antipsychotic for schizophrenia treatment. However, it remains underutilized since frequent blood draws are required to monitor adverse side effects, and maintain clozapine concentrations in a therapeutic range. Micro-system technology utilized towards real-time monitoring of efficacy and safety will enable personalized medicine and better use of this medication. Although work has been reported on clozapine detection using its electrochemical oxidation, no in situ monitoring of clozapine has been described. In this work, we present a new concept for clozapine in situ sensing based on amplifying its oxidation current. Specifically, we use a biofabricated catechol-modified chitosan redox cycling system to provide a significant amplification of the generated oxidizing current of clozapine through a continuous cycle of clozapine reduction followed by re-oxidation. The amplified signal has improved the signal-tonoise ratio and provided the required limit-of-detection and dynamic range for clinical applications with minimal pre-treatment procedures. The sensor reports on the functionality and sensitivity of clozapine detection between 0.1 and 10 g/mL. The signal generated by clozapine using the catechol-modified chitosan amplifier has shown to be 3 times greater than the unmodified system. The sensor has the ability to differentiate between clozapine and its metabolite norclozapine, as well as the feasibility to detect clozapine in human serum in situ within the required dynamic range for clinically related applications. This new biosensing approach can be further developed towards its integration in miniaturized devices for improved personalized mental health care.

Bacterial colonization of surfaces and interfaces has a major impact on various areas in-cluding biotechnology, medicine, food industries, and water technologies. In most of these areas biofilm development has a strong impact on hygiene situations, product quality, and process efficacies. In consequence, biofilm manipulation and prevention is a fundamental issue to avoid adverse impacts. For such scenario online, non-destructive biofilm monitor-ing systems become important in many technical and industrial applications. This study re-ports such a system in form of a microfluidic sensor platform based on the combination of electrical impedance spectroscopy and amperometric current measurement, which allows sensitive online measurement of biofilm formation and activity. A total number of 12 parallel fluidic channels enable real-time online screening of various biofilms formed by different Pseudomonas aeruginosa and Stenotrophomonas maltophilia strains and complex mixed population biofi...

The synthesis of a new heterobinuclear cobaloxime with 4-(2-ferrocenylvinyl)pyridine, fcvpy, is reported. The complex [CoCl(dmgH)2(fcvpy)], where dmgH2is dimethylglyoxime and dmgH is dimethylglyoximato, has been characterized by1H-NMR, UV-Vis, cyclic voltammetry, and elemental analysis. The cyclic voltammogram of this complex shows a fc/fc+reversible wave at +0.58 V versus Ag/AgCl, one irreversible wave,Epc= −0.54 V versus Ag/AgCl, assigned to the reduction of Co(III) to Co(II), and two quasireversible processes at −1.02 V and −1.10 V versus Ag/AgCl associated with the reduction of Co(II). The complex showed ferrocene-ligand charge transfer bands at 334 nm and 505 nm. TDDFT/B3LYP/6-31G(d) calculations support this assignation.

The immobilization procedure is one of the key factors affecting the electron transfer based biosensors performance. It must assure both the enzyme retention activity and an efficient communication between the redox center of the enzyme and the electrode surface. In this regard, hydrogels are attractive materials due to their three-dimensional hydrophilic networks and their high-water concentration, promoting the biomolecule longterm stability and providing a suitable scaffold for trapping. To this aim, we have synthesized a gelling tripeptide Fluorenylmethyloxycarbonyl-triphenylalanine (FmocPhe 3) produced starting from Fmoc-phenylalanine and diphenylalanine by the catalytic activity of Lipase in water and characterized its performance as a new immobilization support for biosensors. For this purpose, we have evaluated the main bioelectrochemical properties of Trametes versicolor Laccase (TvL) immobilized within the hydrogel and a hydrogel-nanocomposite structure in the presence of gold nanoparticles (AuNPs). Either the Fmoc and the benzyl rings inside the tripeptide structure contributed to the hydrogel network formation by π-π stacking interactions, which promoted the physical entrapment of Laccase as well as the interaction with the carbon-based electrode surface. Furthermore, the π-electrons flow throughout the tripeptide based hydrogel allowed a good electron transfer between the immobilized enzyme and the electrode. The obtained results showed a significative increase in the hydrogel nanocompositebased graphite biosensor performance with respect to those obtained with the hydrogel-based graphite biosensor. The experimental results, in terms of analytical performance and costs, assessed the possible use of FmocPhe 3 based hydrogels in the development of electrochemical biosensors.

An automatic system for the determination of Zn, Cd, Pb and Cu by anodic stripping potentiometry using the oxygen dissolved in the sample as oxidant is reported. The system relies on the use of a PC-compatible computer for instrumental control and data acquisition and processing.

A microbial biosensor based on Gluconobacter oxydans cells immobilized on the conducting polymer of 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)benzenamine (SNS-NH 2) coated onto the surface of graphite electrode was constructed. The proposed biosensor was characterized using glucose as the substrate. The linear relation was observed in the range of 0.1-2.5 mM and defined by the equation y = 0.415x + 0.377 (R 2 = 0.986). Analytical characterization, effects of electropolymerization time, pH, cell amount and the presence of gold nanoparticles (GNP) on the polymer surface together with the biological material were examined as well. Finally, the system was used for ethanol and glucose detection in real samples.

A piezoelectric immunosensor based on gold nanoparticles (AuNPs) co-immobilized on a dithiol-modified surface is proposed for detection of human cardiac troponin T (TnT). Anti-human troponin T (anti-TnT) antibodies were covalently immobilized on the nanostructured electrode surface by thiol-aldehyde linkages. In a homogeneous bulk solution, TnT was captured by anti-TnT immobilized on the QCM electrode. Cyclic voltammetry studies were used to characterize the AuNPs layer on the electrode surface and the anti-TnT immobilization steps. The QCM-flow immunosensor exhibited good reliability, measuring concentrations of TnT from 0.003 to 0.5 ng mL −1 in human serum with high linearity (r = 0.989; p < 0.01). The immunosensor exhibited a 7% coefficient of variation and 0.0015 ng mL −1 limit of detection, indicating a high reproducibility and sensitivity. The proposed QCM nanostructured immunosensor is easy to use and has promising potential in the diagnosis of acute myocardial infarction due to its speed and high sensitivity.

Institute of Technology Rourkela for firstly the opportunity to undertake this project and secondly for their guidance, patience and support throughout my study. They have always pointed me in the right direction with their experience and their contributions to this research are greatly appreciated. He has consistently pushed me to deliver my best, and I am very grateful to him for supervising me throughout the year. I am grateful to the research team of the Biotransport and Biomechanics laboratory here at National institute of technology, Rourkela for giving me an unforgettable experience during my postgraduate studies. There are too many of them to fit this small area, but each and every one of them is remembered for contributing, in one way or another, to the success of this work. I would like to specially thank to my fellow research workers and friends Krishna Reddy, Nakul Dewan and Protima a big thank you for without your humour, listening ears and assistance over a year I doubt this project would hold as special a place in my life. Thank you to my family who always support me no matter what course I embark, so you all become extra special supporters of this work. Lastly, I thank Almighty God with whose blessings I have reached at the completion of my research.