Nanowire-Based Electrochemical Biosensors

Photo-induced metal-oxide biosensor for analysis of biofluids

Determining the concentration of biomarkers offers insights into the health condition and performance of the body. The majority of the biosensors applied to measuring biomarkers in biological fluids are electrochemical bases; however, these biosensors suffer from several key drawbacks. These include utilizing complex sensing materials to obtain desirable analytical performance, which prevents their practical application; and operation at a relatively high potential, which leads to inaccurate measurements due to the undesired oxidation of non-target molecules. A novel photo-induced chemiresistive biosensor is introduced here that addresses these challenges. A UV-induced ZnO nanorod (NR) chemiresistive biosensor is developed and applied to monitoring lactate and glucose, as model biomarkers in sweat. The detection mechanism of lactate based on its interaction with ZnO NRs is proposed. Furthermore, the effect of the electrode design and operating parameters, including irradiance, radiation wavelength, and applied potential, are evaluated. The highest response, the shortest response time, and complete recovery are obtained at 5.6 mW/cm2 irradiance of 365 nm and 0.1 V potential. The results indicate that the developed transduction platform utilizing a simple sensing layer is a promising technique with excellent analytical performance for detecting different biomarkers, thereby paving the way toward the emergence of photo-induced chemiresistive biosensors for real-life applications.

Recent Advances in Functional Nanomaterials for Diagnostic and Sensing Using Self-Assembled Monolayers

Functional nanomaterials have attracted attention by producing different structures in any field. These materials have several potential applications, including medicine, electronics, and energy, which provide many unique properties. These nanostructures can be synthesized using various methods, including self-assembly, which can be used for the same applications. This unique nanomaterial is increasingly being used for biological detection due to its unique optical, electrical, and mechanical properties, which provide sensitive and specific sensors for detecting biomolecules such as DNA, RNA, and proteins. This review highlights recent advances in the field and discusses the fabrication and characterization of the corresponding materials, which can be further applied in optical, magnetic, electronic, and sensor fields.

Gelatin-Coated Magnetic Nanowires for High-Sensitivity Optical Labels

The encapsulation of magnetic nickel nanowires (NiNWs) with gelatin is proposed as an alternative for optical label detection. Magnetic nanowires can be detected at very low concentrations using light-scattering methods. This detection capacity could be helpful in applications such as transducers for molecular and biomolecular sensors; however, potential applications require the attachment of specific binding molecules to the nanowire structure. In the present study, a method is presented which is helpful in coating magnetic nanowires with gelatin, a material with the potential to handle specific decoration and functionalization of the nanowires; in the first case, silver nanoparticles (AgNPs) are efficiently used to decorate the nanowires. Furthermore, it is shown that the synthesized gelatin-coated particles have excellent detectability to the level of 140 pg/mL; this level of detection outperforms more complex techniques such as ICP-OES (~3 ng/mL for Ni) and magnetoresistance sensing (~10 ng/mL for magnetic nanoparticles).

A Review on Electrospinning as Versatile Supports for Diverse Nanofibers and Their Applications in Environmental Sensing

Rapid industrialization is accompanied by the deterioration of the natural environment. The deepening crisis associated with the ecological environment has garnered widespread attention toward strengthening environmental monitoring and protection. Environmental sensors are one of the key technologies for environmental monitoring, ultimately enabling environmental protection. In recent decades, micro/nanomaterials have been widely studied and applied in environmental sensing owing to their unique dimensional properties. Electrospinning has been developed and adopted as a facile, quick, and effective technology to produce continuous micro- and nanofiber materials. The technology has advanced rapidly and become one of the hotspots in the field of nanomaterials research. Environmental sensors made from electrospun nanofibers possess many advantages, such as having a porous structure and high specific surface area, which effectively improve their performance in environmental sensing. Furthermore, by introducing functional nanomaterials (carbon nanotubes, metal oxides, conjugated polymers, etc.) into electrospun fibers, synergistic effects between different materials can be utilized to improve the catalytic activity and sensitivity of the sensors. In this review, we aimed to outline the progress of research over the past decade on electrospinning nanofibers with different morphologies and functional characteristics in environmental sensors.

Wearable Sensors for Healthcare: Fabrication to Application

This paper presents a substantial review of the deployment of wearable sensors for healthcare applications. Wearable sensors hold a pivotal position in the microelectronics industry due to their role in monitoring physiological movements and signals. Sensors designed and developed using a wide range of fabrication techniques have been integrated with communication modules for transceiving signals. This paper highlights the entire chronology of wearable sensors in the biomedical sector, starting from their fabrication in a controlled environment to their integration with signal-conditioning circuits for application purposes. It also highlights sensing products that are currently available on the market for a comparative study of their performances. The conjugation of the sensing prototypes with the Internet of Things (IoT) for forming fully functioning sensorized systems is also shown here. Finally, some of the challenges existing within the current wearable systems are shown, along with possible remedies.

Nanomaterial-Based Label-Free Electrochemical Aptasensors for the Detection of Thrombin

Thrombin plays a central role in hemostasis and its imbalances in coagulation can lead to various pathologies. It is of clinical significance to develop a fast and accurate method for the quantitative detection of thrombin. Electrochemical aptasensors have the capability of combining the specific selectivity from aptamers with the extraordinary sensitivity from electrochemical techniques and thus have attracted considerable attention for the trace-level detection of thrombin. Nanomaterials and nanostructures can further enhance the performance of thrombin aptasensors to achieve high sensitivity, selectivity, and antifouling functions. In highlighting these material merits and their impacts on sensor performance, this paper reviews the most recent advances in label-free electrochemical aptasensors for thrombin detection, with an emphasis on nanomaterials and nanostructures utilized in sensor design and fabrication. The performance, advantages, and limitations of those aptasensors are summarized and compared according to their material structures and compositions.

Functional Devices from Bottom-Up Silicon Nanowires: A Review

This paper summarizes some of the essential aspects for the fabrication of functional devices from bottom-up silicon nanowires. In a first part, the different ways of exploiting nanowires in functional devices, from single nanowires to large assemblies of nanowires such as nanonets (two-dimensional arrays of randomly oriented nanowires), are briefly reviewed. Subsequently, the main properties of nanowires are discussed followed by those of nanonets that benefit from the large numbers of nanowires involved. After describing the main techniques used for the growth of nanowires, in the context of functional device fabrication, the different techniques used for nanowire manipulation are largely presented as they constitute one of the first fundamental steps that allows the nanowire positioning necessary to start the integration process. The advantages and disadvantages of each of these manipulation techniques are discussed. Then, the main families of nanowire-based transistors are presented; their most common integration routes and the electrical performance of the resulting devices are also presented and compared in order to highlight the relevance of these different geometries. Because they can be bottlenecks, the key technological elements necessary for the integration of silicon nanowires are detailed: the sintering technique, the importance of surface and interface engineering, and the key role of silicidation for good device performance. Finally the main application areas for these silicon nanowire devices are reviewed.

Nanowire-based sensor electronics for chemical and biological applications

Detection and recognition of chemical and biological species via sensor electronics are important not only for various sensing applications but also for fundamental scientific understanding. In the past two decades, sensor devices using one-dimensional (1D) nanowires have emerged as promising and powerful platforms for electrical detection of chemical species and biologically relevant molecules due to their superior sensing performance, long-term stability, and ultra-low power consumption. This paper presents a comprehensive overview of the recent progress and achievements in 1D nanowire synthesis, working principles of nanowire-based sensors, and the applications of nanowire-based sensor electronics in chemical and biological analytes detection and recognition. In addition, some critical issues that hinder the practical applications of 1D nanowire-based sensor electronics, including device reproducibility and selectivity, stability, and power consumption, will be highlighted. Finally, challenges, perspectives, and opportunities for developing advanced and innovative nanowire-based sensor electronics in chemical and biological applications are featured.

Highly sensitive gas sensing platforms based on field effect Transistor-A review

Highly selective, sensitive and fast gas sensing has attracted increasing attention in the fields of environmental protection, industrial production, personal safety as well as medical diagnostics. Field effect transistor (FET) sensors have been extensively investigated in gas sensing fields due to their small size, high sensitivity, high reliability and low energy consumption. This comprehensive review aims to discuss the recent advances in FET gas sensors based on materials such as carbon nanotubes, silicon carbide, silicon, metal oxides-, graphene-, transition metal dichalcogenides- and 2-dimensional black phosphorus. We first introduce different types of sensor structures and elaborate the gas-sensing mechanisms. Then, we describe the optimizing strategies for sensing performances, response parameters, FET based dual-mode sensors and FET based logic circuit sensors. Moreover, we present the key advances of the above materials in gas sensing performances. Meanwhile, shortcomings of such materials are also discussed and the future development of this field is proposed in this review.

Fabrication of a Sensitive and Stable NiO Uric Acid Biosensor Using Ag Nanowires and Reduced Graphene Oxide

How to detect uric acid is an important issue. For the purpose of preparing a potentiometric uric acid biosensor, this research used nickel oxide (NiO) as the sensing film to deposit it onto the substrate by radio frequency sputtering, then modified it with reduced graphene oxide (rGO) and silver (Ag) nanowires. Reduced graphene oxide (rGO) not only has excellent electrical conductivity, but also can make the surface of the film have a larger surface area, while AgNWs have also been proven to improve catalytic activity; hence, these two materials were chosen as sensor modifiers. Finally, the stability and the various characteristics of the uric acid biosensor were investigated using a voltage–time (V–T) system. The results showed that the AgNW–uricase/rGO/NiO uric acid biosensor has average sensitivity with 4.66 mV/(mg/L). In addition, the sensor has good stability.

PTX-symmetric metasurfaces for sensing applications

In this paper, we introduce an ultra-sensitive optical sensing platform based on the parity-time-reciprocal scaling (PTX)-symmetric non-Hermitian metasurfaces, which leverage exotic singularities, such as the exceptional point (EP) and the coherent perfect absorber-laser (CPAL) point, to significantly enhance the sensitivity and detectability of photonic sensors. We theoretically studied scattering properties and physical limitations of the PTX-symmetric metasurface sensing systems with an asymmetric, unbalanced gain-loss profile. The PTX-symmetric metasurfaces can exhibit similar scattering properties as their PT-symmetric counterparts at singular points, while achieving a higher sensitivity and a larger modulation depth, possible with the reciprocal-scaling factor (i.e., X transformation). Specifically, with the optimal reciprocal-scaling factor or near-zero phase offset, the proposed PTX-symmetric metasurface sensors operating around the EP or CPAL point may achieve an over 100 dB modulation depth, thus paving a promising route toward the detection of small-scale perturbations caused by, for example, molecular, gaseous, and biochemical surface adsorbates.

Effect of nanofiller morphology on the electrical conductivity of polymer nanocomposites

Conductive polymers and nanocomposites have attracted great attention in industry and academia for their tremendous potential applications. Most of the research was focused on the type and amount of nano-additives used and fewer on their morphology which is critical in forming the conductive network. In this paper, a detailed investigation of the effect nanomaterial’s morphology was carried out to study their electrical conductivity properties. Silver nanowire (AgNW) nanocomposite and silver nanoparticle (AgNP) nanocomposite were fabricated. The morphology, crystallinity, and orientation of various silver nanofillers were characterized. AgNW based nanocomposites have shown a lower percolation threshold. A conductive unit based model was established to explain the evolution of the conductive network and aggregation. The aggregation geometry of nanofiller appeared as a dominant factor in altering the percolation behavior.

Electrochemical sensor based on Prussian blue/multi-walled carbon nanotubes functionalized polypyrrole nanowire arrays for hydrogen peroxide and microRNA detection

A dual-sensing platform is proposed based on multi-walled carbon nanotubes/Prussian blue-functionalized polypyrrole nanowire array (PPY/MWCNTs/PB). Highly aligned PPY nanowire arrays were electrochemically prepared on the surface of glassy carbon electrodes, which were doped with MWCNTs/PB nanocomposites. The nanomaterial combines the characteristics of the PPY nanowires (high conductivity and large specific surface area) and MWCNTs/PB (excellent catalytic performance and intrinsic redox activity). Owing to the nanowire microstructure and outstanding electrical properties, the PPY/MWCNTs/PB nanowire arrays show excellent electrocatalysis of the reduction of hydrogen peroxide and facilitate the construction of a high-performance biosensing platform for microRNA (miRNA). A linear relationship between analytical signal and concentration of hydrogen peroxide and miRNA was obtained in the range 5 to 503 µM (1.4-5.1 mM) and 0.1 pM to 1 nM, and detection limits of 1.7 μM and 33.4 fM, respectively. This new supersensitive sensing platform has broad application prospects of biomolecule and other analyte determination in drug, biomedical, plant protection, and environmental analysis. Prussian blue/multi-walled carbon nanotubes functionalized polypyrrole nanowire arrays (PPY/MWCNTs/PB) were prepared by a facile one-step electrochemical method. PPY/MWCNTs/PB nanowire arrays show excellent electrocatalysis of the reduction of H₂O₂ and facilitate the construction of a high-performance biosensing platform for microRNA.

Detection of food spoilage and adulteration by novel nanomaterial-based sensors

Food industry is always looking for more innovative and accurate ways to monitor the food safety and quality control of final products. Current detection techniques of analytes are costly and time-consuming, and occasionally require professional experts and specialized tools. The usage of nanomaterials in sensory systems has eliminated not only these drawbacks but also has advantages such as higher sensitivity and selectivity. This article first presents a general overview of the current studies conducted on the detection of spoilage and adulteration in foods from 2015 to 2020. Then, the sensory properties of nanomaterials including metal and magnetic nanoparticles, carbon nanostructures (nanotubes, graphene and its derivatives, and nanofibers), nanowires, and electrospun nanofibers are presented. The latest investigations and advancements in the application of nanomaterial-based sensors in detecting spoilage (food spoilage pathogens, toxins, pH changes, and gases) and adulterants (food additives, glucose, melamine, and urea) have also been discussed in the following sections. To conclude, these sensors can be applied in the smart packaging of food products to meet the demand of consumers in the new era.

Optimization of GOPS-Based Functionalization Process and Impact of Aptamer Grafting on the Si Nanonet FET Electrical Properties as First Steps towards Thrombin Electrical Detection

Field effect transistors (FETs) based on networks of randomly oriented Si nanowires (Si nanonets or Si NNs) were biomodified using Thrombin Binding Aptamer (TBA-15) probe with the final objective to sense thrombin by electrical detection. In this work, the impact of the biomodification on the electrical properties of the Si NN-FETs was studied. First, the results that were obtained for the optimization of the (3-Glycidyloxypropyl)trimethoxysilane (GOPS)-based biofunctionalization process by using UV radiation are reported. The biofunctionalized devices were analyzed by atomic force microscopy (AFM) and scanning transmission electron microscopy (STEM), proving that TBA-15 probes were properly grafted on the surface of the devices, and by means of epifluorescence microscopy it was possible to demonstrate that the UV-assisted GOPS-based functionalization notably improves the homogeneity of the surface DNA distribution. Later, the electrical characteristics of 80 devices were analyzed before and after the biofunctionalization process, indicating that the results are highly dependent on the experimental protocol. We found that the TBA-15 hybridization capacity with its complementary strand is time dependent and that the transfer characteristics of the Si NN-FETs obtained after the TBA-15 probe grafting are also time dependent. These results help to elucidate and define the experimental precautions that must be taken into account to fabricate reproducible devices.

Non-Carbon 2D Materials-Based Field-Effect Transistor Biosensors: Recent Advances, Challenges, and Future Perspectives

In recent years, field-effect transistors (FETs) have been very promising for biosensor applications due to their high sensitivity, real-time applicability, scalability, and prospect of integrating measurement system on a chip. Non-carbon 2D materials, such as transition metal dichalcogenides (TMDCs), hexagonal boron nitride (h-BN), black phosphorus (BP), and metal oxides, are a group of new materials that have a huge potential in FET biosensor applications. In this work, we review the recent advances and remarkable studies of non-carbon 2D materials, in terms of their structures, preparations, properties and FET biosensor applications. We will also discuss the challenges facing non-carbon 2D materials-FET biosensors and their future perspectives.

Electrochemical biosensors for pathogen detection

Recent advances in electrochemical biosensors for pathogen detection are reviewed. Electrochemical biosensors for pathogen detection are broadly reviewed in terms of transduction elements, biorecognition elements, electrochemical techniques, and biosensor performance. Transduction elements are discussed in terms of electrode material and form factor. Biorecognition elements for pathogen detection, including antibodies, aptamers, and imprinted polymers, are discussed in terms of availability, production, and immobilization approach. Emerging areas of electrochemical biosensor design are reviewed, including electrode modification and transducer integration. Measurement formats for pathogen detection are classified in terms of sample preparation and secondary binding steps. Applications of electrochemical biosensors for the detection of pathogens in food and water safety, medical diagnostics, environmental monitoring, and bio-threat applications are highlighted. Future directions and challenges of electrochemical biosensors for pathogen detection are discussed, including wearable and conformal biosensors, detection of plant pathogens, multiplexed detection, reusable biosensors for process monitoring applications, and low-cost, disposable biosensors.

Multifunctional one-dimensional polymeric nanostructures for drug delivery and biosensor applications

Advances in nanotechnology in the last decades have paved the way for significant achievements in diagnosis and treatment of various diseases. Different types of functional nanostructures have been explored and utilized as tools for addressing the challenges in detection or treatment of diseases. In particular, one-dimensional nanostructures hold great promise in theranostic applications due to their increased surface area-to-volume ratios, which allow better targeting, increased loading capacity and improved sensitivity to biomolecules. Stable polymeric nanostructures that are stimuli-responsive, biocompatible and biodegradable are especially preferred for bioapplications. In this review, different synthesis techniques of polymeric one-dimensional nanostructures are explored and functionalization methods of these nanostructures for specific applications are explained. Biosensing and drug delibiovery applications of these nanostructures are presented in detail.

Highly adjustable 3D nano-architectures and chemistries via assembled 1D biological templates

Porous metal nanofoams have made significant contributions to a diverse set of technologies from separation and filtration to aerospace. Nonetheless, finer control over nano and microscale features must be gained to reach the full potential of these materials in energy storage, catalytic, and sensing applications. As biologics naturally occur and assemble into nano and micro architectures, templating on assembled biological materials enables nanoscale architectural control without the limited chemical scope or specialized equipment inherent to alternative synthetic techniques. Here, we rationally assemble 1D biological templates into scalable, 3D structures to fabricate metal nanofoams with a variety of genetically programmable architectures and material chemistries. We demonstrate that nanofoam architecture can be modulated by manipulating viral assembly, specifically by editing the viral surface coat protein, as well as altering templating density. These architectures were retained over a broad range of compositions including monometallic and bi-metallic combinations of noble and transition metals of copper, nickel, cobalt, and gold. Phosphorous and boron incorporation was also explored. In addition to increasing the surface area over a factor of 50, as compared to the nanofoam's geometric footprint, this process also resulted in a decreased average crystal size and altered phase composition as compared to non-templated controls. Finally, templated hydrogels were deposited on the centimeter scale into an array of substrates as well as free standing foams, demonstrating the scalability and flexibility of this synthetic method towards device integration. As such, we anticipate that this method will provide a platform to better study the synergistic and de-coupled effects between nano-structure and composition for a variety of applications including energy storage, catalysis, and sensing.

Enhanced photoreactivity of amine-functionalized carbon nanotubes under sunlight in the aquatic environment

To overcome the hydrophobic nature of pristine carbonaceous materials such as carbon nanotubes (CNTs) and to make them available for intended applications, chemically covalent functionalization tailoring these materials is widely applied. However, the addition of surface functional moieties often changes the fundamental properties of the parent materials and introduces great variations that hinder a full understanding of and unified conclusions about their environmental implications. In this work, we studied the photoactivity of covalently functionalized CNTs in the aquatic environment under sunlight irradiation. The results indicate an enhanced photoreactivity of CNTs with amine functional groups resulting from a greater excited triplet state formation and a restored electronic structure after the secondary functionalization. Photogenerated singlet oxygen was produced directly through a photosensitization process in which the photoexcited CNTs transferred energy to oxygen, as well as produced indirectly from the aqueous reactions of superoxide radical. The superior photoreactive behaviors of engineered nanomaterials with amine functionalization in terms of reactive oxygen species generation in aquatic environments not only raise ecological concerns, but also render these functionalized engineered nanomaterials useful as water treatment agents against pollutants or microorganisms that can be destroyed by singlet oxygen or hydroxyl radicals.

Electrochemical Biosensors: A Solution to Pollution Detection with Reference to Environmental Contaminants

The increasing environmental pollution with particular reference to emerging contaminants, toxic heavy elements, and other hazardous agents is a serious concern worldwide. Considering this global issue, there is an urgent need to design and develop strategic measuring techniques with higher efficacy and precision to detect a broader spectrum of numerous contaminants. The development of precise instruments can further help in real-time and in-process monitoring of the generation and release of environmental pollutants from different industrial sectors. Moreover, real-time monitoring can also reduce the excessive consumption of several harsh chemicals and reagents with an added advantage of on-site determination of contaminant composition prior to discharge into the environment. With key scientific advances, electrochemical biosensors have gained considerable attention to solve this problem. Electrochemical biosensors can be an excellent fit as an analytical tool for monitoring programs to implement legislation. Herein, we reviewed the current trends in the use of electrochemical biosensors as novel tools to detect various contaminant types including toxic heavy elements. A particular emphasis was given to screen-printed electrodes, nanowire sensors, and paper-based biosensors and their role in the pollution detection processes. Towards the end, the work is wrapped up with concluding remarks and future perspectives. In summary, electrochemical biosensors and related areas such as bioelectronics, and (bio)-nanotechnology seem to be growing areas that will have a marked influence on the development of new bio-sensing strategies in future studies.

Elaborately programmed nanowires fabricated using a tapered push-pull nozzle system

Elaborately programmed silver nanowire arrays can be prepared using a tapered push-pull nozzle system (TPPNS), which is used to directly write micro-nano wires on a substrate via a two-reagent reaction in the diffusion mixing region. The wires could be precisely positioned on the substrate and their width could be freely controlled from the micro to the nano scale, indicating an advance in the methodologies of controlling and fabricating nanowires. The as-prepared silver three-electrode device can serve as a three-electrode sensor.

Bridged oxide nanowire device fabrication using single step metal catalyst free thermal evaporation

In this study, bridge metal-oxide nanowires grown directly between two Si electrodes on SOI wafer and their electrical performance were investigated.

Early detection of Alzheimer's disease using a biosensor based on electrochemically-reduced graphene oxide and gold nanowires for the quantification of serum microRNA-137

Serum miR-137 is quantified for the early detection of Alzheimer's disease using a electrochemically reduced graphene oxide and gold nanowire modified electrode.

Advances in nanowire bioelectronics

Semiconductor nanowires represent powerful building blocks for next generation bioelectronics given their attractive properties, including nanometer-scale footprint comparable to subcellular structures and bio-molecules, configurable in nonstandard device geometries readily interfaced with biological systems, high surface-to-volume ratios, fast signal responses, and minimum consumption of energy. In this review article, we summarize recent progress in the field of nanowire bioelectronics with a focus primarily on silicon nanowire field-effect transistor biosensors. First, the synthesis and assembly of semiconductor nanowires will be described, including the basics of nanowire FETs crucial to their configuration as biosensors. Second, we will introduce and review recent results in nanowire bioelectronics for biomedical applications ranging from label-free sensing of biomolecules, to extracellular and intracellular electrophysiological recording.

Sensitive and Selective Detection of HIV-1 RRE RNA Using Vertical Silicon Nanowire Electrode Array

In this study, HIV-1 Rev response element (RRE) RNA was detected via an Au-coated vertical silicon nanowire electrode array (VSNEA). The VSNEA was fabricated by combining bottom-up and top-down approaches and then immobilized by artificial peptides for the recognition of HIV-1 RRE. Differential pulse voltammetry (DPV) analysis was used to measure the electrochemical response of the peptide-immobilized VSNEA to the concentration and types of HIV-1 RRE RNA. DPV peaks showed linearity to the concentration of RNA with a detection limit down to 1.513 fM. It also showed the clear different peaks to the mutated HIV-1 RRE RNA. The high sensitivity and selectivity of VSNEA for the detection of HIV-1 RRE RNA may be attributed to the high surface-to-volume ratio and total overlap diffusion mode of ions of the one-dimensional nanowire electrodes.

Dynamic scaling of ferromagnetic micro-rod clusters under a weak magnetic field

A controlled configurational change of micro-clusters in suspensions is essential for many smart material applications. In this paper, the dynamic process of ferromagnetic microrod clusters (FMRCs) under an external magnetic field was studied as a function of the cluster size N and the applied field B. The FMRCs rearranged from a side-by-side raft-like structure to an end-to-end chain-like structure, originating from coupled motions through the field-driven alignment of both ferromagnetic microrods and FMRCs. A theoretical model based on an extension of a zig-zag chain was developed, and both the cluster length and orientation could be characterized by a retardation time constant τ, with a relationship τ ∼ N²/B, which agrees well with the experimental results, τ ∼ N^2.2±0.2/B^0.8±0.1. Such a model can be used to predict other cluster dynamics or the magneto-elastic behavior of other soft matters consisting of FMRCs.

Hierarchical core–shell structure of ZnO nanotube/MnO2 nanosheet arrays on a 3D graphene network as a high performance biosensing platform

A hierarchical core–shell structure composed of ZnO nanotubes/MnO₂ nanosheets was fabricated via a two-step electrochemical deposition procedure on the surface of a 3D graphene network (3DGN) as a free-standing monolithic electrode.

Materiomics for Oral Disease Diagnostics and Personal Health Monitoring: Designer Biomaterials for the Next Generation Biomarkers

We live in exciting times for a new generation of biomarkers being enabled by advances in the design and use of biomaterials for medical and clinical applications, from nano- to macro-materials, and protein to tissue. Key challenges arise, however, due to both scientific complexity and compatibility of the interface of biology and engineered materials. The linking of mechanisms across scales by using a materials science approach to provide structure-process-property relations characterizes the emerging field of 'materiomics,' which offers enormous promise to provide the hitherto missing tools for biomaterial development for clinical diagnostics and the next generation biomarker applications towards personal health monitoring. Put in other words, the emerging field of materiomics represents an essentially systematic approach to the investigation of biological material systems, integrating natural functions and processes with traditional materials science perspectives. Here we outline how materiomics provides a game-changing technology platform for disruptive innovation in biomaterial science to enable the design of tailored and functional biomaterials--particularly, the design and screening of DNA aptamers for targeting biomarkers related to oral diseases and oral health monitoring. Rigorous and complementary computational modeling and experimental techniques will provide an efficient means to develop new clinical technologies in silico, greatly accelerating the translation of materiomics-driven oral health diagnostics from concept to practice in the clinic.

Nanowire Chemical/Biological Sensors: Status and a Roadmap for the Future

Chemiresistive sensors are becoming increasingly important as they offer an inexpensive option to conventional analytical instrumentation, they can be readily integrated into electronic devices, and they have low power requirements. Nanowires (NWs) are a major theme in chemosensor development. High surface area, interwire junctions, and restricted conduction pathways give intrinsically high sensitivity and new mechanisms to transduce the binding or action of analytes. This Review details the status of NW chemosensors with selected examples from the literature. We begin by proposing a principle for understanding electrical transport and transduction mechanisms in NW sensors. Next, we offer the reader a review of device performance parameters. Then, we consider the different NW types followed by a summary of NW assembly and different device platform architectures. Subsequently, we discuss NW functionalization strategies. Finally, we propose future developments in NW sensing to address selectivity, sensor drift, sensitivity, response analysis, and emerging applications.

Electrochemical biosensors based on nanofibres for cardiac biomarker detection: A comprehensive review

The vital importance of early and accurate diagnosis of cardiovascular diseases (CVDs) to prevent the irreversible damage or even death of patients has driven the development of biosensor devices for detection and quantification of cardiac biomarkers. Electrochemical biosensors offer rapid sensing, low cost, portability and ease of use. Over the past few years, nanotechnology has contributed to a tremendous improvement in the sensitivity of biosensors. In this review, the authors summarise the state-of-the-art of the application of one particular type of nanostructured material, i.e. nanofibres, for use in electrochemical biosensors for the ultrasensitive detection of cardiac biomarkers. A new way of classifying the nanofibre-based electrochemical biosensors according to the electrical conductance and the type of nanofibres is presented. Some key data from each article reviewed are highlighted, including the mechanism of detection, experimental conditions and the response range of the biosensor. The primary aim of this review is to emphasise the prospects for nanofibres for the future development of biosensors in diagnosis of CVDs as well as considering how to improve their characteristics for application in medicine.