Electrochemical sensor and biosensor platforms based on advanced nanomaterials for biological and biomedical applications

Label-Free detection of Poly-Cystic Ovarian Syndrome using a highly conductive 2-D rGO/MoS2/PANI nanocomposite based immunosensor

Polycystic ovarian syndrome (PCOS) is an endocrinal disorder characterized by multiple tiny cysts, amenorrhea, dysmenorrhea, hirsutism, and infertility. The current diagnostic tools comprise of expensive, time-consuming ultrasonography to serological test, which have low patient compliance. To address these limitations, we have developed a highly sensitive, cost effective and ultrafast immunosensor for the diagnosis of PCOS. Herein, we have fabricated a 2-D electro conductive composites of reduced Graphene oxide (rGO), Molybdenum disulfide (MoS2), and Polyaniline (PANI) as electrode material. Furthermore, for detecting an early and non-cyclic biomarker of PCOS, i.e. anti-Mullerian hormone (AMH). We utilize the specific antigen-antibody mechanism, in which monoclonal Anti-AMH antibodies were covalently immobilized using EDC-NHS chemistry on electrode. The developed biosensor was physicochemical and electrochemically characterized to demonstrate its efficiency. Further we have investigated the biosensor's performance with Cyclic Voltammetry, Differential Pulse Voltammetry, and Electrochemical Impedance Spectroscopy. We have validated that under the optimized condition the immunosensor exhibits higher sensitivity with a LOD of ∼ 2.0 ng/mL with a linear range up to 100 ng/mL. Furthermore, this immunosensor works efficiently with a lower sample volume (>5 μL), which provides a sensitive, reproducible, low-cost, rapid analysis to detect AMH level in PCOS diagnosis.

A novel biosensing strategy on the dynamic and on-site detection of Vibrio coralliilyticus eDNA for coral health warnings

Heat stress and coral diseases are the predominant factors causing the degradation of coral reef ecosystems. Over recent years, Vibrio coralliilyticus was identified as a temperature-dependent pathogen causing tissue lysis in Pocillopora damicornis and one of the primary pathogens causing bleaching and mortality in other corals. Yet current detection techniques for V. coralliilyticus rely primarily on qPCR and ddPCR, which cannot meet the requirements for non-invasive and real-time detection. Herein, we developed an effective electrochemical biosensor modified by an Au-MoS2/rGO (AMG) nanocomposites and a specific capture probe to dynamically detect V. coralliilyticus environment DNA (eDNA) in aquarium experiments, with a lower limit of detection (0.28 fM) for synthetic DNA and a lower limit of quantification (9.8 fg/µL, ∼0.86 copies/µL) for genomic DNA. Its reliability and accuracy were verified by comparison with the ddPCR method (P > 0.05). Notably, coral tissue started to lyse at only 29 °C when the concentration of V. coralliilyticus increased abruptly to 880 copies/µL, indicating the biosensor could reflect the types of pathogen and health risks of corals under heat stress. Overall, the novel and reliable electrochemical biosensing technology provides an efficient strategy for the on-site monitoring and early warning of coral health in the context of global warming.

Recent advances in gold nanoparticles-based biosensors for tuberculosis determination

Tuberculosis (TB) is one of the major killer diseases affecting lung parenchymal tissues. Mycobacterium tuberculosis (Mtb) is the bacterium that causes it. It most commonly affects the lungs, although it can affect any part of the body, including the stomach, glands, bones, and nervous system. Although anti-mycobacterial drugs are available, it remains a major threat to public health due to the rise of drug-resistant strains, and early and accurate diagnosis is very important. Currently, research science and medical communities are focusing on the use of cost-effective biosensors to manage human biological processes and assess accurate health diagnostics. Due to their high sensitivity in chemical and biological assays, nanomaterials have been considered in the field of biosensors for better diagnosis, and among them, gold nanoparticles (AuNPs) can play an important role in accelerating the diagnosis of TB. Superior biocompatibility, conductivity, catalytic properties, high surface-to-volume ratio, and high density enable their widespread use in the fabrication of biosensors. This review evaluates the diagnostic accuracy of AuNP-based biosensors for the detection of Mtb. According to different transducers of biosensors, their structure, performance, advantages and limitations are summarized and compared. Moreover, the upcoming challenges in their analytical performance have been highlighted and the strategies to overcome those challenges have been briefly discussed.

Nanomaterials revolutionize biosensing: 0D-3D designs for ultrasensitive detection of microorganisms and viruses

Various diseases caused by harmful microorganisms and viruses have caused serious harm and huge economic losses to society. Thus, rapid detection of harmful microorganisms and viruses is necessary for disease prevention and treatment. Nanomaterials have unique properties that other materials do not possess, such as a small size effect and quantum size effect. Introducing nanomaterials into biosensors improves the performance of biosensors for faster and more accurate detection of microorganisms and viruses. This review aims to introduce the different kinds of biosensors and the latest advances in the application of nanomaterials in biosensors. In particular, this review focuses on describing the physicochemical properties of zero-, one-, two-, and three-dimensional nanostructures as well as nanoenzymes. Finally, this review discusses the applications of nanobiosensors in the detection of microorganisms and viruses and the future directions of nanobiosensors.

Designing Nanocomposite-Based Electrochemical Biosensors for Diabetes Mellitus Detection: A Review

This review will unveil the development of a new generation of electrochemical sensors utilizing a transition-metal-oxide-based nanocomposite with varying morphology. There has been considerable discussion on the role of transition metal oxide-based nanocomposite, including iron, nickel, copper, cobalt, zinc, platinum, manganese, conducting polymers, and their composites, in electrochemical and biosensing applications. Utilizing these materials to detect glucose and hydrogen peroxide selectively and sensitively with the correct chemical functionalization is possible. These transition metals and their oxide nanoparticles offer a potential method for electrode modification in sensors. Nanotechnology has made it feasible to develop nanostructured materials for glucose and H2O2 biosensor applications. Highly sensitive and selective biosensors with a low detection limit can detect biomolecules at nanomolar to picomolar (10-9 to 10-12 molar) concentrations to assess physiological and metabolic parameters. By mixing carbon-based materials (graphene oxide) with inorganic nanoparticles, nanocomposite biosensor devices with increased sensitivity can be made using semiconducting nanoparticles, quantum dots, organic polymers, and biomolecules.

Fabrication of a salivary amylase electrochemical sensor based on surface confined MWCNTs/β-cyclodextrin/starch architect for dental caries in clinical samples

Salivary α-amylase (α-ALS) has drawn attention as a possible bioindicator for dental caries. Herein, combining the synergistic properties of multi-walled carbon nanotubes (MWCNTs), β-cyclodextrin (β-CD) and starch, an electrochemical sensor is constructed employing ferrocene (FCN) as an electrochemical indicator to oversee the progression of the enzymatic catalysis of α-ALS. The method involves a two-step chemical reaction sequence on a screen-printed carbon electrode (SPCE). X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, Field emission scanning electron microscope (FE-SEM), and Dynamic light scattering (DLS) were used to characterize the synthesized material, while Static water Contact angle measurements, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were performed to monitor each step of sensor fabrication. The electrochemical sensor permitted to detect α-ALS within the linear range of 0.5-280 U mL-1, revealing detection (LOD), and quantification (LOQ) values of 0.041 U mL-1, and 0.159 U mL-1, respectively. Remarkably, the sensor demonstrated exceptional specificity and selectivity, effectively discriminating against other interfering substances in saliva. Validation of the method involved analyzing α-ALS levels in artificial saliva with an accuracy range of 97 % to 103 %, as well as in real clinical saliva samples across various age groups.

Biofunctional photoelectrochemical/electrochemical immunosensor based on BiVO4/BiOI-MWCNTs and Au@PdPt for alpha-fetoprotein detection

A biofunctional immunosensor combining photoelectrochemical (PEC) and electrochemical (EC) was proposed for the quantitative detection of the liver cancer marker alpha-fetoprotein (AFP) in human blood. BiVO4/BiOI-MWCNTs photoactive materials were first prepared on conductive glass FTO, and the photoelectrode was functionalized by chitosan and glutaraldehyde. Then, the AFP capture antibody (Ab1) was successfully modified on the photoelectrode, and the label-free rapid detection of AFP antigen was achieved by PEC. In addition, Au@PdPt nanospheres were also used as a marker for binding to AFP detection antibody (Ab2). Due to the excellent catalytic properties of Au@PdPt in EC reaction, a signal increase in the EC response can be achieved when Ab2 binds to the AFP antigen, which ensures high sensitivity for the detection of AFP. The detection limits of PEC and EC are 0.050 pg/mL and 0.014 pg/mL, respectively. The sensor also possesses good specificity, stability and reproducibility, shows excellent performance in the detection of clinical samples and has good clinical applicability.

A Sensitive Enzymatic Electrochemical Biosensor for Cholesterol Based on Cobalt Ferrite@Molybdenum Disulfide/Gold Nanoparticles

Cholesterol is essential in biological systems, and the level of cholesterol in the body of a person acts as a diagnostic marker for a variety of diseases. So, in this work, we fabricated an enzymatic electrochemical biosensor for cholesterol using cobalt ferrite@molybdenum disulfide/gold nanoparticles (CoFe2O4@MoS2/Au). The synthesized composite was used for the determination of cholesterol by voltametric methods. The electroactive material CoFe2O4@MoS2/Au was successfully verified from the physiochemical studies such as XRD, Raman, FT-IR, and XPS spectroscopy along with morphological FESEM and HRTEM characterization. CoFe2O4@MoS2/Au showed outstanding dispersion in the aqueous phase, a large effective area, good biological compatibility, and superior electronic conductivity. The microflower-like CoFe2O4@MoS2/Au was confirmed by scanning electron microscopy. The image of transmission electron microscopy showed decoration of gold nanoparticles on CoFe2O4@MoS2 surfaces. Furthermore, a one-step dip-coating technique was used to build the biosensor used for cholesterol detection. In addition to acting as an enabling matrix to immobilize cholesterol oxidase (ChOx), CoFe2O4@MoS2/Au contributes to an increase in electrical conductivity. The differential pulse voltammetry method was used for the quantitative measurement of cholesterol. The calibration curve for cholesterol was linear in the concentration range of 5 to 100 μM, with a low limit of detection of 0.09 μM and sensitivity of 0.194 μA μM-1 cm-2. Furthermore, the biosensor demonstrates good practicability, as it was also employed for identifying cholesterol in real samples with acceptable selectivity and stability.

Implications of analytical nanoscience in pharmaceutical and biomedical fields: A critical view

This review summarizes recent progress performed in the design and application of analytical tools and methodologies using nanomaterials for pharmaceutical analysis, and specifically new nanomedicines at distinct phases of development and translation from preclinical to clinical stages. Over the last 10-15 years, a growing number of studies have utilized various nanomaterials, including carbon-based, metallic nanoparticles, polymeric nanomaterials, materials based on biological molecules, and composite nanomaterials as tools for improving the analysis of pharmaceutical products. New and more complex nanomaterials are currently being explored to influence different stages of the analytical process. These materials provide unique properties to support the extraction of analytes in complex samples, increase the selectivity and efficiency of chromatographic separations, and improve the analytical properties of many sensor applications. Indeed, nanomaterials, including electrochemical detection approaches and biosensing, are expanding at a remarkable rate. Furthermore, the analytical performance of numerous approaches to determine drugs in different matrices can be significantly improved in terms of precision, detection limits, selectivity, and time of analysis. However, the quality control and metrological characterization of the currently synthesized nanomaterials still depend on the development of new and improved analytical methodologies, and the application of specific and improved instrumentation. Therefore, there is still much to explore about the properties of nanomaterials which need to be determined even more precisely and accurately.

Precision in cancer diagnostics: ultra-sensitive detection of MCF-7 breast cancer cells by gold nanostructure-enhanced electrochemical biosensing

Timely identification of cancers is pivotal in optimizing treatment efficacy and reducing their widespread impact. This study introduces a novel biosensor for the sensitive electrochemical detection of cancer cells overexpressing mucin 1 (MUC1), a well-established model for breast cancer. The sensor substrate comprises gold columnar nanostructures obtained through glancing angle deposition (GLAD) of copper nanostructures, subsequently replaced by gold via a facile galvanic replacement process. Functionalizing these gold nanostructures with aptamers targeting the MUC1 glycoproteins, a prominent cancer biomarker, enables specific recognition of MCF-7 breast cancer cells. The proposed electrochemical sensing platform offers several advantages, including high selectivity, a wide linear range of detection, a low detection limit of 30 cells per mL, and long-term stability, rendering this sensor highly desirable for definitive breast cancer diagnosis.

Non-canonical CRISPR/Cas12a-based technology: A novel horizon for biosensing in nucleic acid detection

Nucleic acids are essential biomarkers in molecular diagnostics. The CRISPR/Cas system has been widely used for nucleic acid detection. Moreover, canonical CRISPR/Cas12a based biosensors can specifically recognize and cleave target DNA, as well as single-strand DNA serving as reporter probe, which have become a super star in recent years in the field of nucleic acid detection due to its high specificity, universal programmability and simple operation. However, canonical CRISPR/Cas12a based biosensors are hard to meet the requirements of higher sensitivity, higher specificity, higher efficiency, larger target scope, easier operation, multiplexing, low cost and diversified signal reading. Then, advanced non-canonical CRISPR/Cas12a based biosensors emerge. In this review, applications of non-canonical CRISPR/Cas12a-based biosensors in nucleic acid detection are summarized. And the principles, peculiarities, performances and perspectives of these non-canonical CRISPR/Cas12a based biosensors are also discussed.

Comparative analysis of electrochemical and optical sensors for detection of chronic wounds biomarkers: A review

Chronic wounds (CW) present a significant healthcare challenge due to their prolonged healing time and associated complications. To effectively treat these wounds and prevent further deterioration, monitoring their healing progress is crucial. Traditional wound assessment methods relying on visual inspection and subjective evaluation are prone to inter-observer variability. Biomarkers play a critical role in objectively evaluating wound status and predicting healing outcomes, providing quantitative measures of wound healing progress, inflammation, infection, and tissue regeneration. Recent attention has been devoted to identifying and validating CW biomarkers. Various studies have investigated potential biomarkers, including growth factors, cytokines, proteases, and extracellular matrix components, shedding light on the complex molecular and cellular processes within CW. This knowledge enables a more targeted and personalized approach to wound management. Accurate and sensitive techniques are necessary for detecting CW biomarkers. Thus, this review compares and discusses the use of electrochemical and optical sensors for biomarker determination. The advantages and disadvantages of these sensors are highlighted. Differences in detection capabilities and characteristics such as non-invasiveness, portability, high sensitivity, specificity, simplicity, cost-effectiveness, compatibility with point-of-care applications, and real-time monitoring of wound biomarkers will be pointed out and compared. In summary, this work provides an overview of CW, explores the emerging field of CW biomarkers, and discusses methods for detecting these biomarkers, with a specific focus on optical and electrochemical sensors. The potential of further research and development in this field for advancing wound care and improving patient outcomes will also be noted.

Electrochemical and optical (bio)sensors for analysis of antibiotic residuals

Antibiotic residuals in foods may lead to crucial health and safety issues in the human body. Rapid and in-time analysis of antibiotics using simple and sensitive techniques is in high demand. Among the most commonly applicable modalities, chromatography-based techniques like HPLC and LC-MS, along with immunological approaches, particularly ELISA have been exampled in the analysis of antibiotics. Despite being highly sensitive, these methods are considerably time-consuming, thus the presence of skilled personnel and costly equipment is essential. Nanomaterial-based (bio)sensors, however, are de novo analytical equipment with some beneficial characteristics, such as simplicity, low price, on-site, high accuracy, and sensitivity for the detection of analytes. This review aimed to collect the latest developments in NM-based sensors and biosensors for the observation of highly used antibiotics like Vancomycin (Van), Linezolid (Lin), and Clindamycin (Clin). The current challenges and developmental perspectives are also debated in detail for future research directions.

Machine learning-based models to predict aquatic ecological risk for engineered nanoparticles: using hazard concentration for 5% of species as an endpoint

Assessment and prediction for the ecotoxicity of engineered nanoparticles (ENPs) at the community or ecosystem levels represents a critical step toward a comprehensive understanding of the ecological risks of ENPs. Current studies on predicting the ecotoxicity of ENPs primarily focus on the cellular and individual levels, with limited exploration at the community or ecosystem levels. Herein, we present the first of the reports for the direct prediction of aquatic ecological risk for ENPs at the community level using machine learning (ML) approaches in the field of computational toxicology. Specifically, we extensively collected the threshold concentrations of twelve ENPs including metal- and carbon-based nanoparticles for aquatic species, i.e., hazardous concentrations at which 5% of species are harmed (HC5), established by a species sensitivity distribution. Afterwards, we used eight supervised ML methods including Adaboost, artificial neural network, C4.5 decision tree, K-nearest neighbor, logistic regression, Naive Bayes, random forest, and support vector machine to develop nine classification models and four regression models, respectively, for the qualitative and quantitative prediction of HC5. The evaluation of model performance yielded the internal validation accuracy of all classification models ranging from 71.4 to 100%, and the determination coefficient of regression models ranging from 0.702 to 0.999, indicating that the developed models showed good performance. By using a cross-validation method and an application domain characterization, the selected models were further validated to have powerful predictive ability. Furthermore, the incorporation of three nanostructural descriptors (metal oxide sublimation enthalpy, zeta potential, and specific surface area) linked to toxicity mechanisms (the release of metal ions, the stability of dispersions of particles in aqueous suspensions, and the surface properties of the material) effectively enhanced the prediction power and mechanistic interpretability of the selected models. These findings would not only be beneficial in the screening of ENPs with potential high ecological risks that need to be tested as a priority but also contribute to the development of environmental regulations and standards for ENPs.

Biosensing Platforms for Cardiac Biomarker Detection

Myocardial infarction (MI) is a cardiovascular disease that occurs when there is an elevated demand for myocardial oxygen as a result of the rupture or erosion of atherosclerotic plaques. Globally, the mortality rates associated with MI are steadily on the rise. Traditional diagnostic biomarkers employed in clinical settings for MI diagnosis have various drawbacks, prompting researchers to investigate fast, precise, and highly sensitive biosensor platforms and technologies. Biosensors are analytical devices that combine biological elements with physicochemical transducers to detect and quantify specific compounds or analytes. These devices play a crucial role in various fields including healthcare, environmental monitoring, food safety, and biotechnology. Biosensors developed for the detection of cardiac biomarkers are typically electrochemical, mass, and optical biosensors. Nanomaterials have emerged as revolutionary components in the field of biosensing, offering unique properties that significantly enhance the sensitivity and specificity of the detection systems. This review provides a comprehensive overview of the advancements and applications of nanomaterial-based biosensing systems. Beginning with an exploration of the fundamental principles governing nanomaterials, we delve into their diverse properties, including but not limited to electrical, optical, magnetic, and thermal characteristics. The integration of these nanomaterials as transducers in biosensors has paved the way for unprecedented developments in analytical techniques. Moreover, the principles and types of biosensors and their applications in cardiovascular disease diagnosis are explained in detail. The current biosensors for cardiac biomarker detection are also discussed, with an elaboration of the pros and cons of existing platforms and concluding with future perspectives.

COVID-19 cooling: Nanostrategies targeting cytokine storm for controlling severe and critical symptoms

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants continue to wreak havoc worldwide, the "Cytokine Storm" (CS, also known as the inflammatory storm) or Cytokine Release Syndrome has reemerged in the public consciousness. CS is a significant contributor to the deterioration of infected individuals. Therefore, CS control is of great significance for the treatment of critically ill patients and the reduction of mortality rates. With the occurrence of variants, concerns regarding the efficacy of vaccines and antiviral drugs with a broad spectrum have grown. We should make an effort to modernize treatment strategies to address the challenges posed by mutations. Thus, in addition to the requirement for additional clinical data to monitor the long-term effects of vaccines and broad-spectrum antiviral drugs, we can use CS as an entry point and therapeutic target to alleviate the severity of the disease in patients. To effectively combat the mutation, new technologies for neutralizing or controlling CS must be developed. In recent years, nanotechnology has been widely applied in the biomedical field, opening up a plethora of opportunities for CS. Here, we put forward the view of cytokine storm as a therapeutic target can be used to treat critically ill patients by expounding the relationship between coronavirus disease 2019 (COVID-19) and CS and the mechanisms associated with CS. We pay special attention to the representative strategies of nanomaterials in current neutral and CS research, as well as their potential chemical design and principles. We hope that the nanostrategies described in this review provide attractive treatment options for severe and critical COVID-19 caused by CS.

Influence of titanium nanoscale surface roughness on fibrinogen and albumin protein adsorption kinetics and platelet responses

Biomaterials with nanoscale topography have been increasingly investigated for medical device applications to improve tissue-material interactions. This study assessed the impact of nanoengineered titanium surface domain sizes on early biological responses that can significantly affect tissue interactions. Nanostructured titanium coatings with distinct nanoscale surface roughness were deposited on quartz crystal microbalance with dissipation (QCM-D) sensors by physical vapor deposition. Physico-chemical characterization was conducted to assess nanoscale surface roughness, nano-topographical morphology, wettability, and atomic composition. The results demonstrated increased projected surface area and hydrophilicity with increasing nanoscale surface roughness. The adsorption properties of albumin and fibrinogen, two major plasma proteins that readily encounter implanted surfaces, on the nanostructured surfaces were measured using QCM-D. Significant differences in the amounts and viscoelastic properties of adsorbed proteins were observed, dependent on the surface roughness, protein type, protein concentration, and protein binding affinity. The impact of protein adsorption on subsequent biological responses was also examined using qualitative and quantitative in vitro evaluation of human platelet adhesion, aggregation, and activation. Qualitative platelet morphology assessment indicated increased platelet activation/aggregation on titanium surfaces with increased roughness. These data suggest that nanoscale differences in titanium surface roughness influence biological responses that may affect implant integration.

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

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

Biosensing of DNA through difference in interaction between microparticle and glass plate based on particle dissociation in a coupled acoustic-gravitational field

A novel approach for detecting DNA without labeling the target DNA was developed based on the particle dissociation behavior in a combined acoustic-gravitational field. The particles, which are tethered on a glass plate via intermolecular interactions (Fbind), are dissociated by the resultant force of the acoustic radiation force (Fac), which is a function of the applied voltage (V), and the sedimentation force. In this system, V required for particle dissociation is dependent on Fbind. The differences in Fbind were exploited for detecting the target DNA. A glass plate and polystyrene (PS) particles were respectively modified with anchor and capture DNAs. The target DNA induces immobilization of the PS particles on the glass plate through sandwich hybridization, with a large accompanying Fbind. In the absence of the target DNA, the anchor DNA on the glass plate interacted weakly with the capture DNA on the PS particles via direct binding (small Fbind). The particle dissociation behavior varies based on the concentration of the target DNA due to changes in the ratio of the PS particles tethered through direct binding and sandwich hybridization. Target DNA with a length exceeding 12 base pairs (bps) can be detected on the picomolar scale at concentrations of 10-12 to 10-5 M. This detection scheme was applied to a specific sequence of HIV-2 with 20 bps, achieving a picomolar detection limit.

Advances in biomedical systems based on microneedles: design, fabrication, and application

Wearable devices have become prevalent in biomedical studies due to their convenient portability and potential utility in biomarker monitoring for healthcare. Accessing interstitial fluid (ISF) across the skin barrier, microneedle (MN) is a promising minimally invasive wearable technology for transdermal sensing and drug delivery. MN has the potential to overcome the limitations of conventional transdermal drug administration, making it another prospective mode of drug delivery after oral and injectable. Subsequently, combining MN with multiple sensing approaches has led to its extensive application to detect biomarkers in ISF. In this context, employing MN platforms and control schemes to merge diagnostic and therapeutic capabilities into theranostic systems will facilitate on-demand therapy and point-of-care diagnostics, paving the way for future MN technologies. A comprehensive analysis of the growing advances of microneedles in biomedical systems is presented in this review to summarize the latest studies for academics in the field and to offer for reference the issues that need to be addressed in MN application for healthcare. Covering an array of novel studies, we discuss the following main topics: classification of microneedles in the biomedical field, considerations of MN design, current applications of microneedles in diagnosis and therapy, and the regulatory landscape and prospects of microneedles for biomedical applications. This review sheds light on the significance of microneedle-based innovations, presenting an analysis of their potential implications and contributions to the community of wearable healthcare technologies. The review provides a comprehensive understanding of the field's current state and potential, making it a valuable resource for academics and clinicians seeking to harness the full potential of MN applications.

Fouling-resistant electrode for electrochemical sensing based on covalent-organic frameworks TpPA-1 dispersed cabon nanotubes

The key problem that limits the practical applications of nonenzymatic electrochemical sensors in biological media, is the biofouling and chemical fouling of electrodes due to the adsorption of biological molecules and oxidation (reduction) products. Electrode fouling will cause low accuracy, poor stability, and low sensitivity. Here, a simple and efficient antifouling electrode was demonstrated for electrochemical sensing based on covalent-organic framework (COF) TpPA-1 and carboxylic multi-walled carbon nanotubes (CNT) composites. COF TpPA-1 possesses abundant hydrophilic groups, which assisted the dispersion of CNT in water and formed uniform composites by π-π interaction. In addition, the introduction of CNT into the composites improved the electron transfer rate of COF TpPA-1. The antifouling interface was characterized by electrochemistry, contact angle measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The electrode showed good chemical and bio-fouling resistant performance for the electrochemical detection of β-nicotinamide adenine dinucleotide (NADH) and uric acid (UA) in real serum samples.

Diagnosis and screening of abnormal hemoglobins

Hemoglobin (Hb) abnormalities, such as thalassemia and structural Hb variants, are among the most prevalent inherited diseases and are associated with significant mortality and morbidity worldwide. However, there were not comprehensive reviews focusing on different clinical analytical techniques, research methods and artificial intelligence (AI) used in clinical screening and research on hemoglobinopathies. Hence the review offers a comprehensive summary of recent advancements and breakthroughs in the detection of aberrant Hbs, research methods and AI uses as well as the present restrictions anddifficulties in hemoglobinopathies. Recent advances in cation exchange high performance liquid chromatography (HPLC), capillary zone electrophoresis (CZE), isoelectric focusing (IEF), flow cytometry, mass spectrometry (MS) and polymerase chain reaction (PCR) etc have allowed for the definitive detection by using advanced AIand portable point of care tests (POCT) integrating with smartphone microscopic classification, machine learning (ML) model, complete blood counts (CBC), imaging-based method, speedy immunoassay, and electrochemical-, microfluidic- and sensing-related platforms. In addition, to confirm and validate unidentified and novel Hbs, highly specialized genetic based techniques like PCR, reverse transcribed (RT)-PCR, DNA microarray, sequencing of genomic DNA, and sequencing of RT-PCR amplified globin cDNA of the gene of interest have been used. Hence, adequate utilization and improvement of available diagnostic and screening technologies are important for the control and management of hemoglobinopathies.

Nanobiosensors: Concepts and Emerging Clinical Applications

Biosensors have been one of the most fascinating topics for scientists for a long time. This is because biological moieties are multifaceted and are unswervingly related to the presence of a healthy atmosphere. The biosensor approach has also endured profound changes in recent years. Biosensors have been emphasized for various applications, including food quality estimation, surveillance systems, and health and metabolic abnormality diagnostics. The advances in nanotechnology have led to a considerable potential to enhance biosensors' sensitivity, robustness, and anti-interference capabilities. Several new nanomaterials (such as nanoparticles, nanotubes, nanorods, and nanowires) have been fabricated due to the evolution of nanotechnology, and their unique features are gradually being identified, allowing for much faster detection and reproducibility. Biosensor performance has also been enhanced substantially as a result of their use. Because of their capacity to detect a wide range of compounds at deficient concentrations, nanobiosensors have sparked much interest. This article discusses biosensors based on various nanomaterials, their evolution, accompanying features, and their applications in multiple fields.

Microarray-Based Electrochemical Biosensing

Microarrays are widely utilized in bioanalysis. Electrochemical biosensing techniques are often applied in microarray-based assays because of their simplicity, low cost, and high sensitivity. In such systems, the electrodes and sensing elements are arranged in arrays, and the target analytes are detected electrochemically. These sensors can be utilized for high-throughput bioanalysis and the electrochemical imaging of biosamples, including proteins, oligonucleotides, and cells. In this chapter, we summarize recent progress on these topics. We categorize electrochemical biosensing techniques for array detection into four groups: scanning electrochemical microscopy, electrode arrays, electrochemiluminescence, and bipolar electrodes. For each technique, we summarize the key principles and discuss the advantages, disadvantages, and bioanalysis applications. Finally, we present conclusions and perspectives about future directions in this field.

An Overview of Electrochemical Sensors Based on Transition Metal Carbides and Oxides: Synthesis and Applications

Sensors play vital roles in industry and healthcare due to the significance of controlling the presence of different substances in industrial processes, human organs, and the environment. Electrochemical sensors have gained more attention recently than conventional sensors, including optical fibers, chromatography devices, and chemiresistors, due to their better versatility, higher sensitivity and selectivity, and lower complexity. Herein, we review transition metal carbides (TMCs) and transition metal oxides (TMOs) as outstanding materials for electrochemical sensors. We navigate through the fabrication processes of TMCs and TMOs and reveal the relationships among their synthesis processes, morphological structures, and sensing performance. The state-of-the-art biological, gas, and hydrogen peroxide electrochemical sensors based on TMCs and TMOs are reviewed, and potential challenges in the field are suggested. This review can help others to understand recent advancements in electrochemical sensors based on transition metal oxides and carbides.

Enzyme-free electrochemical sensor platforms based on transition metal nanostructures for clinical diagnostics

The detection of emergent biomarkers is of key significance in numerous clinical, biological, and biomedical fields. Specifically, the design and development of potent electrochemical lactic acid and glucose sensing platforms are especially in great demand in a variety of industries, including those involved in clinical analysis, biomedicine, biological, food, cosmetics, pharmaceuticals, leather, sports, and chemical industries. Nanostructured transition metal-derived materials have opened the door to electrochemical sensors and biosensors due to their advantages of high surface-to-volume ratio, surface reaction activity, catalytic activity, and strong adsorption capability. The primary aim of the present minireview is to highlight the advancement of enzyme-free electrochemical sensor platforms based on transition metal-derived nanostructures with high electrocatalytic activity and sensing performance towards lactic acid and glucose in practical samples. The preparation approaches, structural and composition monitoring, fabrication of sensing electrodes, catalytic activity, sensing performance in real samples, and the exploration of sensing mechanisms are majorly concentrated on in most of our recent research studies. Moreover, state-of-the-art transition metal-derived nanostructure-derived electrochemical sensor platforms, critical comparison of the analytical performance of the sensor platforms, and the future perspectives of the enzyme-free electrochemical sensor for clinical diagnostics are described.

A biosensing array for multiplex clinical evaluation of glucose, creatinine, and uric acid

The multiplex and simultaneous determination of blood glucose, creatinine and uric acid is essential for the early screening of chronic diseases or regular disease monitoring. Here, we report for the first time a biosensing array for the multiplex and simultaneous determination of plasma glucose, creatinine and uric acid. The sensing electrodes are fabricated on a PET surface, including three working electrodes, one reference electrode, and one counter electrode. Each specific enzyme is immobilized on its corresponding working electrode. The biosensing array can exhibit high sensitivity and selectivity for the simultaneous determination of blood glucose, creatinine and uric acid in real blood samples, and the measurement results are accurate and consistent with those from the clinical biochemistry analyzer in the hospital. It is expected that this work could provide new avenues for the fundamental study of biosensing device construction, as well as practical applications of the detection of biomarkers in chronic diseases.

Wearable Clinic: From Microneedle-Based Sensors to Next-Generation Healthcare Platforms

The rapid development of wearable biosensing calls for next-generation devices that allow continuous, real-time, and painless monitoring of health status along with responsive medical treatment. Microneedles have exhibited great potential for the direct access of dermal interstitial fluid (ISF) in a minimally invasive manner. Recent studies of microneedle-based devices have evolved from conventional off-line detection to multiplexed, wireless, and integrated sensing. In this review, the classification and fabrication techniques of microneedles are first introduced, and then the representative examples of microneedles for transdermal monitoring with different sensing modalities are summarized. State-of-the-art advances in therapeutic and closed-loop systems are presented to formulate guidelines for the development of next-generation microneedle-based healthcare platforms. The potential challenges and prospects are discussed to pave a new avenue toward pragmatic applications in the real world.

Electrochemical miRNA-34a-based biosensor for the diagnosis of Alzheimer's disease

Alzheimer's disease (AD) is the most common dementia type and a leading cause of death and disability in the elderly. Diagnosis is expensive and invasive, urging the development of new, affordable, and less invasive diagnostic tools. The identification of changes in the expression of non-coding RNAs prompts the development of diagnostic tools to detect disease-specific blood biomarkers. Building on this idea, this work reports a novel electrochemical microRNA (miRNA) biosensor for the diagnosis of AD, based on carbon screen-printed electrodes (C-SPEs) modified with two gold nanostructures and a complementary anti-miR-34a oligonucleotide probe. This biosensor showed good target affinity, reflected on a 100 pM to 1 μM linearity range and a limit of detection (LOD) of 39 pM in buffer and 94 aM in serum. Moreover, the biosensor's response was not affected by serum compounds, indicating selectivity for miR-34a. The biosensor also detected miR-34a in the cell culture medium of a common AD model, stimulated with a neurotoxin to increase miR-34a secretion. Overall, the proposed biosensor makes a solid case for the introduction of a novel, inexpensive, and minimally invasive tool for the early diagnosis of AD, based on the detection of a circulating miRNA overexpressed in this pathology.

Signal Amplification Strategy Design in Nanozyme-Based Biosensors for Highly Sensitive Detection of Trace Biomarkers

Nanozymes show great promise in enhancing disease biomarker sensing by leveraging their physicochemical properties and enzymatic activities. These qualities facilitate signal amplification and matrix effects reduction, thus boosting biomarker sensing performance. In this review, recent studies from the last five years, concentrating on disease biomarker detection improvement through nanozyme-based biosensing are examined. This enhancement primarily involves the modulations of the size, morphology, doping, modification, electromagnetic mechanisms, electron conduction efficiency, and surface plasmon resonance effects of nanozymes for increased sensitivity. In addition, a comprehensive description of the synthesis and tuning strategies employed for nanozymes has been provided. This includes a detailed elucidation of their catalytic mechanisms in alignment with the fundamental principles of enhanced sensing technology, accompanied by the presentation of quantitatively analyzed results. Moreover, the diverse applications of nanozymes in strip sensing, colorimetric sensing, electrochemical sensing, and surface-enhanced Raman scattering have been outlined. Additionally, the limitations, challenges, and corresponding recommendations concerning the application of nanozymes in biosensing have been summarized. Furthermore, insights have been offered into the future development and outlook of nanozymes for biosensing. This review aims to serve not only as a reference for enhancing the sensitivity of nanozyme-based biosensors but also as a catalyst for exploring nanozyme properties and their broader applications in biosensing.

CRISPR/Cas and Argonaute-Based Biosensors for Pathogen Detection

Over the past few decades, pathogens have posed a threat to human security, and rapid identification of pathogens should be one of the ideal methods to prevent major public health security outbreaks. Therefore, there is an urgent need for highly sensitive and specific approaches to identify and quantify pathogens. Clustered Regularly Interspaced Short Palindromic Repeats CRISPR/Cas systems and Argonaute (Ago) belong to the Microbial Defense Systems (MDS). The guided, programmable, and targeted activation of nucleases by both of them is leading the way to a new generation of pathogens detection. We compare these two nucleases in terms of similarities and differences. In addition, we discuss future challenges and prospects for the development of the CRISPR/Cas systems and Argonaute (Ago) biosensors, especially electrochemical biosensors. This review is expected to afford researchers entering this multidisciplinary field useful guidance and to provide inspiration for the development of more innovative electrochemical biosensors for pathogens detection.

Hotspots and trends of electrochemical biosensor technology: a bibliometric analysis from 2003 to 2023

As a powerful tool for biological sensing, electrochemical biosensors have attracted much attention due to their ability to integrate biological recognition elements on an electrochemical interface and convert target analyte information into measurable electrochemical signals. Despite the abundance of literature published on the topic, no comprehensive surveys have been conducted to evaluate the area of electrochemical biosensors with bibliometric techniques. This paper employs VOSviewer to analyze and visualize literature from 2003 to 2023 in the Web of Science in order to gain an understanding of the development of the field of electrochemical biosensors in recent years. Co-occurrence and co-citation analysis are employed to identify research hotspots, trace evolutionary paths, and comprehend development trends in the field. Moreover, by analyzing highly cited and representative literature from different time periods, it is possible to recognize the major research hotspots and grasp the development pulse. The results of this study provide a comprehensive overview of the field of electrochemical biosensors and can be used to guide future research.

Recent advances in sensor-integrated brain-on-a-chip devices for real-time brain monitoring

Brain science has remained in the global spotlight as an important field of scientific and technological discovery. Numerous in vitro and in vivo animal studies have been performed to understand the pathological processes involved in brain diseases and develop strategies for their diagnosis and treatment. However, owing to species differences between animals and humans, several drugs have shown high rates of treatment failure in clinical settings, hindering the development of diagnostic and treatment modalities for brain diseases. In this scenario, microfluidic brain-on-a-chip (BOC) devices, which allow the direct use of human tissues for experiments, have emerged as novel tools for effectively avoiding species differences and performing screening for new drugs. Although microfluidic BOC technology has achieved significant progress in recent years, monitoring slight changes in neurochemicals, neurotransmitters, and environmental states in the brain has remained challenging owing to the brain's complex environment. Hence, the integration of BOC with new sensors that have high sensitivity and high selectivity is urgently required for the real-time dynamic monitoring of BOC parameters. As sensor-based technologies for BOC have not been summarized, here, we review the principle, fabrication process, and application-based classification of sensor-integrated BOC, and then summarize the opportunities and challenges for their development. Generally, sensor-integrated BOC enables real-time monitoring and dynamic analysis, accurately measuring minute changes in the brain and thus enabling the realization of in vivo brain analysis and drug development.

Facile immobilization of cholesterol oxidase on Pt,Ru-C nanocomposite and ionic liquid-modified carbon paste electrode for an efficient amperometric free cholesterol biosensing

In present work, the enzyme cholesterol oxidase (ChOx) was immobilized by Nafion® (Naf) on Pt,Ru-C nanocomposite and an ionic liquid (IL)-modified carbon paste electrode (CPE) in order to create cholesterol biosensor (Naf/ChOx/Pt,Ru-C/IL-CPE). The prepared working electrodes were characterized using scanning electron microscopy-energy-dispersive spectrometry, while their electrochemical performance was evaluated using electrochemical impedance spectroscopic, cyclic voltammetric, and amperometric techniques. Excellent synergism between IL 1-allyl-3-methylimidazolium dicyanamide ([AMIM][DCA]), Pt,Ru-C, and ChOx, as modifiers of CPE, offers the most pronounced analytical performance for improved cholesterol amperometric determination in phosphate buffer solution pH 7.50 at a working potential of 0.60 V. Under optimized experimental conditions, a linear relationship between oxidation current and cholesterol concentration was found for the range from 0.31 to 2.46 µM, with an estimated detection limit of 0.13 µM and relative standard deviation (RSD) below 5.5%. The optimized amperometric method in combination with the developed Naf/ChOx/Pt,Ru-C/IL-CPE biosensor showed good repeatability and high selectivity towards cholesterol biosensing. The proposed biosensor was successfully applied to determine free cholesterol in a human blood serum sample via its enzymatic reaction product hydrogen peroxide despite the presence of possible interferences. The percentage recovery ranged from 99.08 to 102.81%, while RSD was below 2.0% for the unspiked as well as the spiked human blood serum sample. The obtained results indicated excellent accuracy and precision of the method, concluding that the developed biosensor can be a promising alternative to existing commercial cholesterol tests used in medical practice.

Investigating on sensing mechanism of MoS2-FET biosensors in response to proteins

Field-effect transistor (FET) biosensors based on two-dimensional materials have gained extensive attention due to their high sensitivity, label-free detection capability, and fast response. Molybdenum disulfide (MoS2), with tunable bandgap, high surface-to-volume ratio, and smooth surface without dangling bonds, is a promising material for FET biosensors. Previous reports have demonstrated the fabrication of MoS2-FET biosensors and their high sensitivity detection of proteins. However, most prior research has focused on the realization of MoS2-FETs for detecting different kinds of proteins or molecules, while comprehensive analysis of the sensing mechanism and dominant device factors of MoS2-FETs in response to proteins is yet to investigate. In this study, we first fabricated MoS2-FET biosensor and detected different types of proteins (immunoglobulin G (IgG),β-actin, and prostate-specific antigen (PSA)). Secondly, we built the model of the device and analyzed the sensing mechanism of MoS2-FETs in response to proteins. Experimental and modeling results showed that the induced doping effect and gating effect caused by the target protein binding to the device surface were the major influential factors. Specifically, the channel doping concentration and gate voltage (Vg) offset exhibited monotonic change as the concentration of the protein solution increases. For example, the channel doping concentration increased up to ∼37.9% and theVgoffset was ∼-1.3 V with 10-7μgμl-1IgG. The change was less affected by the device size. We also investigated the effects of proteins with opposite acid-base properties (β-actin and PSA) to IgG on the device sensing mechanism.β-actin and PSA exhibited behavior opposite to that of IgG. Additionally, we studied the response behavior of MoS2-FETs with different dimensions and dielectric materials (channel length, MoS2thickness, dielectric layer thickness, dielectric layer material) to proteins. The underlying mechanisms were discussed in details. This study provides valuable guidelines for the design and application of MoS2-FET biosensors.

Metallic nanoplatforms for COVID-19 diagnostics: versatile applications in the pandemic and post-pandemic era

The COVID-19 pandemic, which originated in Hubei, China, in December 2019, has had a profound impact on global public health. With the elucidation of the SARS-CoV-2 virus structure, genome type, and routes of infection, a variety of diagnostic methods have been developed for COVID-19 detection and surveillance. Although the pandemic has been declared over, we are still significantly affected by it in our daily lives in the post-pandemic era. Among the various diagnostic methods, nanomaterials, especially metallic nanomaterials, have shown great potential in the field of bioanalysis due to their unique physical and chemical properties. This review highlights the important role of metallic nanosensors in achieving accurate and efficient detection of COVID-19 during the pandemic outbreak and spread. The sensing mechanisms of each diagnostic device capable of analyzing a range of targets, including viral nucleic acids and various proteins, are described. Since SARS-CoV-2 is constantly mutating, strategies for dealing with new variants are also suggested. In addition, we discuss the analytical tools needed to detect SARS-CoV-2 variants in the current post-pandemic era, with a focus on achieving rapid and accurate detection. Finally, we address the challenges and future directions of metallic nanomaterial-based COVID-19 detection, which may inspire researchers to develop advanced biosensors for COVID-19 monitoring and rapid response to other virus-induced pandemics based on our current achievements.

A polyoxometalate-based heterojunction nanozyme with peroxidase-mimic catalytic activity for sensitive biomolecule detection

Nanozymes are a class of nanomaterials that can specifically mimic the structures and catalytic activities as well as overcome limitations of natural enzymes and have hence been considered as a competitive alternative to natural enzymes. At present, plenty of nanozymes, especially those with peroxidase (POD)-like catalytic activity, have been extensively explored for biosensing. In this work, we proposed polyoxometalate-based heterojunction GdP₅W₃₀O₁₁₀@WS₂ nanoclusters (NCs) to exert intrinsic POD-like catalytic activity even under harsh catalytic conditions. Detailedly, GdP₅W₃₀O₁₁₀@WS₂ NCs possessing conducive POD-like catalytic activity can oxidize chromogenic substrates into colored substances in the presence of H₂O₂. On the strength of the POD-like catalytic activity of GdP₅W₃₀O₁₁₀@WS₂ NCs, a reliable analytical platform is then constructed after the optimization of catalytic conditions for the detection of H₂O₂, glutathione (GSH) and glucose via a simple TMB colorimetric strategy. This work advances the utilization of versatile polyoxometalate-based nanomaterials for biosensing, dramatically broadening the potential applications of other nanozyme-based biosensors.

Neutral - Eradication of As (III) and Congo red (CR) with green iron oxide (GIO) loaded chitosan(C) - (C - GIO) beads by a non - Thermal plasma jet via potential study

In this potential - study, the non - thermal atmospheric pressure plasma is utilized for the neutral - eradication of water contaminants. In the air ambient region, plasma induced reactive species, like as OH^•, O (O₂^-), H₂O₂ (OH^•+OH^•) & NO_x are performed for the oxidative and reductive transformation of As^III (H₃AsO₃) to As^V (H₂As O₄^-) & Fe₃O₄ (Fe³⁺) (C-GIO) to Fe₂O₃ (Fe²⁺). Whereas, the H₂O₂ & NO_x are quantified maximum (max.) in water, which is 144.24 & 111.82 μM, respectively. In the absence of plasma and plasma with C-GIO, the As^III was more eradicated, which is 64.01 and 100.00%. While, the C - GIO (catalyst) synergistic enhancement was performed and proved by the neutral - degradation of CR. Also, the As^V adsorbed on C-GIO adsorption capacity q_max and redox-adsorption yield were evaluated, which are 1.36 mg/g and 20.80 g/kWh, respectively. In this research, the waste material (GIO) was recycled, modified, and utilized for the neutral - eradication of water contaminates, which are organic (CR) and inorganic (As^III) toxicants by the controlling of H and OH^• under the interaction of plasma with catalyst (C-GIO). However, in this research, plasma can't adopt the acidic, which is controlled by the C-GIO via RONS. Moreover, in this eradicative study, various water pH alignments were performed, from neutral to acidic & neutral & base for toxicants removal. Furthermore, according to WHO norms, the arsenic level was reduced to 0.01 mg/l for environmental safety. The kinetic and isotherm studies were followed by the mono and multi-layer adsorption was performed on the surface of C - GIO beads, which is estimated by the fitting of rate limiting constant R² ≈ 1. Furthermore, the C-GIO was examined several characterizations alignments, such as crystal, surface, functional, elemental composition, retention time, mass spectrum, and elemental oriented properties. Overall, the suggested hybrid system is an eco-friendly pathway for the natural - eradication of contaminants, such as organic and inorganic compounds via waste material (GIO) recycling, modification, oxidation, reduction, adsorption, degradation, and neutralization phenomenon.

A novel core-shell composite of PCN-222@MIPIL for ultrasensitive electrochemical sensing 4-nonylphenol

A novel core-shell composite of PCN-222 and molecularly imprinted poly (ionic liquid) (PCN-222@MIPIL) with high conductivity and selectivity was prepared for electrochemical sensing 4-nonylphenol (4-NP). The electrical conductivities of some MOFs including PCN-222, ZIF-8, NH₂-UIO-66, ZIF-67, and HKUST-1 were explored. The results indicated that PCN-222 had the highest conductivity and was then used as a novel imprinted support. PCN-222@MIPIL with core-shell and porous structure was synthesized using PCN-222 as support and 4-NP as template. The average pore volume of PCN-222@MIPIL was 0.085 m³ g^-1. In addition, the average pore width of PCN-222@MIPIL was from 1.1 to 2.7 nm. The electrochemical response for PCN-222@MIPIL sensor for 4-NP was 2.54, 2.14, and 4.24 times that of non-molecularly imprinted poly (ionic liquid) (PCN-222@NIPIL), PCN-222, and MIPIL sensors, respectively, which result from superior conductivity and imprinted recognition sites of PCN-222@MIPIL. The current response of PCN-222@MIPIL sensor to 4-NP concentration from 1 × 10^-4 to 10 μM presented an excellent linear relationship. The detection limit of 4-NP was 0.03 nM. The synergistic effect between the PCN-222 supporter with high conductivity, specific surface area and shell layer of surface MIPIL results in the outstanding performance of PCN-222@MIPIL. PCN-222@MIPIL sensor was adopted for detecting 4-NP in real samples and presented to be a reliable approach for determining 4-NP.

One-step laser synthesis platinum nanostructured 3D porous graphene: A flexible dual-functional electrochemical biosensor for glucose and pH detection in human perspiration

There has been a recent increase in the demand for wearable sensors for sweat glucose monitoring to facilitate diabetes management in a patient-friendly and non-invasive manner. To address this issue, the key challenge lies in the design of flexible sensors with high conductivity, miniaturized patterning, and environmental friendliness. Herein, we introduce a flexible electrochemical sensing system for glucose and pH detection based on one-step laser-scribed PtNPs nanostructured 3D porous laser-scribed graphene (LSG). The as-prepared nanocomposites can synchronously possess hierarchical porous graphene architectures, whereas PtNPs can significantly enhance their sensitivity and electrocatalytic activity. Benefiting from these advantages, the fabricated Pt-HEC/LSG biosensor exhibited a high sensitivity of 69.64 μA mM^-1 cm^-2 as well as a low limit of detection (LOD) of 0.23 μM at a detection range of 5-3000 μM (covering the glucose range in sweat). Moreover, the pH sensor was functionalized with polyaniline (PANI) on a Pt-HEC/LSG electrode, and it also exhibited high sensitivity (72.4 mV/pH) in the linear range of pH 4-8. The feasibility of the biosensor was confirmed by analyzing human perspiration during physical exercise. This dual-functional electrochemical biosensor displayed excellent performance, including a low detection limit, high selectivity, and great flexibility. These results confirm that the proposed dual-functional flexible electrode and fabrication process are highly promising for application in human sweat-based electrochemical glucose and pH sensors.

Metal Oxides Nanomaterials and Nanocomposite-Based Electrochemical Sensors for Healthcare Applications

Wide-ranging research efforts have been directed to prioritize scientific and technological inventions for healthcare monitoring. In recent years, the effective utilization of functional nanomaterials in various electroanalytical measurements realized a rapid, sensitive, and selective detection and monitoring of a wide range of biomarkers in body fluids. Owing to good biocompatibility, high organic capturing ability, strong electrocatalytic activity, and high robustness, transition metal oxide-derived nanocomposites have led to enhancements in sensing performances. The aim of the present review is to describe key advancements of transition metal oxide nanomaterials and nanocomposites-based electrochemical sensors, along with current challenges and prospects towards the development of a highly durable and reliable detection of biomarkers. Moreover, the preparation of nanomaterials, electrode fabrication, sensing mechanism, electrode-bio interface, and performance of metal oxides nanomaterials and nanocomposite-based sensor platforms will be described.

Three-Dimensional Electrochemical Sensors for Food Safety Applications

Considering the increasing concern for food safety, electrochemical methods for detecting specific ingredients in the food are currently the most efficient method due to their low cost, fast response signal, high sensitivity, and ease of use. The detection efficiency of electrochemical sensors is determined by the electrode materials' electrochemical characteristics. Among them, three-dimensional (3D) electrodes have unique advantages in electronic transfer, adsorption capacity and exposure of active sites for energy storage, novel materials, and electrochemical sensing. Therefore, this review begins by outlining the benefits and drawbacks of 3D electrodes compared to other materials before going into more detail about how 3D materials are synthesized. Next, different types of 3D electrodes are outlined together with common modification techniques for enhancing electrochemical performance. After this, a demonstration of 3D electrochemical sensors for food safety applications, such as detecting components, additives, emerging pollutants, and bacteria in food, was given. Finally, improvement measures and development directions of electrodes with 3D electrochemical sensors are discussed. We think that this review will help with the creation of new 3D electrodes and offer fresh perspectives on how to achieve extremely sensitive electrochemical detection in the area of food safety.

Nanoimmunosensor for the electrochemical detection of oncostatin M receptor and monoclonal autoantibodies in systemic sclerosis

Systemic sclerosis (SSc) is a chronic, autoimmune disease that primarily affects connective tissue. SSc can be classified into limited cutaneous (lSSc) and diffuse cutaneous (dSSc). Oncostatin M receptor (sOSMR) is an important inflammatory biomarker expressed in the serum of patients with autoimmune diseases. A nanoengineered immunosensor surface was developed. The biosensor was composed of a conductive layer of polypyrrole, electrodeposited gold nanoparticles, and sOSMR protein for anti-human OSMR monoclonal antibody biorecognition. The electrochemical response evaluated by cyclic voltammetry and electrochemical impedance spectroscopy indicated the detection of the target analyte present in clinical samples from lSSc and dSSc patients. The voltammetric anodic shift for lSSc specimens was 82.7% ± 0.9-93.6% ± 3.2, and dSSc specimens was 118.7 ± 2.6 to 379.6 ± 2.6, revealing a differential diagnostic character for SSc subtypes. The sensor platform was adapted for identifying sOSMR, using anti-OSMR antibodies as bioreceptors. With a linear response range estimated from 0.005 to 500 pg mL^-1 and a limit of detection of 0.42 pg mL^-1, the sensing strategy demonstrated high sensitivity in identifying the human OSMR protein in clinical samples. The proposed biosensor is a promising and innovative tool for SSc-related biomarker research.

Emerging trends in point-of-care biosensing strategies for molecular architectures and antibodies of SARS-CoV-2

COVID-19, a highly contagious viral infection caused by the occurrence of severe acute respiratory syndrome coronavirus (SARS-CoV-2), has turned out to be a viral pandemic then ravaged many countries worldwide. In the recent years, point-of-care (POC) biosensors combined with state-of-the-art bioreceptors, and transducing systems enabled the development of novel diagnostic tools for rapid and reliable detection of biomarkers associated with SARS-CoV-2. The present review thoroughly summarises and discusses various biosensing strategies developed for probing SARS-CoV-2 molecular architectures (viral genome, S Protein, M protein, E protein, N protein and non-structural proteins) and antibodies as a potential diagnostic tool for COVID-19. This review discusses the various structural components of SARS-CoV-2, their binding regions and the bioreceptors used for recognizing the structural components. The various types of clinical specimens investigated for rapid and POC detection of SARS-CoV-2 is also highlighted. The importance of nanotechnology and artificial intelligence (AI) approaches in improving the biosensor performance for real-time and reagent-free monitoring the biomarkers of SARS-CoV-2 is also summarized. This review also encompasses existing practical challenges and prospects for developing new POC biosensors for clinical monitoring of COVID-19.

Visualization of deformation-induced changes in carbon nanotube networks in rubber composites using lock-in thermography

In this study, we used the lock-in thermography technique (LIT) to successfully visualize the single-walled carbon nanotube (CNT) networks during the tensile deformation of CNT/fluoro-rubber (FKM) composites. The LIT images revealed that the CNT network modes in CNT/FKM during strain-loading and unloading can be classified into four sites: (i) disconnection, (ii) recovery after disconnection, (iii) undestroyable, and (iv) no network. Quantitative analysis of the heat intensity of the LIT also indicated that the change in resistance during strain-loading and unloading plays a role in the balance of disconnection and reconstruction of the conductive network. We demonstrated the ability of LIT to effectively visualize and quantify the network state of the composite under deformation, and the LIT results were found to be strongly correlated with the composite properties. These results highlighted the potential of LIT as a valuable tool for composite characterization and material design.

Conventional and advanced detection techniques of foodborne pathogens: A comprehensive review

Foodborne pathogens are a major public health concern and have a significant economic impact globally. From harvesting to consumption stages, food is generally contaminated by viruses, parasites, and bacteria, which causes foodborne diseases such as hemorrhagic colitis, hemolytic uremic syndrome (HUS), typhoid, acute, gastroenteritis, diarrhea, and thrombotic thrombocytopenic purpura (TTP). Hence, early detection of foodborne pathogenic microbes is essential to ensure a safe food supply and to prevent foodborne diseases. The identification of foodborne pathogens is associated with conventional (e.g., culture-based, biochemical test-based, immunological-based, and nucleic acid-based methods) and advances (e.g., hybridization-based, array-based, spectroscopy-based, and biosensor-based process) techniques. For industrial food applications, detection methods could meet parameters such as accuracy level, efficiency, quickness, specificity, sensitivity, and non-labor intensive. This review provides an overview of conventional and advanced techniques used to detect foodborne pathogens over the years. Therefore, the scientific community, policymakers, and food and agriculture industries can choose an appropriate method for better results.

Advanced growth of 2D MXene for electrochemical sensors

Over the last few years, electroanalysis has made significant advancements, particularly in developing electrochemical sensors. Electrochemical sensors generally include emerging Photoelectrochemical and Electrochemiluminescence sensors, which combine optical techniques and traditional electrochemical bio/non-biosensors. Numerous EC-detecting methods have also been designed for commercial applications to detect biological and non-biological markers for various diseases. Analytical applications have recently focused significantly on one of the novel nanomaterials, the MXene. This material is being extensively investigated for applications in electrochemical sensors due to its unique mechanical, electronic, optical, active functional groups and thermal characteristics. This study extensively discusses the salient features of MXene-based electrochemical sensors, photoelectrochemical sensors, enzyme-based biosensors, immunosensors, aptasensors, electrochemiluminescence sensors, and electrochemical non-biosensors. In addition, their performance in detecting various substances and contaminants is thoroughly discussed. Furthermore, the challenges and prospects the MXene-based electrochemical sensors are elaborated.

Synthesis of a novel carboxybetaine copolymer with different spacer lengths and inhibition of nonspecific protein adsorption on its polymer film

Herein, we designed and synthesized a thermally stable carboxybetaine copolymer with a one- or three-carbon spacer between ammonium and carboxylate groups (CBMA1 and CBMA3) to create an anti-nonspecific adsorption surface with the ability to immobilize antibodies. A series of controlled poly(N,N-dimethylaminoethyl methacrylate) was successfully prepared using reversible addition-fragmentation chain-transfer (RAFT) polymerization and was derived to carboxybetaine copolymers of poly(CBMA1-co-CBMA3) [P(CBMA1/CBMA3)] with various CBMA1 contents, including the homopolymers of CBMA1 and CBMA3. Thermal stability of the carboxybetaine (co)polymers was higher than that of the carboxybetaine polymer with a two-carbon spacer (PCBMA2). Further, we also evaluated nonspecific protein adsorption in fetal bovine serum and antibody immobilization on the substrate coated with P(CBMA1/CBMA3) copolymers using surface plasmon resonance (SPR) analysis. As the CBMA1 content increased, nonspecific protein adsorption on the P(CBMA1/CBMA3) copolymer surface decreased. Similarly, the immobilization amount of the antibody decreased as the CBMA1 content increased. However, the figure of merit (FOM), defined as the ratio of the amount of antibody immobilization to that of nonspecific protein adsorption, depended on the CBMA3 content; FOM was higher when the CBMA3 content was 20-40% than those of CBMA1 and CBMA3 homopolymers. These findings will help enhance the sensitivity of the analysis using molecular interaction measurement devices, such as SPR and quartz crystal microbalance.