A critical review on the use of potentiometric based biosensors for biomarkers detection

Electrochemically Active Materials for Tissue-Interfaced Soft Biochemical Sensing

Tissue-interfaced soft biochemical sensing represents a crucial approach to personalized healthcare by employing electrochemically active materials to monitor biochemical signals at the tissue interface in real time, either noninvasively or through implantation. These soft biochemical sensors can be integrated with various biological tissues, such as neural, gastrointestinal, ocular, cardiac, skin, muscle, and bone, adapting to their unique mechanical and biochemical environments. Sensors employing materials like conductive polymers, composites, metals, metal oxides, and carbon-based nanomaterials have demonstrated capabilities in applications, such as continuous glucose monitoring, neural activity mapping, and real-time metabolite detection, enhancing diagnostics and treatment monitoring across a range of medical fields. Next-generation tissue-interfaced biosensors that enable multimodal and multiplexed measurement of biochemical markers and physiological parameters could be transformative for personalized medicine, allowing for high-resolution, time-resolved historical monitoring of an individual's health status. In this review, we summarize current trends in the field to provide insights into the challenges and future trajectory of tissue-interfaced soft biochemical sensors, highlighting their potential to revolutionize personalized medicine and improve patient outcomes.

A novel GLUT-4 electrochemical immunosensor based on a poly(thionine)-gold nanoparticle nanocomposite: Combining complex capacitance and dissolved oxygen to obtain an analytical signal

Detection of glucose transporter 4 (GLUT4) is essential for understanding various physiological and pathological processes. This work reports the development of a novel electrochemical immunosensor for the direct detection of GLUT4, employing dissolved oxygen as a redox probe. This molecular oxygen-sensitive response is mediated by a redox-conductive polymer based on thionine. The sensor platform was fabricated via a one-step electropolymerization of thionine and gold nanoparticles (AuNPs) onto a platinum screen-printed electrode (Olean-Oliveira et al., 2022a). The immunosensor was then constructed by physical adsorption of a GLUT4 antibody onto the poly(thionine)-AuNP composite surface. This label-free approach eliminates the need for secondary antibodies or enzymes. The immunosensor performance was evaluated using electrochemical impedance spectroscopy (EIS). The sensing mechanism relies on impedance changes; increasing GLUT4 concentrations lead to increased impedance due to enhanced surface blocking upon GLUT4-antibody binding. This interaction impedes oxygen diffusion to the polymer redox sites, resulting in increased electrical resistance. Analysis of the redox capacitance as a function of frequency demonstrates a decrease in the capacitive arc with increasing GLUT4 concentration.

Ion-Selective Electrodes: Selectivity Coefficients for Interfering Ions of the Opposite Charge Sign

The way upper limits of detection (LODs) are typically reported in the ion-selective electrode (ISE) literature is unfortunately outdated. It is well understood that the upper LOD of a polymeric-membrane ISE is limited by Donnan failure, that is, the transfer of primary ions along with interfering ions of the opposite charge sign (commonly referred to as counterions) from the sample into the sensing membrane. However, it is often difficult to compare upper LODs for ISEs from different sources. The majority of publications on ISEs describe Donnan failure for one type of counterion only, making it impossible for end users to predict the interference for other counterions. Moreover, linear ranges for ISEs based on different ionophores cannot be compared to one another when Donnan failure was reported for different counterions. To this end, we introduce here selectivity coefficients, KI,XpotX, for interfering counterions. Using this new concept, the primary ion activity at which Donnan failure occurs can be readily predicted from measured KI,XpotX values by the use of the uncomplicated expression aXzI/zx/KI,XpotX. Consistent with the intuition that many ISE users have for conventional selectivity coefficients, large KI,XpotX values are characteristic for counterions that interfere strongly. We show experimentally that trends as predicted by the phase boundary model for Donnan failure, such as the effects of counterion hydrophobicity and ionophore complex stability, are often accurately predicted with the KI,XpotX approach. However, there are notable exceptions when the underlying assumptions made by users do not apply, such as when counterions unexpectedly form aggregates with other species in the sensing membranes. The empirically measured KI,XpotX coefficients enable the discovery of such phenomena, opening a rational path to improving upper LODs and, thereby, linear response ranges.

Biosensors, Artificial Intelligence Biosensors, False Results and Novel Future Perspectives

Medical biosensors have set the basis of medical diagnostics, and Artificial Intelligence (AI) has boosted diagnostics to a great extent. However, false results are evident in every method, so it is crucial to identify the reasons behind a possible false result in order to control its occurrence. This is the first critical state-of-the-art review article to discuss all the commonly used biosensor types and the reasons that can give rise to potential false results. Furthermore, AI is discussed in parallel with biosensors and their misdiagnoses, and again some reasons for possible false results are discussed. Finally, an expert opinion with further future perspectives is presented based on general expert insights, in order for some false diagnostic results of biosensors and AI biosensors to be surpassed.

Tetrahedral DNA nanostructures-assisted electrochemical assay for detecting circulating tumor DNA by combining a masking tactic with 3D-hybridization chain reactions

Circulating tumor DNA (ctDNA) is a remarkable noninvasive tumor marker that plays a crucial role in tumor diagnosis, prognosis and treatment. However, detecting low-abundance ctDNA from a substantial amount of nucleic acids originating from healthy cells is challenging. Herein, we proposed a tetrahedral DNA nanostructures (TDNs)-assisted electrochemical biosensor for ctDNA detection. This biosensor combines a masking tactic with 3D-hybridization chain reactions. Masking hairpins (MHs) were initially introduced to prevent interference from wild-type (WT) DNA. Then, the initiator sequence was transferred to the electrode surface modified with TDNs by the target ctDNA. The initiator sequence triggers the 3D self-assembly of hairpin strands, leading to the formation of DNA networks or even DNA hydrogels (long reaction time). This process generates numerous evenly distributed biotin molecules that can bind to streptavidin peroxidase to considerably amplify the signal. This method exhibits high sensitivity (the minimum concentration for detecting ctDNA is 1 aM, which corresponds to 60 ctDNA molecules in 100 μl sample) and excellent specificity (single mismatch). More importantly, this high-performance sensor can detect ctDNA with other mutation sites and their mixtures by modifying the corresponding capture probes on the TDNs. Furthermore, this ultrasensitive sensor effectively detects target ctDNA (0.001 %) at high levels of WT DNA and in complex matrices such as serum. These findings suggest that the sensor has promising potential as a noninvasive tool for early tumor diagnosis.

Biosensor Technologies for Water Quality: Detection of Emerging Contaminants and Pathogens

This review explores the development, technological foundations, and applications of biosensor technologies across various fields, such as medicine for disease diagnosis and monitoring, and the food industry. However, the primary focus is on their use in detecting contaminants and pathogens, as well as in environmental monitoring for water quality assessment. The review classifies different types of biosensors based on their bioreceptor and transducer, highlighting how they are specifically designed for the detection of emerging contaminants (ECs) and pathogens in water. Key innovations in this technology are critically examined, including advanced techniques such as systematic evolution of ligands by exponential enrichment (SELEX), molecularly imprinted polymers (MIPs), and self-assembled monolayers (SAMs), which enable the fabrication of sensors with improved sensitivity and selectivity. Additionally, the integration of microfluidic systems into biosensors is analyzed, demonstrating significant enhancements in performance and detection speed. Through these advancements, this work emphasizes the fundamental role of biosensors as key tools for safeguarding public health and preserving environmental integrity.

Recent Advances in Electrochemical Biosensors for Neurodegenerative Disease Biomarkers

Neurodegenerative diseases, such as Parkinson's disease (PD) and Alzheimer's disease (AD), represent a growing global health challenge with overlapping biomarkers. Key biomarkers, including α-synucleins, amyloid-β, and Tau proteins, are critical for accurate detection but are often assessed using conventional methods like enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR), which are invasive, costly, and time-intensive. Electrochemical biosensors have emerged as promising tools for biomarker detection due to their high sensitivity, rapid response, and potential for miniaturization. The integration of nanomaterials has further enhanced their performance, improving sensitivity, specificity, and practical application. To this end, this review provides a comprehensive overview of recent advances in electrochemical biosensors for detecting neurodegenerative disease biomarkers, highlighting their strengths, limitations, and future opportunities. By addressing the challenges of early diagnosis, this work aims to stimulate interdisciplinary innovation and improve clinical outcomes for neurodegenerative disease patients.

Emerging Combination of Hydrogel and Electrochemical Biosensors

Electrochemical sensors are among the most promising technologies for biomarker research, with outstanding sensitivity, selectivity, and rapid response capabilities that make them important in medical diagnostics and prognosis. Recently, hydrogels have gained attention in the domain of electrochemical biosensors because of their superior biocompatibility, excellent adhesion, and ability to form conformal contact with diverse surfaces. These features provide distinct advantages, particularly in the advancement of wearable biosensors. This review examines the contemporary utilization of hydrogels in electrochemical sensing, explores strategies for optimization and prospective development trajectories, and highlights their distinctive advantages. The objective is to provide an exhaustive overview of the foundational principles of electrochemical sensing systems, analyze the compatibility of hydrogel properties with electrochemical methodologies, and propose potential healthcare applications to further illustrate their applicability. Despite significant advances in the development of hydrogel-based electrochemical biosensors, challenges persist, such as improving material fatigue resistance, interfacial adhesion, and maintaining balanced water content across various environments. Overall, hydrogels have immense potential in flexible biosensors and provide exciting opportunities. However, resolving the current obstacles will necessitate additional research and development efforts.

An Interdisciplinary Overview on Ambient Assisted Living Systems for Health Monitoring at Home: Trade-Offs and Challenges

The integration of IoT and Ambient Assisted Living (AAL) enables discreet real-time health monitoring in home environments, offering significant potential for personalized and preventative care. However, challenges persist in balancing privacy, cost, usability, and system reliability. This paper provides an overview of recent advancements in sensor and IoT technologies for assisted living, with a focus on elderly individuals living independently. It categorizes sensor types and technologies that enhance healthcare delivery and explores an interdisciplinary framework encompassing sensing, communication, and decision-making systems. Through this analysis, this paper highlights current applications, identifies emerging challenges, and pinpoints critical areas for future research. This paper aims to inform ongoing discourse and advocate for interdisciplinary approaches in system design to address existing trade-offs and optimize performance.

Electrochemical and optical biosensors for the detection of E. Coli

E. coli is a common pathogenic microorganism responsible for numerous food and waterborne illnesses. Traditional detection methods often require long, multi-step processes and specialized equipment. Electrochemical and optical biosensors offer promising alternatives due to their high sensitivity, selectivity, and real-time monitoring capabilities. Recent advancements in sensor development focus on various techniques for detecting E. coli, including optical (fluorescence, colorimetric analysis, surface-enhanced Raman spectroscopy, surface plasmon resonance, localized surface plasmon resonance, chemiluminescence) and electrochemical (amperometric, voltammetry, impedance, potentiometric). Herein, the latest advancements in optical and electrochemical biosensors created for identifying E. coli with an emphasis on surface modifications employing nanomaterials and biomolecules are outlined in this review. Electrochemical biosensors exploit the unique electrochemical properties of E. coli or its specific biomolecules to generate a measurable signal. In contrast, optical biosensors rely on interactions between E. coli and optical elements to generate a detectable response. Moreover, optical detection has been exploited in portable devices such as smart phones and paper-based sensors. Different types of electrodes, nanoparticles, antibodies, aptamers, and fluorescence-based systems have been employed to enhance the sensitivity and specificity of these biosensors. Integrating nanotechnology and biorecognition (which bind to a specific region of the E. coli) elements has enabled the development of portable and miniaturized devices for on-site and point-of-care (POC) applications. These biosensors have demonstrated high sensitivity and offer low detection limits for E. coli detection. The convergence of electrochemical and optical technologies promises excellent opportunities to revolutionize E. coli detection, improving food safety and public health.

Bioinspired synergy strategy based on the integration of nanozyme into a molecularly imprinted polymer for improved enzyme catalytic mimicry and selective biosensing

Nanozymes offer many advantages such as good stability and high catalytic activity, but their selectivity is lower than that of enzymes. This is because most of enzymes have a protein component (apoenzyme) for substrate affinity to enhance selectivity and a non-protein element (coenzyme) for catalytic activity to improve sensitivity. The synergy between molecularly imprinted polymers (MIPs) and nanozymes can mimic natural enzymes, with MIP acting as the apoenzyme and nanozyme as the coenzyme. Despite researchers' attempts to associate MIPs with nanozymes, the full potential of this combination remains not well explored. This study addresses this gap by integrating Fe3O4-Lys-Cu nanozymes with peroxidase-like catalytic activities within appropriate MIPs for L-DOPA and dopamine. The catalytic performance of the nanozyme was improved by the presence of Cu in Fe3O4-Lys-Cu and further enhanced by MIP. Indeed, the exploration of the pre-concentration property of MIP has increased twenty-fold the catalytic activity of the nanozyme. Moreover, this synergistic combination facilitated the template removal process during MIP production by reducing the extraction time from several hours to just 1 min thanks to the addition of co-substrates which trigger the reaction with nanozyme and release the template. Overall, the synergistic combination of MIPs and nanozymes offers a promising avenue for the design of artificial enzymes.

Detection strategies of infectious diseases via peptide-based electrochemical biosensors

Infectious diseases have threatened human life for as long as humankind has existed. One of the most crucial aspects of fighting against these infections is diagnosis to prevent disease spread. However, traditional diagnostic methods prove insufficient and time-consuming in the face of a pandemic. Therefore, studies focusing on detecting viruses causing these diseases have increased, with a particular emphasis on developing rapid, accurate, specific, user-friendly, and portable electrochemical biosensor systems. Peptides are used integral components in biosensor fabrication for several reasons, including various and adaptable synthesis protocols, long-term stability, and specificity. Here, we discuss peptide-based electrochemical biosensor systems that have been developed over the last decade for the detection of infectious diseases. In contrast to other reports on peptide-based biosensors, we have emphasized the following points i) the synthesis methods of peptides for biosensor applications, ii) biosensor fabrication approaches of peptide-based electrochemical biosensor systems, iii) the comparison of electrochemical biosensors with other peptide-based biosensor systems and the advantages and limitations of electrochemical biosensors, iv) the pros and cons of peptides compared to other biorecognition molecules in the detection of infectious diseases, v) different perspectives for future studies with the shortcomings of the systems developed in the past decade.

Fully integrated microneedle biosensor array for wearable multiplexed fitness biomarkers monitoring

Fitness monitoring has become increasingly important in modern lifestyles; the current fitness monitoring always relies on physical sensors, making it challenging to detect pertinent issues at a deeper level when exercising. Here, we report a fully integrated wearable microneedle sensor that simultaneously measures fitness related biomarkers (e.g., glucose, lactate, and alcohol) during physical exercise. Such a sensor integrates a biocompatible 3D-printed microneedle array that can comfortably access skin interstitial fluid and a small circuit for signal processing and calibration, and wireless communication. The microneedle array features good biocompatibility and highly sensitive biochemical sensors that can detect even the slightest variations within the biomarkers of this fluid. On-body experimental results indicate that such a sensor can monitor fitness-related biomarkers across multiple subjects and support multi-day monitoring, with results showing a good correlation with commercial devices. The data was transmitted to a smartphone via Bluetooth and uploaded to cloud platforms for further health assessment. This study has the potential to boost intelligent wearable devices in sports health.

Label-Free Detection of Waterborne Pathogens Using an All-Solid-State Laser-Induced Graphene Potentiometric Ion Flux Immunosensor

Waterborne pathogens are harmful microorganisms transmitted through water sources. Early and rapid pathogen detection is important for preventing illnesses and implementing stringent water safety measures to minimize the risk of contamination. This work introduces a miniaturized all-solid-state potentiometric ion flux immunosensor for the rapid and label-free detection of waterborne pathogens. A screen-printed silver/silver chloride electrode coated with a reference electrode membrane and polyurethane as an all-solid-state reference electrode was combined with a solid-state contact ion-selective electrode (ISE). An all-solid-state ISE was constructed on laser-induced graphene by coating it with a cationic marker and a carboxylated poly(vinyl chloride)-based membrane for immobilizing antibodies and controlling ion fluxes through the membrane. Proof-of-concept was achieved by detecting Escherichia coli and Salmonella enterica serovar Typhimurium using the assembled immunosensors within 10 min. The potentiometric response shift attributed to the blocking effect in the ion flux caused by pathogen-antibody interaction corresponded to pathogen concentration, indicating detection limits of 0.1 CFU/mL and working ranges of 0.1-105 CFU/mL. Furthermore, the developed sensors revealed high selectivity and were directly applied in groundwater and tap water without any sample preparation, demonstrating high recovery percentages. The simple operation and elimination of sample preparation are key benefits to further usability of the developed immunosensors for efficient pathogen detection.

Sensing with Molecularly Imprinted Membranes on Two-Dimensional Solid-Supported Substrates

Molecularly imprinted membranes (MIMs) have been a focal research interest since 1990, representing a breakthrough in the integration of target molecules into membrane structures for cutting-edge sensing applications. This paper traces the developmental history of MIMs, elucidating the diverse methodologies employed in their preparation and characterization on two-dimensional solid-supported substrates. We then explore the principles and diverse applications of MIMs, particularly in the context of emerging technologies encompassing electrochemistry, surface-enhanced Raman scattering (SERS), surface plasmon resonance (SPR), and the quartz crystal microbalance (QCM). Furthermore, we shed light on the unique features of ion-sensitive field-effect transistor (ISFET) biosensors that rely on MIMs, with the notable advancements and challenges of point-of-care biochemical sensors highlighted. By providing a comprehensive overview of the latest innovations and future trajectories, this paper aims to inspire further exploration and progress in the field of MIM-driven sensing technologies.

Development of cross-linked glucose oxidase integrated Cu-nanoflower electrode for reusable and stable glucose sensing

The demand for glucose-sensing devices has increased along with the increasing diabetic population. Here, we aimed to construct a system with a glucose oxidase (GOx)-integrated Cu-nanoflower (Cu-NF) as the underlying electrode. This novel system was successfully developed by creating a cross-linked GOx within a Cu-NF matrix, forming a c-GOx@Cu-NF-coated film on a carbon screen-printed electrode (CSPE). A comparison of the stabilities of the cross-linking methods demonstrated enhanced durability, with an activity level of >88 % maintained after approximately 35 days of storage in room temperature buffer. Regarding the ability of the c-GOx@Cu-NF modified CSPE to detect glucose via electrochemical methods, the redox potential gap (ΔE) and peak current increased in the presence of GOx. In comparison to that of glucose, the sensitivity of c-GOx@Cu-NF was approximately 8 times greater than that of GOx@Cu-NF, with a detection limit of 0.649 μM and a linear range of 5-500 μM. It sustained an average relative activity of 80 % over 20 days. After 10 cycles of repeated use, the activity remained above 75 %. In terms of evaluating the electrode's specificity for glucose, the detection rate for individual similar substances was approximately 1 %. The introduction of a crosslinking strategy to Cu-NF, leading to enhanced mechanical stability and conductivity, improved the detection capability. Furthermore, this approach led to increased long-term storage stability and reusability, allowing for specific glucose detection. To our knowledge, this report represents the first demonstration of a c-GOx@Cu-NF system for integrating electrochemical biosensing devices into digital healthcare pathways, offering enhanced sensing accuracy and mechanical stability.

Novel Sensor Approaches of Aflatoxins Determination in Food and Beverage Samples

The rapid quantification of toxins in food and beverage products has become a significant issue in overcoming and preventing many life-threatening diseases. Aflatoxin-contaminated food is one of the reasons for primary liver cancer and induces some tumors and cancer types. Advancements in biosensors technology have brought out different analysis methods. Therefore, the sensing performance has been improved for agricultural and beverage industries or food control processes. Nanomaterials are widely used for the enhancement of sensing performance. The enzymes, molecularly imprinted polymers (MIP), antibodies, and aptamers can be used as biorecognition elements. The transducer part of the biosensor can be selected, such as optical, electrochemical, and mass-based. This review explains the classification of major types of aflatoxins, the importance of nanomaterials, electrochemical, optical biosensors, and QCM and their applications for the determination of aflatoxins.

Challenges and Advances in Biomarker Detection for Rapid and Accurate Sepsis Diagnosis: An Electrochemical Approach

Sepsis is a life-threatening condition with high mortality rates due to delayed treatment of patients. The conventional methodology for blood diagnosis takes several hours, which suspends treatment, limits early drug administration, and affects the patient's recovery. Thus, rapid, accurate, bedside (onsite), economical, and reliable sepsis biomarker reading of the clinical sample is an emergent need for patient lifesaving. Electrochemical label-free biosensors are specific and rapid devices that are able to perform analysis at the patient's bedside; thus, they are considered an attractive methodology in a clinical setting. To reveal their full diagnostic potential, electrode architecture strategies of fabrication are highly desirable, particularly those able to preserve specific antibody-antigen attraction, restrict non-specific adsorption, and exhibit high sensitivity with a low detection limit for a target biomarker. The aim of this review is to provide state-of-the-art methodologies allowing the fabrication of ultrasensitive and highly selective electrochemical sensors for sepsis biomarkers. This review focuses on different methods of label-free biomarker sensors and discusses their advantages and disadvantages. Then, it highlights effective ways of avoiding false results and the role of molecular labels and functionalization. Recent literature on electrode materials and antibody grafting strategies is discussed, and the most efficient methodology for overcoming the non-specific attraction issues is listed. Finally, we discuss the existing electrode architecture for specific biomarker readers and promising tactics for achieving quick and low detection limits for sepsis biomarkers.

Graphene Oxide-Poly(vinyl alcohol) Hydrogel-Coated Solid-Contact Ion-Selective Electrodes for Wearable Sweat Potassium Ion Sensing

Solid-contact ion-selective electrodes (SC-ISEs) with ionophore-based polymer-sensitive membranes have been the major devices in wearable sweat sensors toward electrolyte analysis. However, the toxicity of ionophores in ion-selective membranes (ISMs), for example, valinomycin (K+ ion carrier), is a significant challenge, since the ISM directly contacts the skin during the tests. Herein, we report coating a hydrogel of graphene oxide-poly(vinyl alcohol) (GO-PVA) on the ISM to fabricate hydrogel-based SC-ISEs. The hydrogen bond interaction between GO sheets and PVA chains could enhance the mechanical strength through the formation of a cross-linking network. Comprehensive electrochemical tests have demonstrated that hydrogel-coated K+-SC-ISE maintains Nernstian response sensitivity, high selectivity, and anti-interference ability compared with uncoated K+-SC-ISE. A flexible hydrogel-based K+ sensing device was further fabricated with the integration of a solid-contact reference electrode, which has realized the monitoring of sweat K+ in real time. This work highlights the possibility of hydrogel coating for fabricating biocompatible wearable potentiometric sweat electrolyte sensors.

Activated carbon and their nanocomposites derived from vegetable and fruit residues for water treatment

Water pollution remains a pressing environmental issue, with diverse pollutants such as heavy metals, pharmaceuticals, dyes, and aromatic hydrocarbon compounds posing a significant threat to clean water access. Historically, biomass-derived activated carbons (ACs) have served as effective adsorbents for water treatment, owing to their inherent porosity and expansive surface area. Nanocomposites have emerged as a means to enhance the absorption properties of ACs, surpassing conventional AC performance. Biomass-based activated carbon nanocomposites (ACNCs) hold promise due to their high surface area and cost-effectiveness. This review explores recent advancements in biomass-based ACNCs, emphasizing their remarkable adsorption efficiencies and paving the way for future research in developing efficient and affordable ACNCs. Leveraging real-time communication for ACNC applications presents a viable approach to addressing cost concerns.

Extended Review Concerning the Integration of Electrochemical Biosensors into Modern IoT and Wearable Devices

Electrochemical biosensors include a recognition component and an electronic transducer, which detect the body fluids with a high degree of accuracy. More importantly, they generate timely readings of the related physiological parameters, and they are suitable for integration into portable, wearable and implantable devices that are significant relative to point-of-care diagnostics scenarios. As an example, the personal glucose meter fundamentally improves the management of diabetes in the comfort of the patients' homes. This review paper analyzes the principles of electrochemical biosensing and the structural features of electrochemical biosensors relative to the implementation of health monitoring and disease diagnostics strategies. The analysis particularly considers the integration of the biosensors into wearable, portable, and implantable systems. The fundamental aim of this paper is to present and critically evaluate the identified significant developments in the scope of electrochemical biosensing for preventive and customized point-of-care diagnostic devices. The paper also approaches the most important engineering challenges that should be addressed in order to improve the sensing accuracy, and enable multiplexing and one-step processes, which mediate the integration of electrochemical biosensing devices into digital healthcare scenarios.

Recent advances in molecularly imprinted polymer-based electrochemical sensors

Molecularly imprinted polymers (MIPs) are the equivalent of natural antibodies and have been widely used as synthetic receptors for the detection of disease biomarkers. Benefiting from their excellent chemical and physical stability, low-cost, relative ease of production, reusability, and high selectivity, MIP-based electrochemical sensors have attracted great interest in disease diagnosis and demonstrated superiority over other biosensing techniques. Here we compare various types of MIP-based electrochemical sensors with different working principles. We then evaluate the state-of-the-art achievements of the MIP-based electrochemical sensors for the detection of different biomarkers, including nucleic acids, proteins, saccharides, lipids, and other small molecules. The limitations, which prevent its successful translation into practical clinical settings, are outlined together with the potential solutions. At the end, we share our vision of the evolution of MIP-based electrochemical sensors with an outlook on the future of this promising biosensing technology.

Research progress of metal-organic framework nanozymes in bacterial sensing, detection, and treatment

The high efficiency and specificity of enzymes make them play an important role in life activities, but the high cost, low stability and high sensitivity of natural enzymes severely restrict their application. In recent years, nanozymes have become convincing alternatives to natural enzymes, finding utility across diverse domains, including biosensing, antibacterial interventions, cancer treatment, and environmental preservation. Nanozymes are characterized by their remarkable attributes, encompassing high stability, cost-effectiveness and robust catalytic activity. Within the contemporary scientific landscape, metal-organic frameworks (MOFs) have garnered considerable attention, primarily due to their versatile applications, spanning catalysis. Notably, MOFs serve as scaffolds for the development of nanozymes, particularly in the context of bacterial detection and treatment. This paper presents a comprehensive review of recent literature pertaining to MOFs and their pivotal role in bacterial detection and treatment. We explored the limitations and prospects for the development of MOF-based nanozymes as a platform for bacterial detection and therapy, and anticipate their great potential and broader clinical applications in addressing medical challenges.

Advancements in biosensors for cancer detection: revolutionizing diagnostics

Cancer stands as the reigning champion of life-threatening diseases, casting a shadow with the highest global mortality rate. Unleashing the power of early cancer treatment is a vital weapon in the battle for efficient and positive outcomes. Yet, conventional screening procedures wield limitations of exorbitant costs, time-consuming endeavors, and impracticality for repeated testing. Enter bio-marker-based cancer diagnostics, which emerge as a formidable force in the realm of early detection, disease progression assessment, and ultimate cancer therapy. These remarkable devices boast a reputation for their exceptional sensitivity, streamlined setup requirements, and lightning fast response times. In this study, we embark on a captivating exploration of the most recent advancements and enhancements in the field of electrochemical marvels, targeting the detection of numerous cancer biomarkers. With each breakthrough, we inch closer to a future where cancer's grip on humanity weakens, guided by the promise of personalized treatment and improved patient outcomes. Together, we unravel the mysteries that cancer conceals and illuminate a path toward triumph against this daunting adversary. This study celebrates the relentless pursuit of progress, where electrochemical innovations take center stage in the quest for a world free from the clutches of carcinoma.

Nanobiosensors for procalcitonin (PCT) analysis

BACKGROUND

Procalcitonin (PCT) is a critical biomarker that is released in response to bacterial infections and can be used to differentiate the pathogenesis of the infectious process.

OBJECTIVE

In this article, we provide an overview of recent advances in PCT biosensors, highlighting different approaches for biosensor construction, different immobilization methods, advantages and roles of different matrices used, analytical performance, and PCT biosensor construction. Also, we will explain PCT biosensors sensible limits of detection (LOD), linearity, and other analytical characteristics. Future prospects for the development of better PCT biosensor systems are also discussed.

METHODS

Traditional methods such as capillary electrophoresis, high-performance liquid chromatography, and mass spectrometry are effective in analyzing PCT in the medical field, but they are complicated, time-consuming sample preparation, and require expensive equipment and skilled personnel.

RESULTS

In the past decades, PCT biosensors have emerged as simple, fast, and sensitive tools for PCT analysis in various fields, especially medical fields.

CONCLUSION

These biosensors have the potential to accompany or replace traditional analytical methods by simplifying or reducing sample preparation and making field testing easier and faster, while significantly reducing the cost per analysis.

Carbon fiber-based multichannel solid-contact potentiometric ion sensors for real-time sweat electrolyte monitoring

Solid-contact ion-selective electrodes (SC-ISEs) feature miniaturization and integration that have gained extensive attention in non-invasive wearable sweat electrolyte sensors. The state-of-the-art wearable SC-ISEs mainly use polyethylene terephthalate, gold and carbon nanotube fibers as flexible substrates but suffer from uncomfortableness, high cost and biotoxicity. Herein, we report carbon fiber-based SC-ISEs to construct a four-channel wearable potentiometric sensor for sweat electrolytes monitoring (Na+/K+/pH/Cl-). The carbon fibers were extracted from commercial cloth, of which the starting point is addressing the cost and reproducibility issues for flexible SC-ISEs. The bare carbon fiber electrodes exhibited reversible voltammetric and stable impedance performances. Further fabricated SC-ISEs based on corresponding ion-selective membranes disclosed Nernstian sensitivity and anti-interface ability toward both ions and organic species in sweat. Significantly, these carbon fiber-based SC-ISEs revealed high reproducibility of standard potentials between normal and bending states. Finally, a textile-based sensor was integrated with a solid-contact reference electrode, which realized on-body sweat electrolytes analysis. The results displayed high accuracy compared with ex-situ tests by ion chromatography. This work highlights carbon fiber-based multichannel wearable potentiometric ion sensors with low cost, biocompatibility and reproducibility.

Recent Advances in Electrochemical Detection of Cell Energy Metabolism

Cell energy metabolism is a complex and multifaceted process by which some of the most important nutrients, particularly glucose and other sugars, are transformed into energy. This complexity is a result of dynamic interactions between multiple components, including ions, metabolic intermediates, and products that arise from biochemical reactions, such as glycolysis and mitochondrial oxidative phosphorylation (OXPHOS), the two main metabolic pathways that provide adenosine triphosphate (ATP), the main source of chemical energy driving various physiological activities. Impaired cell energy metabolism and perturbations or dysfunctions in associated metabolites are frequently implicated in numerous diseases, such as diabetes, cancer, and neurodegenerative and cardiovascular disorders. As a result, altered metabolites hold value as potential disease biomarkers. Electrochemical biosensors are attractive devices for the early diagnosis of many diseases and disorders based on biomarkers due to their advantages of efficiency, simplicity, low cost, high sensitivity, and high selectivity in the detection of anomalies in cellular energy metabolism, including key metabolites involved in glycolysis and mitochondrial processes, such as glucose, lactate, nicotinamide adenine dinucleotide (NADH), reactive oxygen species (ROS), glutamate, and ATP, both in vivo and in vitro. This paper offers a detailed examination of electrochemical biosensors for the detection of glycolytic and mitochondrial metabolites, along with their many applications in cell chips and wearable sensors.

Self-assembling biomolecules for biosensor applications

Molecular self-assembly has received considerable attention in biomedical fields as a simple and effective method for developing biomolecular nanostructures. Self-assembled nanostructures can exhibit high binding affinity and selectivity by displaying multiple ligands/receptors on their surface. In addition, the use of supramolecular structure change upon binding is an intriguing approach to generate binding signal. Therefore, many self-assembled nanostructure-based biosensors have been developed over the past decades, using various biomolecules (e.g., peptides, DNA, RNA, lipids) and their combinations with non-biological substances. In this review, we provide an overview of recent developments in the design and fabrication of self-assembling biomolecules for biosensing. Furthermore, we discuss representative electrochemical biosensing platforms which convert the biochemical reactions of those biomolecules into electrical signals (e.g., voltage, ampere, potential difference, impedance) to contribute to detect targets. This paper also highlights the successful outcomes of self-assembling biomolecules in biosensor applications and discusses the challenges that this promising technology needs to overcome for more widespread use.

The molecular perspective on the melanoma and genome engineering of T-cells in targeting therapy

Melanoma, an aggressive malignant tumor originating from melanocytes in humans, is on the rise globally, with limited non-surgical treatment options available. Recent advances in understanding the molecular and cellular mechanisms underlying immune escape, tumorigenesis, drug resistance, and cancer metastasis have paved the way for innovative therapeutic strategies. Combination therapy targeting multiple pathways simultaneously has been shown to be promising in treating melanoma, eliciting favorable responses in most melanoma patients. CAR T-cells, engineered to overcome the limitations of human leukocyte antigen (HLA)-dependent tumor cell detection associated with T-cell receptors, offer an alternative approach. By genetically modifying apheresis-collected allogeneic or autologous T-cells to express chimeric antigen receptors, CAR T-cells can appreciate antigens on cell surfaces independently of major histocompatibility complex (MHC), providing a significant cancer cell detection advantage. However, identifying the most effective target antigen is the initial step, as it helps mitigate the risk of toxicity due to "on-target, off-tumor" and establishes a targeted therapeutic strategy. Furthermore, evaluating signaling pathways and critical molecules involved in melanoma pathogenesis remains insufficient. This study emphasizes the novel approaches of CAR T-cell immunoediting and presents new insights into the molecular signaling pathways associated with melanoma.

Light Addressable Potentiometric Sensors for Biochemical Imaging on Microscale: A Review on Optimization of Imaging Speed and Spatial Resolution

Light addressable potentiometric sensors (LAPS) are a competitive tool for unmarked biochemical imaging, especially imaging on microscale. It is essential to optimize the imaging speed and spatial resolution of LAPS since the imaging targets of LAPS, such as cell, microfluidic channel, etc., require LAPS to image at the micrometer level, and a fast enough imaging speed is a prerequisite for the dynamic process involved in biochemical imaging. In this study, we discuss the improvement of LAPS in terms of imaging speed and spatial resolution. The development of LAPS in imaging speed and spatial resolution is demonstrated by the latest applications of biochemistry monitoring and imaging on the microscale.

Selectivity of Electrochemical Reactions Based on Adsorption at Nanoporous Electrodes

Enhancing selectivity is a pivotal area of research when electrodes are utilized as catalysts or sensors. Nanoporous electrodes are representative electrode materials for diverse applications, such as catalysts and sensors. Selectivity arising from nanoporous structures has been applied to systems involving nonfaradaic reactions such as capacitive deionization, electrochemical supercapacitors, and conductometry. Since selectivity in faradaic reactions has primarily been explored based on reactivity and molecular charge and size, we propose that the surface adsorption of reactant molecules can be considered as another crucial factor in achieving selectivity. Our observations reveal that the nonadsorptive reaction of 2-propanol and 2-butanol experienced a more pronounced enhancement compared to the adsorptive reaction of 1-propanol and 1-butanol at nanoporous Pt electrodes, owing to the nanoconfinement effect. Even within the same molecule with a mixture of adsorptive and nonadsorptive reactions, the degree of influence of the nanostructure depends on the adsorptive capacity of the reaction, which affects the overall selectivity. Moreover, the size effect of the reactants in the nanoporous electrode is also dependent on the degree of adsorption. These findings provide valuable insights into the effective utilization of nanoporous materials as catalysts or sensors.

Recent advances in the peptide-based biosensor designs

Biosensors have rapidly emerged as a high-sensitivity and convenient detection method. Among various types of biosensors, optical and electrochemical are the most commonly used. Conventionally, antibodies have been employed to ensure specific interaction between the transmission material and analytes. However, there has been increasing recognition of peptides as a promising recognition element for biosensor development in recent years. The use of peptides as recognition elements provides high level of specificity, sensitivity, and stability for the detection process. The combination of peptide designs and optical or electrochemical detection methods has significantly improved biosensor efficacy. These advancements present opportunities for developing biosensors with diverse functions that can be used to lay a strong scientific foundation for the development of personalized medicine and various other fields. This paper reviews the recent advancements in the development and application of peptide-based optical and electrochemical biosensors, as well as their prospects as a sensor type.

Fabrication of an ultra-sensitive electrochemical DNA biosensor based on CT-DNA/NiFe2O4NPs/Au/CPE for detecting rizatriptan benzoate

A novel and first electrochemical biosensor based on Deoxyribonucleic acid (DNA) as a biological component to measure an antimigraine drug, rizatriptan benzoate (RZB) for patients under treatment in biological samples was developed. A carbon paste electrode (CPE) was modified by calf thymus (CT) double-stranded (ds)-DNA, nickel ferrite magnetic nanoparticles (NiFe2O4NPs), and gold nanoparticles (AuNPs). The morphology of the CT-DNA/NiFe2O4NPs/AuNPs/CPE was characterized by Field emission scanning electron microscope (FESEM). The presence of NiFe2O4NPs and AuNPs was confirmed by energy-dispersive X-ray spectroscopy (EDS) image of the NiFe2O4NPs/AuNPs/CPE surface. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were used to determine the structure and electrochemical characteristics of the CT-DNA/NiFe2O4NPs/AuNPs/CPE. Differential pulse voltammetry (DPV) was used to investigate the electrochemical behavior of RZB. Chronoamperometry (CA) was applied to study the effect of CT-DNA immobilization time on the peak oxidation current of RZB accumulated on the surface of the CT-DNA/NiFe2O4NPs/AuNPs/CPE. The results showed that, under optimum conditions, the prepared electrode responded linearly to RZB concentrations between 0.01 and 2.0 μM, with a 0.0033 μM detection limit (LOD) and 0.01 μM limit of quantification (LOQ). The parameters influencing the biosensor performance (temperature, CT-DNA immobilization time, and RZB/CT-DNA accumulation time) were optimized. DPV showed the displacement of the peak potential towards positive values and the reduction of its current, indicating that the drug could intercalate between the guanine base pairs of CT-DNA. Our biosensor was successfully applied for RZB measurement in human urine, blood serum, plasma samples, and tablets. The presented biosensor was fast response, sensitive, selective, cost-effective, and easy-to-use for RZB determination in pharmaceutical formulations and biological samples.

Panorama of biogenic nano-fertilizers: A road to sustainable agriculture

The ever-increasing demand for food from the growing population has augmented the consumption of fertilizers in global agricultural practices. However, the excessive usage of chemical fertilizers with poor efficacy is drastically deteriorating ecosystem health through the degradation of soil fertility by diminishing soil microflora, environment contamination, and human health by inducing chemical remnants to the food chain. These challenges have been addressed by the integration of nanotechnological and biotechnological approaches resulting in nano-enabled biogenic fertilizers (NBF), which have revolutionized agriculture sector and food production. This review critically details the state-of-the-art NBF production, types, and mechanism involved in cultivating crop productivity/quality with insights into genetic, physiological, morphological, microbiological, and physiochemical attributes. Besides, it explores the associated challenges and future routes to promote the adoption of NBF for intelligent and sustainable agriculture. Furthermore, diverse applications of nanotechnology in precision agriculture including plant biosensors and its impact on agribusiness and environmental management are discussed.

A review of zeolitic imidazolate frameworks (ZIFs) as electrochemical sensors for important small biomolecules in human body fluids

Small biomolecules play a critical role in the fundamental processes that sustain life and are essential for the proper functioning of the human body. The detection of small biomolecules has garnered significant interest in various fields, including disease diagnosis and medicine. Electrochemical techniques are commonly employed in the detection of critical biomolecules through the principle of redox reactions. It is also a very convenient, cheap, simple, fast, and accurate measurement method in analytical chemistry. Zeolitic imidazolate frameworks (ZIFs) are a unique type of metal-organic framework (MOF) composed of porous crystals with extended three-dimensional structures. These frameworks are made up of metal ions and imidazolate linkers, which form a highly porous and stable structure. In addition to their many advantages in other applications, ZIFs have emerged as promising candidates for electrochemical sensors. Their large surface area, pore diameter, and stability make them ideal for use in sensing applications, particularly in the detection of small molecules and ions. This review summarizes the critical role of small biomolecules in the human body, the standard features of electrochemical analysis, and the utilization of various types of ZIF materials (including carbon composites, metal-based composites, ZIF polymer materials, and ZIF-derived materials) for the detection of important small biomolecules in human body fluids. Lastly, we provide an overview of the current status, challenges, and future outlook for research on ZIF materials.

A new sandwich-type electrochemiluminescence sensor based on HPSNs-NH2@Au NPs and AuPdPt NPs for determination of α(2,3)-sial-Gs

A novel sandwich-type "on-off" electrochemiluminescence (ECL) biosensor for the determination of α(2,3)-sial-Gs was designed. Specifically, amino-functionalized porous silica nanoparticles (HPSNs-NH2) were first prepared and then decorated with gold nanoparticles (Au NPs) to form HPSNs-NH2@Au NP nanocomposite, which exhibited a strong ability to enhance ECL intensity with K2S2O8 as co-reactant (signal-on) and could immobilize the target-specific binding molecules of maackia amurensis lectin (MAL). Additionally, AuPdPt trimetallic nanoparticles were prepared to serve as a quenched ECL signal indicator (signal-off) with the ability of capturing the target non-specific binding molecules of 3-aminophenylboronic acid (APBA) to form a signal label. The sandwich-type ECL biosensor was constructed based on the structure of MAL-α(2,3)-sial-Gs-APBA and achieved a determination toward α(2,3)-sial-Gs with a wide linear range from 1 fg mL-1 to 10 ng mL-1 and a low detection limit of 0.5 fg mL-1. Furthermore, the proposed ECL biosensor showed satisfactory selectivity, stability, and reproducibility for α(2,3)-sial-Gs determination.

Nanosensors in the detection of antihypertension drugs, a golden step for medication adherence monitoring

Hypertension is associated with structural and functional changes in blood vessels with increased arteriosclerosis, vascular inflammation, and endothelial dysfunction. Decreased adherence (compliance) to antihypertensive medications contributes significantly to morbidity and mortality in hypertensive patients. Antihypertensive drugs (AHTDs) and lifestyle changes are the main cornerstones for treating hypertension. Several approaches have been described in the literature for determining AHTDs based on different analytical techniques. Amongst biosensors are one of the most attractive tools due to their inherent advantages. Biosensors are used for the detection of wide range of biomarkers as well as different drugs in past two decades. The main focus of the present study is to review the latest biosensors developed for the detection of AHTDs. Readers of the present study will be able to familiarize themselves with biosensors as advanced and modern diagnostic tools while reviewing the most widely used AHTDs. In the present study, the routine methods are first reviewed and while examining their advantages and disadvantages, biosensors have been introduced as ideal alternative tools.

Imprinted Hydrogel Nanoparticles for Protein Biosensing: A Review

Over the past decade, molecular imprinting (MI) technology has made tremendous progress, and the advancements in nanotechnology have been the major driving force behind the improvement of MI technology. The preparation of nanoscale imprinted materials, i.e., molecularly imprinted polymer nanoparticles (MIP NPs, also commonly called nanoMIPs), opened new horizons in terms of practical applications, including in the field of sensors. Currently, hydrogels are very promising for applications in bioanalytical assays and sensors due to their high biocompatibility and possibility to tune chemical composition, size (microgels, nanogels, etc.), and format (nanostructures, MIP film, fibers, etc.) to prepare optimized analyte-responsive imprinted materials. This review aims to highlight the recent progress on the use of hydrogel MIP NPs for biosensing purposes over the past decade, mainly focusing on their incorporation on sensing devices for detection of a fundamental class of biomolecules, the peptides and proteins. The review begins by directing its focus on the ability of MIPs to replace biological antibodies in (bio)analytical assays and highlight their great potential to face the current demands of chemical sensing in several fields, such as disease diagnosis, food safety, environmental monitoring, among others. After that, we address the general advantages of nanosized MIPs over macro/micro-MIP materials, such as higher affinity toward target analytes and improved binding kinetics. Then, we provide a general overview on hydrogel properties and their great advantages for applications in the field of Sensors, followed by a brief description on current popular routes for synthesis of imprinted hydrogel nanospheres targeting large biomolecules, namely precipitation polymerization and solid-phase synthesis, along with fruitful combination with epitope imprinting as reliable approaches for developing optimized protein-imprinted materials. In the second part of the review, we have provided the state of the art on the application of MIP nanogels for screening macromolecules with sensors having different transduction modes (optical, electrochemical, thermal, etc.) and design formats for single use, reusable, continuous monitoring, and even multiple analyte detection in specialized laboratories or in situ using mobile technology. Finally, we explore aspects about the development of this technology and its applications and discuss areas of future growth.

PCL/PEO Polymer Membrane Prevents Biofouling in Wearable Detection Sensors

Technological advances in biosensing offer extraordinary opportunities to transfer technologies from a laboratory setting to clinical point-of-care applications. Recent developments in the field have focused on electrochemical and optical biosensing platforms. Unfortunately, these platforms offer relatively poor sensitivity for most of the clinically relevant targets that can be measured on the skin. In addition, the non-specific adsorption of biomolecules (biofouling) has proven to be a limiting factor compromising the longevity and performance of these detection systems. Research from our laboratory seeks to capitalize on analyte selective properties of biomaterials to achieve enhanced analyte adsorption, enrichment, and detection. Our goal is to develop a functional membrane integrated into a microfluidic sampling interface and an electrochemical sensing unit. The membrane was manufactured from a blend of Polycaprolactone (PCL) and Polyethylene oxide (PEO) through a solvent casting evaporation method. A microfluidic flow cell was developed with a micropore array that allows liquid to exit from all pores simultaneously, thereby imitating human perspiration. The electrochemical sensing unit consisted of planar gold electrodes for the monitoring of nonspecific adsorption of proteins utilizing Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). The solvent casting evaporation technique proved to be an effective method to produce membranes with the desired physical properties (surface properties and wettability profile) and a highly porous and interconnected structure. Permeability data from the membrane sandwiched in the flow cell showed excellent permeation and media transfer efficiency with uniform pore activation for both active and passive sweat rates. Biofouling experiments exhibited a decrease in the extent of biofouling of electrodes protected with the PCL/PEO membrane, corroborating the capacity of our material to mitigate the effects of biofouling.

Nanomaterial interfaces designed with different biorecognition elements for biosensing of key foodborne pathogens

Foodborne diseases caused by pathogen bacteria are a serious problem toward the safety of human life in a worldwide. Conventional methods for pathogen bacteria detection have several handicaps, including trained personnel requirement, low sensitivity, laborious enrichment steps, low selectivity, and long-term experiments. There is a need for precise and rapid identification and detection of foodborne pathogens. Biosensors are a remarkable alternative for the detection of foodborne bacteria compared to conventional methods. In recent years, there are different strategies for the designing of specific and sensitive biosensors. Researchers activated to develop enhanced biosensors with different transducer and recognition elements. Thus, the aim of this study was to provide a topical and detailed review on aptamer, nanofiber, and metal organic framework-based biosensors for the detection of food pathogens. First, the conventional methods, type of biosensors, common transducer, and recognition element were systematically explained. Then, novel signal amplification materials and nanomaterials were introduced. Last, current shortcomings were emphasized, and future alternatives were discussed.

Therapeutic potential of marine peptides in malignant melanoma

Malignant melanoma is the most dangerous type of skin cancer. It is becoming more common globally and is increasingly resistant to treatment options. Despite extensive research into its pathophysiology, there are still no proven cures for metastatic melanoma. Unfortunately, current treatments are frequently ineffective and costly, and have several adverse effects. Natural substances have been extensively researched for their anti-MM capabilities. Chemoprevention and adjuvant therapy with natural products is an emerging strategy to prevent, cure or treat melanoma. Numerous prospective drugs are found in aquatic species, providing a plentiful supply of lead cytotoxic chemicals for cancer treatment. Anticancer peptides are less harmful to healthy cells and cure cancer through several different methods, such as altered cell viability, apoptosis, angiogenesis/metastasis suppression, microtubule balance disturbances and targeting lipid composition of the cancer cell membrane. This review addresses marine peptides as effective and safe treatments for MM and details their molecular mechanisms of action.

Integrated Device Based on a Sudomotor Nanomaterial for Sweat Detection

The compositions of sweat and blood are related. Therefore, sweat is an ideal noninvasive test body fluid that could replace blood for linear detection of many biomarkers, especially blood glucose. However, access to sweat samples remains limited to physical exercise, thermal stimulation, or electrical stimulation. Despite intensive research, a continuous, innocuous, and stable method for sweat stimulation and detection has not yet been developed. In this study, a nanomaterial for a sweat-stimulating gel based on the transdermal drug delivery system is presented, which transports acetylcholine chloride into the receptors of sweat glands to achieve the function of biological stimulation of skin sweating. The nanomaterial was applied to a suitable integrated sweat glucose detection device for noninvasive blood glucose monitoring. The total amount of evaporated sweat enabled by the nanomaterial is up to 35 μL·cm^-2 for 24 h, and the device detects up to 17.65 μM glucose under optimal conditions, showing stable performance regardless of the user's activity level. In addition, the in vivo test was performed and compared with several studies and products, which showed excellent detection performance and osmotic relationship. The nanomaterial and associated integrated device represent a significant advance in continuous passive sweat stimulation and noninvasive sweat glucose measurement for point-of-care applications.

Recent advances in isolation and detection of exosomal microRNAs related to Alzheimer's disease

Alzheimer's disease, a progressive neurological condition, is associated with various internal and external risk factors in the disease's early stages. Early diagnosis of Alzheimer's disease is essential for treatment management. Circulating exosomal microRNAs could be a new class of valuable biomarkers for early Alzheimer's disease diagnosis. Different kinds of biosensors have been introduced in recent years for the detection of these valuable biomarkers. Isolation of the exosomes is a crucial step in the detection process which is traditionally carried out by multi-step ultrafiltration. Microfluidics has improved the efficiency and costs of exosome isolation by implementing various effects and forces on the nano and microparticles in the microchannels. This paper reviews recent advancements in detecting Alzheimer's disease related exosomal microRNAs based on methods such as electrochemical, fluorescent, and SPR. The presented devices' pros and cons and their efficiencies compared with the gold standard methods are reported. Moreover, the application of microfluidic devices to detect Alzheimer's disease related biomarkers is summarized and presented. Finally, some challenges with the performance of novel technologies for isolating and detecting exosomal microRNAs are addressed.

A Connected World: System-Level Support Through Biosensors

The goal of protecting the health of future generations is a blueprint for future biosensor design. Systems-level decision support requires that biosensors provide meaningful service to society. In this review, we summarize recent developments in cyber physical systems and biosensors connected with decision support. We identify key processes and practices that may guide the establishment of connections between user needs and biosensor engineering using an informatics approach. We call for data science and decision science to be formally connected with sensor science for understanding system complexity and realizing the ambition of biosensors-as-a-service. This review calls for a focus on quality of service early in the design process as a means to improve the meaningful value of a given biosensor. We close by noting that technology development, including biosensors and decision support systems, is a cautionary tale. The economics of scale govern the success, or failure, of any biosensor system.

Recent Advances in Electrochemiluminescence Biosensors for Mycotoxin Assay

Rapid and efficient detection of mycotoxins is of great significance in the field of food safety. In this review, several traditional and commercial detection methods are introduced, such as high-performance liquid chromatography (HPLC), liquid chromatography/mass spectrometry (LC/MS), enzyme-linked immunosorbent assay (ELISA), test strips, etc. Electrochemiluminescence (ECL) biosensors have the advantages of high sensitivity and specificity. The use of ECL biosensors for mycotoxins detection has attracted great attention. According to the recognition mechanisms, ECL biosensors are mainly divided into antibody-based, aptamer-based, and molecular imprinting techniques. In this review, we focus on the recent effects towards the designation of diverse ECL biosensors in mycotoxins assay, mainly including their amplification strategies and working mechanism.

Therapeutic targeting of the tumor microenvironments with cannabinoids and their analogs: Update on clinical trials

Cancer is a major global public health concern that affects both industrialized and developing nations. Current cancer chemotherapeutic options are limited by side effects, but plant-derived alternatives and their derivatives offer the possibilities of enhanced treatment response and reduced side effects. A plethora of recently published articles have focused on treatments based on cannabinoids and cannabinoid analogs and reported that they positively affect healthy cell growth and reverse cancer-related abnormalities by targeting aberrant tumor microenvironments (TMEs), lowering tumorigenesis, preventing metastasis, and/or boosting the effectiveness of chemotherapy and radiotherapy. Furthermore, TME modulating systems are receiving much interest in the cancer immunotherapy field because it has been shown that TMEs have significant impacts on tumor progression, angiogenesis, invasion, migration, epithelial to mesenchymal transition, metastasis and development of drug resistance. Here, we have reviewed the effective role of cannabinoids, their analogs and cannabinoid nano formulations on the cellular components of TME (endothelial cells, pericytes, fibroblast and immune cells) and how efficiently it retards the progression of carcinogenesis is discussed. The article summarizes the existing research on the molecular mechanisms of cannabinoids regulation of the TME and finally highlights the human studies on cannabinoids' active interventional clinical trials. The conclusion outlines the need for future research involving clinical trials of cannabinoids to demonstrate their efficacy and activity as a treatment/prevention for various types of human malignancies.

All-solid-state potentiometric salicylic acid sensor for in-situ measurement of plant

Using PEDOT as the conductive polymer, an innovative small-scale sensor for directly measuring salicylate ions in plants was developed, which avoided the complicated sample pretreatment of traditional analytical methods and realized the rapid detection of salicylic acid. The results demonstrate that this all-solid-state potentiometric salicylic acid sensor is easy to miniaturize, has a longer lifetime (≥1 month), is more robust, and can be directly used for the detection of salicylate ions in real samples without any additional pretreatment. The developed sensor has a good Nernst slope (63.6 ± 0.7 mV/decade), the linear range is 10^-2 ~ 10^-6 M, and the detection limit can reach (2.8 × 10^-7 M). The selectivity, reproducibility, and stability of the sensor were evaluated. The sensor can perform stable, sensitive, and accurate in situ measurement of salicylic acid in plants, and it is an excellent tool for determining salicylic acid ions in plants in vivo.

A novel electrochemical micro-titration method for quantitative evaluation of the DPPH free radical scavenging capacity of caffeic acid

In this report, the stoichiometric ratio (R) for the interaction of diphenylpicrylhydrazyl (DPPH) radicals with the antioxidant was employed as an evaluation index for the DPPH radical scavenging activity of antioxidants. This evaluation index was related only to the stoichiometric relationship of DPPH radicals with the antioxidant and had no relationship with the initial DPPH amount and the sample volume, which could offer a solution to the problem of poor comparability of EC50 values under different conditions. A novel electrochemical micro-titration method was proposed for the determination of the stoichiometric ratio (R) for the interaction of DPPH radicals with the antioxidant. This electrochemical micro-titration model was verified using caffeic acid as the DPPH radical scavenger, with the stoichiometric ratio (R) of DPPH radicals to caffeic acid determined to be in the range of 2.003–2.046. The calculated EC50 values were 0.513, 1.011, and 1.981 × 10–5 mol/L for 2.10, 4.05, and 8.02 × 10–7 moL of added DPPH radicals, respectively. The proposed method showed no differences from the conventional method, but had better precision and reliability, and used a smaller amount of sample.

In-situ synthesis of Pt nanoparticles/reduced graphene oxide/cellulose nanohybrid for nonenzymatic glucose sensing

In recent years, nanocellulose-based bioinorganic nanohybrids have been exploited in numerous applications due to their unique nanostructure, excellent catalytic properties, and good biocompatibility. To the best of our knowledge, this is the first report on the simple and effective synthesis of graphene/cellulose (RGO/CNC) matrix-supported platinum nanoparticles (Pt NPs) for nonenzymatic electrochemical glucose sensing. The Pt/RGO/CNC nanohybrid presented a porous network structure, in which Pt NPs, RGO, and CNCs were integrated well. Here, cellulose nanocrystals act as a biocompatible framework for wrapped RGO and monodispersed Pt nanoparticles, effectively preventing the restacking of graphene during reduction. The superior glucose sensing performance of Pt/RGO/CNC modified glass carbon electrode (GCE) was achieved with a linear concentration range from 0.005 to 8.5 mM and a low detection limit of 2.1 μM. Moreover, the Pt/RGO/CNC/GCE showed remarkable sensitivity, selectivity, durability, and reproducibility. The obtained results indicate that the CNCs-based bioinorganic nanohybrids could be a promising electrode material in electrochemical biosensors.